A pollution prevention manual for lithographic printers
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Pollution Prevention Manual for Lithographic Printers
Iowa Waste Reduction Center, University of Northern Iowa
Copyright 1995
Iowa Waste Reduction Center
University of Northern Iowa
Creation of this manual was funded by the U.S. Environmental
Protection Agency, Risk Reduction Engineering Lab under Cooperative
Agreement CR 821492-01-0.
The Pollution Prevention Manual for Lithographic Printers project
team:
Sue Behrns
Kathleen Gordon
Lisa Hurban
Cathy Zeman
The printing project team would like to extend a special thanks to
our advisory committee members:
Dr Ervin A. Dennis, Graphic Communication Program, Department of
Industrial Technology, University of Northern Iowa
Holly Hibbs, Don Griebel, Printing Industries of the Midlands
John Ward, Graphic Arts Technology Center of Iowa
Member of National Association of Printers and Lithographers (NAPL)
Printed on Recycled Paper
Printed with Soy Ink[tm] Trademark of American Soybean Association
Table of Contents
Sections: Page No.
Introduction: 1
1.1 A Perspective on Lithography: 1
1.2 Regulation of Lithographic Wastes: 2
1.3 Practicing Pollution Prevention: 4
Case Study A - Pollution Prevention in a Small Print Shop: 6
2.0 Prepress: 7
2.1 Traditional Imaging: 7
a. Image Processing: 7
b. Developing and Image: 7
c. Fixing an Image: 7
d. Proofing: 7
2.2 Image Carriers: 9
2.3 Pollution Prevention Practices for Image Processing: 9
a. Material Handling and Storage: 9
b. Material Substitution: 10
2.4 Silver Recovery: 11
a. Electrolytic Recovery: 12
b. Metallic Replacement: 13
c. Ion Exchange: 14
d. Silver Recovery from Scrap Film and Paper: 14
2.5 Photographic Chemistry Management: 15
2.6 Wastewater Reduction: 15
2.7 Electronic Technology: 16
Case Study B - Desktop Publishing: 17
2.8 Digital Prepress: 18
a. Direct-to-plate: 18
b. Digital Proofing: 18
c. Soft Proofing: 19
3.0 Printing Inks: 21
a. Ingredients: 21
b. Regulations: 22
3.1 Reducing Waste Ink: 23
Case Study C - Ink Inventory Reduction by In-house Ink Mixing: 25
Case Study D - Ink Recycling to Go: 28
3.2 Soy / Vegetable Oil Inks: 29
Case Study E - Switching From Rubber Based Inks to Soy Based Inks:
29
3.3 Ultraviolet and Electron Beam Curable Inks: 30
Case Study F - The Use of UV Curable Inks: 31
3.4 Waterless Inks: 32
4.0 Dampening System: 33
4.1 Traditional Dampening Systems: 33
4.2 Reducing the Need for Alcohol in Printing: 33
4.3 Pollution Prevention Opportunities for Dampening Systems: 33
a. Eliminating Alcohol from the Dampening System: 34
Case Study G - Selecting Equipment Based on Printing Needs: 34
Case Study H - Selecting Alcohol Substitutes: 39
b. Extending the Useful Life of Fountain Solution: 42
5.0 Press Cleaning: 45
5.1 The Role and Composition of Press Cleaners: 45
5.2 Cleaning Wastes and Alternatives: 45
5.3 Reducing VOC Emissions from Cleaners: 46
a. Equipment to Reduce Cleaning Needs: 46
b. Product Substitution: 47
c. Procedural Changes Reduce Cleaning Wastes: 48
Case Study I - Engineering a Solution: 49
5.4 On-site Cleaner Recycling: 50
6.0 Emerging Technologies: 53
6.1 Waterless Printing: 53
a. Background: 53
b. The Plates: 53
c. Inks and Temperature Systems: 54
d. Conversion Costs: 56
e. Current Uses: 56
f. Benefits: 56
Case Study J - Waterless Printing: 57
6.2 Digital Direct-to-Press: 58
7.0 Recycling in the Graphic Arts Industry: 61
7.1 Potential Recyclables: 61
Case Study K - Recycling at Bankers Systems: 62
7.2 Designing and Maintaining a Recycling Program: 62
7.3 Marketing Recyclables: 63
Case Study L - Comprehensive Recycling Programs: 63
7.4 Obstacles to Recycling: 64
7.5 Pollution Prevention for Lithography: 65
Case Study M - Prethinking Pollution Prevention: 67
1.0 Introduction
This manual is for anyone in the graphic arts industry concerned
with competitiveness, environmental regulations, waste, and
pollution prevention. It is the first product of an on-going
project which begins by addressing wastes from the lithographic
process. Future publications will address pollution prevention for
other areas within the industry. Using this manual and
incorporating its concepts into current waste management practices
could be among the most important business planning decisions made.
Stringent environmental regulations increase demands on the
competitive printer to stay one step ahead of costs related to
environmental compliance. Pollution prevention techniques can help
both small and large printers meet this challenge.
This manual is divided into sections that roughly correspond to the
production stages of the lithographic process. Some sections have
been expanded to highlight pollution prevention approaches in
specific areas such as ink and recycling. Each section provides
specific information on implementation and includes testimonial
examples of pollution prevention measures. These sections can be
used individually to analyze pollution prevention opportunities in
specific areas such as makeready or prepress, or the manual can be
used as a whole to design a comprehensive pollution prevention
program. The first section deals with prepress operations and then
moves on to makeready, inks, dampening, and emerging technologies.
The manual ends with a look at recycling and its contribution to
pollution prevention in the lithographic shop.
1.1 A Perspective on Lithography
The graphic arts industry encompasses Ta wide variety of industrial
endeavors, including "all arts and processes that give information
by means of images printed on surfaces (Dennis & Jenkins, 1991)."
Printing is one such process, differentiated by the process used to
transfer images to the substrate. Direct-to-substrate transfer
processes that use raised or recessed image transfer mechanisms
include flexography, gravure, letterpress and screen printing. The
lithography process uses a blanket cylinder to transfer or "off-
set" images from the plate to the substrate, relying on oil/water
chemistry to maintain an image in one plane on the image transfer
plate. Other related printing sectors include plate-making and
bookbinding (Ramus, 1992).
This manual focuses on lithography, the largest sector of the
graphic arts industry. Based on the value of shipments in 1990
(see Fig. 1-1), lithography accounts for 47 percent of the U.S.
market share (Ramus, 1992). The U.S. printing industry is
comprised of nearly 70,000 facilities -- 60,000 of which operate
both presses and prepress equipment -- and employs 1.5 million
people with an annual payroll of more than $33 billion (Lewis,
1991; Ramus, 1992). Many printing facilities, particularly letter-
press and lithographers, are small businesses with fewer than 10
employees. Fewer than 15 percent of lithography plants employ more
than 20 people (Lewis, 1991). Even so, the U.S. Bureau of the
Census estimated that the total value of all 1991 printing
shipments would exceed $161 billion, making the printing industry
a significant sector of the United States economy (BOC, 1990).
PIE CHART: Fig. 1.1. Percentage of Market Share by Printing Type
47% Lithography
19% Gravure
17% Flexography
11% Letterpress
3% Bindery and Finishing
3% Screen Printing
1.2 Regulation of Lithographic Wastes
The lithographic process can be roughly divided into five steps:
* image processing,
* image transfer to the lithographic plate,
* makeready prior to printing,
* printing,
* drying and finishing of the salable product.
Whether or not all these steps are part of an individual print
shop's operation depends on the degree of computerization and the
type of lithographic press being used-web or sheet-fed. A wide
variety of by-products and wastes are associated with each of these
steps (illustrated in Fig. 1-2) from waste paper and empty ink cans
to less visible wastes such as vapor emissions from inks and
solvents, known as volatile organic compounds (VOCS).
Figure 1.2 Wastes Generated from the Printing Process
* Camera
Film
Wasteswater (Spent fixer/developer)
Silver
* Computer/Plates
Film
Wastewater (Spent fixer/developer)
Silver
* Makeready
Waste ink
White paper
VOCs
Empty ink containers
* Press
Waste ink
Waste paper
VOCs
Empty ink containers
Used plates
Rubber blankets
* Finishing/Bindery
Waste paper trimmings
VOCs
Waste glue
* Wastes from Cleaning Equipment
Waste solvent
Spent cleaning rags
Waste Ink
Empty solvent containers
VOCs
Wastewater
The U.S. Environmental Protection Agency, which compiles the Toxics
Release Inventory database designed to track releases of toxics
from the industrial sector, places graphic arts in the top ten U.S.
industries for amounts of toxic waste released to the air, water,
land and disposed of in hazardous waste management facilities.
Toxins generated from the printing and allied industries exceeded
56 million pounds in 1990 (US EPA, 1992). Other sources report
that the EPA's estimate for the industry may be lower than actual
releases because small business are not normally required to report
releases. Also, some compounds (such as fountain solutions
containing isopropyl alcohol (IPA)), are not reportable (IDEM,
1993).
Volatile organic compounds (xylenes, ketones, alcohols, or
aliphatics) are contained in many of the inks, cleaners and
fountain solutions. The amount of VOCs in inks depends on the
lithographic process and the ink type.
Cleaners (roller, blanket and press washes) are petroleum-based
with products containing naphtha, mineral spirits, methanol and
toluene. Many cleaners contain almost 100 percent VOCS. (Cleaners
that contain highly toxic VOCS, such as methylene chloride are
being phased out.) These compounds readily evaporate at room
temperature and have become a major focus of the Clean Air Act
Amendments of 1990 because they produce ozone in the lower
atmosphere. (Office of Air Quality Planning and Standards, 1993).
VOC emissions account for more than 90 percent of the releases from
printing facilities, as shown in Fig. 1-3 (Pferdehirt, 1993).
BAR CHART: Figure 1.3: Toxic Chemicals Released by Printers
52.7 mil lbs air emissions
1 mil lbs off-site transfers
4700 lbs land releases
1000 lbs land releases
1000 lbs surface water discharges
350 lbs surface water discharges
350 lbs underground well injection
Although this manual is not designed to focus on environmental
regulations affecting the lithographic printer, it will briefly
discuss regulations that affect particular pollution prevention or
waste reduction techniques being described. These regulations
include air emissions, wastewater and hazardous waste requirements.
Compliance with the myriad of ever-changing environmental
regulations that potentially affect the lithographer can be
expensive.
The cost and time required for management oversight, employee
training, documentation, and equipment to pretreat waste discharges
can be considerable. Effective pollution prevention practices and
technologies can help lithographers limit or avoid some of these
expenses. In a highly competitive business environment, pollution
prevention practices can often provide the extra edge that separate
successful printing operations from those beleaguered by excessive
environmental compliance costs and potentially crippling state o
federal regulatory non-compliance penalties.
1.3 Practicing Pollution Prevention
Pollution prevention focuses on eliminating or reducing waste
generation rather than implementing "end of pipe" technology.
The first and most important step in implementing a pollution
prevention (P2) program for any facility is making the philosophy
of waste prevention and reduction a company priority. To achieve
this, a recognized leader at the facility should announce the
program to employees, asking for their input when identifying areas
where waste can be reduced, and to request their help to carry out
pollution prevention projects. Some companies have initiated
bonuses or award programs for employees who contribute
significantly to P2 programs, while others find that employees get
enough satisfaction from involvement in decision-making practices
affecting their production activities to maintain momentum for the
pollution prevention program (US EPA, 1992; DDNR, 1991).
Once a facility establishes a clear commitment to pollution
prevention, it should gather interested, appointed and affected
individuals for a brain-storming session. Participants should
focus on identifying areas in which waste could be reduced based on
e information gained from this manual or others listed in the
reference section. Other important information sources include
records of waste disposal costs, environmental compliance
documents, raw materials purchase invoices or a informal inspection
of dumpster con tents. Press operators and bindery personnel can
often accurately identify processes or procedures that generate
high volumes of waste and emission.
After high waste areas have been identified, focus on one for the
facility's first pollution prevention effort. Concentrate on
identifying the most favorable pollution prevention methods for
eliminating or reducing that waste stream. This requires
consideration of all costs and benefits involved, such as decreases
in operating costs, regulatory compliance costs, the likelihood of
regulatory violation costs and future regulatory liability (see
Fig. 1-4). Improvements in productivity, worker safety,
environmental protection and in quality management practices may
also result (SHWEC, 1993). For example, a material substitution
approach may be chosen to replace a rubber-based ink with a
soy/vegetable oil-based ink, or an IPA-containing fountain solution
with butyl cellosolve or 2-ethyl-1, 3-hexanediol-based substitute
Fig. 1-5.
Figure 1.4. Basic Approaches to Pollution Prevention
Changes in Production Processes
* material substitution
* purification of materials
* equipment modifications
* equipment automation
* waste segregation
* inventory control
* good material handling practices
Changes in Manufactured Product
* product redesign for less environmental impact
* design for longer life
* pre-design considerations for less environmental impact
Figure 1.5. Potential Benefits of Pollution Prevention Practices
Decreased waste management costs:
Means: Bottom line savings
Decreased environmental compliance costs:
Means: Less time spent assuring compliance
Decreased future environmental liability:
Means: Decreased likelihood of site clean-up
Increased future property values
Increased efficiency and productivity:
Means: On-time delivery and quality work
Increased worker safety:
Means: Decreased workers compensation claims, sick time
Increased productivity
Regardless of the approach taken, establish a means for measuring
the impact of the pollution prevention project (US EPA, 1988).
First examine and quantify the costs associated with previous
production methods to the greatest extent possible. Then compare
this to the costs (including any equipment purchases necessary) to
implement the P2 project. Any net savings should be divided by the
cost of new equipment, supplies and labor to determine the return
on investment.
While these are important tools for the evaluation and guidance of
P2 project decisions, intangible benefits and costs should also be
considered. Of what value is an improved business image or a
healthier work environment? Intangibles often translate into real
costs or real savings and should not be treated lightly (US EPA,
1992).
Keeping a viable pollution prevention program going requires
continued support and involvement from management and constant
effort from everyone involved in planning and implementation.
Obstacles may include concerns about product quality, resistance to
change on the part of management or staff or prohibitive state or
federal regulations. However, with continued support and
enthusiasm from respected persons within the company, the
lithographer can implement sound pollution prevention projects.
Pollution prevention can become part of quality management
practices contributing to the company's bottom line and to
environmental quality.
Case Study A: Pollution Prevention in a Small Print Shop
Dan Crotty, production manager at G&R Publishing Company, in
Waverly, Iowa, tries to keep on top of new developments in
pollution prevention for small business printers and implement as
much as possible at G&R.
In addition to recovering waste silver and spent photographic films
from its prepress operations, using automatic dampening systems on
its presses to reduce makeready waste, and baling and recycling
corrugated cardboard waste, G&R employs several approaches to
reduce the amount and toxicity of waste from its press room.
Currently, G&R uses soy inks whenever possible, except for metallic
inks, for which suitable soy replacements are not available.
Crotty found that switching to soy ink was not extremely difficult
and credits this to two things. First, he and his press operators
take the time to work with the slower-setting soy ink to avoid set-
off problems. Second, at the time of the switchover, G&R began
using a computer-controlled mixing program for PMS and specialty
colors. To maximize benefits, Crotty decided to order inks without
dryers so he could customize the drying characteristics of his inks
and prevent skinning for partially-used inks in storage.
When Crotty and his press operators mix PMS and specialty inks,
they can custom formulate the drying time for optimal press
performance. Crotty is pleased with the amount of inventory
reduction achieved with computer-controlled mixing, estimating that
excess PMS color stock has decreased by about 40 percent since
installing the system.
Crotty cautions that accurate measuring and using inks that do not
have dryers already added are necessary to make in-house mixing
effective.
In addition to focusing P2 efforts on inks, G&R has reduced
volatile organic compound emissions from fountain solutions by
replacing isopropyl alcohol with substitutes. It also employs
chiller units with filters to keep solutions cool, clean and to
avoid evaporation.
When G&R press operators switched to alcohol substitutes, they
discovered they needed a water supply with low conductivity. They
installed a reverse osmosis unit to eliminate metal salts in make-
up water, which, according to Crotty, was immensely helpful in
allowing the press operators to run IPA-free without scumming
problems. Crotty also makes sure that his alcohol-free Heidelberg
MOZ-P has quality rollers in place to guarantee that the technique
is successful.
When Crotty started at G&R 14 years ago, he began to search for
ways to save, money in the press room and helped establish
pollution prevention as part of the "cultural ethic" at G&R. By
closely following industry publications and researching vendor
information, Crotty continually watches for developments in
pollution prevention that might benefit G&R's operations.
His advice to other lithographers considering implementing
pollution prevention practices: "The less waste you create, the
less you throw away, and the more money you save." But, he
cautions, "Don't wait until the last minute to implement pollution
prevention measures," because you may well be at a competitive
disadvantage to other printers who have made changes early on.
2.0 Prepress
Traditionally, images have been made with a camera using film that
is exposed and then developed. A printing plate is then made from
the photographic negative or positive and that plate acts as the
image carrier to the intermediate (blanket) where the image is
finally transferred to a substrate.
2.1 Traditional Imaging
Prepress can be divided into two steps: image processing and image
transfer.
Image processing is the preparation of art or copy, typesetting,
and photoprocessing. Image transfer is the preparation of a plate
from a photographic negative or positive. The primary wastes
during image processing and image transfer are processing
chemicals, silver and wastewater.
Many of the procedures used to prepare and transfer an image are
similar, so waste reduction options for image processing and image
transfer will be presented together. Although photoprocessing and
plate processing steps are similar, their individual waste streams
(chemistries) should not be combined. Segregating waste will allow
more effective reuse and recycling.
a. Image Processing
The printing industry uses photography to reproduce both art and
copy, employing materials similar to those in other fields of
photography. These materials include film, which has a paper,
plastic or glass base covered with a light-sensitive coating (the
photographic emulsion). This emulsion is usually composed of
silver halide salts in gelatin. Silver halide salts include silver
chloride, silver bromide and silver iodide. Most photographic film
bases are polyester.
b. Developing an Image
An image is photographed and processed to produce a photographic
positive or negative. Films or plate developing solutions are
alkaline and typically contain benzene derivatives like
hydroquinone, pyrogallol, catechol, p-phenylene diamine, p-
aminophenol, metol, amidol and pyramidal. The most common
developing agents are hydroquinone and metol. In general,
developing solutions also contain an accelerator, which increases
the activity of the developer; a preservative, which reduces
oxidation damage to the developer; and a restrainer, which inhibits
the formation of "fog" on the image. Developing solutions should
be in trays only slightly larger than the materials being processed
and solution temperatures should be maintained within 1/4 deg. F of
product guidelines (Jacobs Engineering Group Inc., 1988).
c. Fixing an Image
Developing action is stopped by immersing film into a fix bath of
sodium thiosulfate (hypo), ammonium thiosulfate or sodium
hyposulfite. These chemicals convert metallic silver to soluble
complexes. Hypo, the major ingredient of fixing baths, also
contains potassium alum, acetic acid and sodium sulfate. Acetic
acid is used to keep pH low, which neutralizes the alkalinity of
developing solutions and to stop the developing action.
Fresh fixing bath typically has a pH of 4.1, which is slightly
acidic (Hartsuch, 1983). Alkaline developer is carried over into
the fixer bath on films and prints, which raises the pH slightly.
When the pH reaches 5.5, the fogging preventative becomes less
effective, requiring the operator to change the fix bath or lower
the pH by adding more acetic acid. An acidic stop bath is often
used prior to the fixer to stop the action of the developing
solutions and prevent fix bath contamination.
After the negative or positive is fixed, some of the fix bath
chemicals (hypo) remain in the gelatin emulsion layer. Chemicals
remaining in the emulsion can react with the silver to form yellow-
brown silver sulfide. To prevent this, fix chemicals are washed
from the emulsion in a water bath until the hypo is dissolved. For
optimum hypo removal, water pH should be above 4.9 (USEPA, 1990).
Chemicals are used to change image contrast by reducing or
increasing the metallic deposits on the film. Reducers oxidize
some of the metallic silver in the emulsion to soluble salt, and
intensifiers increase silver deposit blackness by adding silver or
mercury to the developed silver grains in the emulsion. Small
amounts of chemicals and silver rinsed from film can accumulate in
the final water bath.
The photographic industry is the largest user of silver in the
United States (49 percent) with an estimated 1985 usage of 58
million troy ounces (Cooley, 1988). In addition, American printers
generated an estimated 40 million gallons of waste working-strength
developer and 30 million gallons of fixer each year (Knapp, 1993).
This reveals a need and opportunity for P2 in prepress operations.
Non-hazardous wastes generated during image processing include
empty containers, used film packages, film spools and outdated
materials. Recycling opportunities are presented in greater detail
in section 7.
The primary components of the prepress waste stream are used film,
silver dissolved from processing film and wastewater containing
photographic chemicals. Photographic chemicals may have
significant biological oxygen demand (BOD) that can interfere with
the effectiveness of the receiving wastewater treatment facility.
Local, state and federal requirements must be met prior to
discharging silver-bearing solution to a wastewater treatment
system.
A small amount of silver enters the fix bath solution each time
film or paper is immersed. Insoluble compounds form after silver
concentrations reach a certain level and cannot be removed from the
photographic emulsion. Fix baths should be recycled before this
point is reached. The critical silver concentration for fix baths
is 0.27 ounces per gallon (2 grams/liter). Adding ammonium
thiosulfate to a bath doubles the maximum allowable silver
concentrations (Jacobs Engineering Group Inc., 1988).
d. Proofing
After the image processing step, a proof is produced to show
whether the color is correct and how the job will look when
printed. The two most common proofs are press proofs and off-press
proofs such as blue lines, color keys and chromo checks. Press
proofs are more expensive, require a press and printing plates and
generate more waste. Off-press proofs are produced directly
(usually photographically) and serve as a quality control check of
camera, scanner separations and corrections. Electronic imaging
makes it possible to reduce excess waste from post-film proofing.
Wastes associated with press proofs are film, paper and developing
chemistries.
The printing process revolves around the intermediate image carrier
-- a plate -- that accepts ink from a roller and transfers it to a
rubber blanket. There are several types of surface plates used in
offset lithographic printing: presensitized laser imaged,
electrostatic, diffusion transfer, photo direct and direct imaged
plates.
Wastes associated with image carriers include damaged plates,
developed film, acids, alkalis, solvents, plate coatings (dyes,
photopolymers, binders, resins, pigment, organic acids), plate
developers (isopropanol, gum arabic, lacquers, caustics), dated
materials and rinse water.
Developing and finishing presensitized lithographic plates
generates small volumes of wastewater. Therefore, the primary P2
effort when using presensitized plates is to reduce photographic
chemistry consumption and to recycle the used plate.
2.3 Pollution Prevention Practices for Image Processing
The primary pollution prevention options for image processing are:
* material handling and storage
* material substitutions
* silver recovery
* photographic chemistry management
* wastewater reduction
* electronic technology
* digital prepress
a. Material Handling and Storage
* Chemicals sensitive to temperature and light should be stored
according to manufacturers' directions.
* Storage areas should be free of dust or other contaminants that
could destroy raw materials.
* Implement first-in/first-out inventory practices; watch
expiration dates closely.
* Perform small scale tests of outdated materials prior to disposal
(expiration dates are estimates.)
* Avoid overstock--order raw materials according to usage demands.
* Inspect new materials carefully, return damaged or near
expiration supplies.
* Whenever feasible, purchase often used or high demand raw
materials in bulk. Returnable or refillable totes are available
from many vendors.
Improper storage and handling of raw materials can cause spoilage
and increased inventories of out-dated or expired material. Many
photoprocessing and plate developing chemicals are light and
temperature sensitive. Chemical container labels list recommended
storage conditions and shelf life that should be followed
explicitly. Keep inventories using first-in, first-out practices,
which will help reduce expired shelf life. Computerized inventory
systems are available to track the amounts and ages of in-stock raw
materials and may facilitate purchasing decisions. Purchase
specialty or rarely used materials in quantities that will allow
complete use prior to expiration whenever possible. Expiration
dates are estimates and many factors affect their accuracy, so test
expired products for effectiveness before disposal.
Large volume printers should purchase raw materials in bulk and
make arrangements with their vendors to recycle the containers or
return them in exchange for full containers of new product.
Inspect all materials upon arrival--unacceptable or damaged product
should be returned to the manufacturer or supplier. In addition,
inspect materials prior to use to avoid using an unacceptable
product.
b. Material Substitution
* Use dry positive proofs or aqueous developed proofs.
* Ask vendors for non-hazardous chemical substitutes to replace
intensifiers and reducers that contain mercury or cyanide salts.
* Accept only non-hazardous product samples.
* Use silverless films such as diazo, vesicular, photopolymer,
electrostatic or selenium-based.
* Use pre-sensitized lithographic plates.
* Discontinue using etched plates.
* Use water-developed plates.
* Ask vendors for non-hazardous developers and finishers.
Non-hazardous proofs such as dry positive proofs that use
ultraviolet (UV) light to develop, or aqueous proofs that require
only water for development can be substituted for hazardous ones.
Vendors are excellent sources of information about substitutes for
new or less toxic chemicals. Ask them to provide information about
hazardous chemicals on a continuing basis. Use caution when
accepting samples; be sure that the product does not contain
hazardous components that require costly disposal.
Most spent films will pass the Toxicity Characteristic Leaching
Procedure (TCLP) tests and not be a hazardous waste. (See Appendix
A) However, photographic films are available that do not contain
silver, and their development produces non-hazardous fixer wastes.
In the past, these films have been slower speed than silver halide
films, but film advances allow silverless films to compete
favorably in both quality and speed. Diazo and vesicular films
have been used for many years as silverless substitutes, but
recently photopolymer and electrostatic films are more commonly
used. Vesicular films have a honeycomb-like cross section and are
constructed of a polyester base coated with a resin and light-
sensitive diazonium salt. Photopolymer films contain carbon black
as a substitute for silver. These films are processed in a weak
alkaline solution, which is nonhazardous when the pH is adjusted to
meet sanitary sewer discharge limits prior to disposal.
Electrostatic films are non- silver films with speeds and
resolutions almost identical to silver-based films. An
electrostatic charge makes them light sensitive.
A new dry process film is being tested that contains selenium
encapsulated in the polymer layer, where it remains throughout the
life of the film. A combination of charging, exposure to light and
heat development during the imaging process causes the selenium
molecules to migrate deeper into the polymer layer, resulting in a
visible image. Because selenium is a regulated toxic metal, film
disposal could pose problems in some parts of the United States if
a recycling program for selenium is not implemented by the film's
manufacturer.
Again, ask photographic vendors for non-hazardous or less hazardous
substitutes. Many commonly used photographic intensifiers and
reducers contain hazardous compounds like mercury or cyanide salts.
Non-hazardous developers and finishers are available that are
reported to be non-toxic and have a flash point over 2000 deg F.
Presensitized lithographic plates are an excellent alternative to
metal etched plates. Some presensitized plates are processed with
water only, further eliminating wastes. Plates can also be
produced directly from copy or artwork, eliminating the need for
photoprocessing.
2.1 Silver Recovery
* Install electrolytic deposition for silver recovery from fix
solutions.
* Install metallic replacement canisters to recover silver.
* For large volumes of wastewater, install an ion exchange unit.
* Use an automated recirculating silver recovery, water recovery
and chemical replenishment system.
* Recycle spent film and negatives when feasible.
Silver can be removed from fixer and bleach-fix. As much as 80
percent of the total silver processed for black and white positive
and almost 100 percent of the silver in processed color work will
end up in the fixer or bleach-fix solution. Silver is also present
in rinse water following the fix because of carryover. Some
facilities use a primary silver recovery unit, which removes the
bulk of silver, in combination with a "tailing" unit to treat the
relatively low silver concentration effluent from a primary
recovery system.
Color developer effluent is not processed through a silver recovery
system. Silver content of color developer is very low while its pH
is high. If mixed with other silver bearing solutions, it reduces
the efficiency of silver recovery and results in ammonia
generation. Recovered silver can be sold for as much as 80 percent
of its current market value. Desilvered fixer and developer can be
reused once the silver has been removed and the correct chemical
balance has been restored.
Photoprocessors commonly use three silver recovery methods. The
first two, electrolytic (electrowinning) and metallic replacement
are used to recover silver from spent fix solutions. The third
method, ion exchange, is used to remove silver from rinse water.
Ozone oxidation, reverse osmosis and chemical precipitation are
less frequently used methods to recover silver.
a. Electrolytic Recovery
Electrolytic silver recovery is the process of passing silver-
bearing solution between two electrodes. In an electrolytic
recovery unit, a low voltage direct current is created between a
carbon anode and a stainless steel cathode. Metallic silver plates
onto the cathode. Once the silver is removed, the fixing bath may
be reused by mixing the desilvered solutions with fresh fixer.
Factors that can affect the operation and efficiency of
electrolytic silver recovery unit are:
Silver concentration--Recovery efficiency is directly related to
the silver concentration of the fixer. The higher the silver
concentration, the higher the plating efficiency. When silver
concentration is below 1 gram/liter (0.12 troy oz./gal), plating
efficiency and plating current decrease rapidly, reducing the
recovery rate.
Type of fixer--The type of fixer can greatly affect the
electrolytic recovery process and the type of electrolytic cell
required. For example, bleach-fix solutions require specially
designed equipment. Special "electro" fixers are available with
increased concentrations of sulfite. A sufficient amount of sodium
sulfite must be present in the fixer for the electrolytic process
to work properly because sodium sulfite is consumed during plating.
Line voltage--Another factor that can reduce plating efficiency is
line voltage; low voltage will cause reduced plating. High voltage
causes improper equipment operation. Optimal line voltage depends
on the concentration of silver in the fix solution.
pH--The fixer's pH has a direct relationship on plating efficiency
of the recovery cell. With conventional X-ray and graphic arts
fixer, a pH of 4.5 to 5.5 is ideal. At a pH above 5.5, recovery
efficiency decreases drastically. Specially coated paper kits are
available from photo chemistry vendors to estimate the fixer's
silver concentration, sulfite concentration and pH. These
inexpensive aids help maximize silver recovery efficiency.
Fixer solution desilvered by electrolytic recovery methods still
contains higher than allowable levels of silver for discharge to
the sewer. Acceptable levels of silver in wastewater vary widely,
so contact a local wastewater treatment professional for
information concerning the levels of silver allowable for discharge
in your area. Using a follow-up recovery method or tailing method
such as a metallic exchange canister to reduce silver to allowable
levels is advised. Electrolytic recovery can be used as a batch
recovery system, a continuous recovery system or as a recirculating
recovery system. In batch recovery, overflow fixer is collected in
a tank and stored. When a sufficient volume has accumulated, the
waste fixer is pumped to an electrolytic cell for silver removal.
The desilvered fixer can be discharged to the sewer (depending on
remaining silver concentration), or reused. If reused, sodium
thiosulfate is added to replenish its strength. Batch system cells
are usually designed to desilver the fixing bath to silver
concentrations of about 5,000 mg/l. The effluent typically
contains 200-500 mg/l of silver. Tailing units (metallic exchange
canisters) are required to further polish the effluent and reduce
silver concentration to sewerable levels.
Recovery units operated on a continuous recovery program must be
carefully sized to allow the fixer sufficient residence time for
optimal silver plating. Some units can sense silver concentrations
and will automatically adjust current densities.
Batch treated waste must be included in the monthly hazardous waste
generation rate. Waste from both continuous and recirculating
units does not need to be included because it is not stored.
Recirculating electrolytic silver recovery systems are installed
in-line to remove silver at approximately the same rate that it is
added by film processing. A continuous stream of fixer from in-use
process tanks is circulated through the unit, silver is removed and
the fix is returned to the process tank for reuse. Each
photoprocesser requires a separate unit. Different types of
electrolytic recovery systems are available for treating all types
of non-bleach fix bath equipped with circulation pumps. Fix
chemistry requires monitoring and replenishment as needed.
In all applications of electrolytic silver recovery, be sure to
control the current density so that "sulfiding" does not occur.
Sulfiding is the decomposition of thiosulfate into sulfide at the
cathode. This contaminates the deposited silver and reduces
recovery efficiencies. Remember this rule of thumb: the higher the
silver concentration, the higher the current density can be without
sulfiding. Therefore, as silver is plated out of solution, the
current density must be reduced.
b. Metallic Replacement
The metallic replacement method for silver recovery is based on the
principle that a more active metal (iron, zinc or aluminum) will
replace a less active metal (silver) in solution. Spent fixing
bath passes through a canister or bucket containing steel wool or
a mesh screen. The silver settles to the bottom of the canister as
a sludge. The silver-bearing sludge needs to be refined further;
therefore, its resale value is considerably lower.
The amount of silver that a recovery system should yield can be
calculated by multiplying the silver concentration of the solutions
entering the recovery cartridge by the volume of solution being
treated. For example: If the average concentration of silver in
the solution is 1/2 troy ounce per gallon (as measured using a test
strip) and 400 gallons are treated, the potential recovery is 200
troy ounces of silver.
Specially designed silver-estimating test papers impregnated with
a chemical substance that changes colors according to the amount of
silver present in a solution are used to determine a solution's
silver concentration. These test papers should also be used to
determine the silver content of effluent from the final cartridge.
To test for silver levels of less than I gram/liter, soak the test
papers in the solution being tested for one hour before comparing
to the color indicator.
If a canister fails to collect silver or the silver yield does not
meet expectations, any of the following may be the cause:
* Type of film being processed
* Exposure level
* Processing work load
* Replenishment rate
* Solution carry-out
* Obstruction of solution flow
* Channeling
* Flow rate
* Incorrect type of recovery cartridge
* Incorrect installation
* Chemical condition of the fixing solution
* pH of the fixer
A series of canisters is recommended to recover silver. When
canisters are used in a series the first canister removes the bulk
of the silver, and the second polishes the effluent of the first
and also serves as a safety factor if the first unit is overloaded.
When the first canister is exhausted, the second becomes the first,
and a fresh unit replaces the second. Change-out is recommended
when the silver in the effluent of the first cartridge reaches 25
percent of the influent concentration. For most effective
operation, the pH of solutions passing through the metallic
replacement canister should be between 5 and 5.5. Below 4, the
steel wool dissolves too rapidly; above 6.5, the replacement
reaction is so slow that silver removal is incomplete. Proper pH
control is critical for high silver recovery (KODAK, 1986).
A series of metallic replacement canisters can recover
approximately 85 percent of the recoverable silver in the form of
sludge. Fixer that is desilvered using a metallic replacement
bucket can not be reused as fix chemistry because of the excessive
iron concentration in the effluent (-4,000 mg/1). Metallic
replacement buckets may remove silver to levels acceptable for
discharge to the sanitary sewer (KODAK, 1986).
e. Ion Exchange
Ion exchange is the reversible exchange of ions between a solid
resin and a liquid. The silver-thiosulfate complex has a high
affinity for the resin, making silver reclamation and resin
regeneration difficult. Resin plugging -by suspended matter such
as gelatin has been a problem. Ion exchange recovery is used to
polish silver-bearing rinse water and can produce effluent with
silver concentrations as low as 0.1 ppm, recovering as much as 98
percent of the silver. Typically, ion exchange is used with large
volumes of rinse water.
d. Silver Recovery from Scrap Film and Paper
Scrap film and paper contain silver salts or elemental silver.
Silver recovery services may agree to recycle scrap film and paper
with the silver recovered from spent fix. Another option is the
removal of silver from unprocessed scrap film and paper by treating
the material with sodium hypochlorite solution to oxidize elemental
silver to a silver salt. Once dissolved in the fixer, silver can
be recovered using any of the methods previously discussed.
Because scrap film can be messy, processed or unprocessed film can
be soaked in an agitated hot sodium hydroxide solution to remove
the emulsion. Silver can be separated from this solution by
settling, centrifuging or filtering.
2.5 Photographic Chemistry Management
* To extend bath life, add ammonium thiosulfate (consult the
chemical manufacturer first).
* Add acetic acid to fix bath.
* Use an acid stop bath prior to fixing.
* Closely monitor chemical replenishment.
* Keep chemical containers closed.
* Add marbles to bring the level of partially used chemicals up to
the top to lessen chemical oxidation.
* Install floating lids.
* Use squeegees during hand development or install them on
automatic processors.
* Reuse color developer, adjust as needed.
* Reuse desilvered fixer, replenish as required.
Process bath life can be extended by adding ammonium thiosulfate,
which doubles the allowable concentration of silver buildup in the
bath, using an acid stop bath prior to the fix bath and adding
acetic acid to the fixing bath to keep the pH low. Contact the
chemical vendor and/or manufacturer for product information and
suggested methods to extend the bath life.
Using squeegees to wipe excess liquid in a non-automated processing
system can reduce chemical contamination in carryover from one
process bath to the next by 50 percent (TIP). Minimizing
contamination increases recyclability, extends the life of process
baths and reduces the quantity of replenisher chemicals required to
complete processing. Be cautious when using squeegees; film may be
damaged if the image has not hardened completely.
Floating lids can reduce contamination and evaporative losses in
bleach and developer tanks. Small scale developers can use glass
marbles to raise the liquid level of process chemicals to the brim
of the container each time the fluid is used. This procedure
extends chemical life by reducing the amount of oxygen to which the
liquid is exposed.
2.6 Wastewater Reduction
* Employ countercurrent rinsing techniques.
* Recirculate rinse water.
* Use automatic flow controls for rinse water.
* Use rinse bath agitators.
Compared to traditional parallel tank wash systems, counter current
washing reduces the amount of contamination in processing solutions
and conserves water. Rinse water is used in the initial film wash
and fresh water is introduced only at the final rinse stage, where
most of the contamination has been removed by earlier stage
rinsing.
Automatic rinse water flow controls can be installed in place of
continuous flow systems that constantly consume water whether film
is being processed or not. Set automatic water flow controls to
ensure a complete water change-out in the tray once every five
minutes. The method by which the water enters and leaves the
washing tank also affects the efficiency of the washing process.
Best results are achieved when water enters at the bottom of the
tray and leaves at the top. Moderately warm wash water (80 deg. F)
helps remove the hypo. Automatic water and temperature flow
controls, when used in conjunction with mechanical agitation, can
decrease hypo removal time by 30 percent (USEPA, 1990).
2.7 Electronic Technology
Recently, prepress has undergone tremendous technological change
with the explosion of electronic capabilities and computer chip
technology. The goal of electronic prepress is to create a
completely digital master copy by using computer systems that
electronically combine type, drawings and images. Electronic
prepress and imaging may involve preparing text using a personal
computer to create disk files, create page layout, graphics and for
typesetting. Editing is immediate and design elements are easily
manipulated by composition software programs.
Scanners can be used to scan images and send them directly to make
plates. and images can now be created electronically with digital
cameras. These cameras capture an image, digitize it and either
store the image for input at a later time or immediately transport
the image to a computer for editing or enhancement.
The obvious advantages of electronic prepress are speed, reduced
prepress costs associated with traditional methods, labor savings,
editing time and ease, the ability to integrate a number of files
on disk and unlimited creative options.
Another major benefit of electronic prepress is the opportunity to
reduce or prevent pollution (silver-bearing wastes) typically
generated using traditional methods.
Digital prepress also has some disadvantages, including the high
initial cost (approx. $30,000 and up) of acquiring the necessary
computer hardware and software, scanners and expansion or add-on
technologies such as digital cameras. Technicians may also require
training.
Many printers find that a combination of traditional and desktop
publishing works well and is cost-effective. Emerging technologies
and trends in electronic publishing will be covered in Section 6.0.
PHOTO: Man at Computer [refer to source document]
Case Study B: Desktop Publishing
Rapid Printing, Des Moines, Iowa, responding to increases in
chemical and disposal costs, moved away from traditional
typesetting and printing to desktop publishing.
Initially, Rapid Printing purchased a Macintosh and a printer.
Kevin Brown, owner, tried to run a hybrid system with one desktop
publishing system and four traditional Compugraphic typesetters.
The desktop publishing system sat in the box until Brown contacted
a consultant to install the software and train his staff. Once the
staff became familiar with the Macintosh, it became the system of
choice, which made integrating both systems difficult.
The time had come to make a choice: desktop or traditional.
"There really was no choice, my employees loved desktop publishing
because it worked great, it saved time, and my old typesetters were
about worn out.... one Mac simply could not do the work of four
typesetters," Brown commented.
Brown secured a $23,000 loan to purchase three more Macs, a second
laser printer, and replaced the original Macintosh with a newer,
large screen model. With these purchases he had desktop publishing
stations capable of matching the demand. The changeover allowed
Rapid Printing to expand its font library from 80 to 400. Graphics
capability increased dramatically. The software selected included
page design, drawing and image manipulation programs.
Again, the consultant set up t desktop publishing system and
trained employees.
The transition was "just painful! Going cold turkey for the first
three weeks was a nightmare," said Brown. There were the
inevitable bugs to be worked out of the programs, they had trouble
downloading fonts correctly so that the computer would read them.
Additional sub-programming was needed to hold the large number of
fonts now available. They even experienced a total shutdown of the
system until the problems were ironed out. The consultant walked
them through every step of the process, training the employees how
to troubleshoot and solve problems, not just which keys to hit to
fix something.
Brown's advice to printers who are contemplating desktop
publishing: "Find a good consultant, shop around, do not overlook
universities, colleges or community colleges." They have job
placement offices and internship programs that provide programmers
at a reasonable cost. Established consulting firms also provide
assistance but at a much higher cost. "Shop around before you make
a decision, but hire the best consultant you can afford."
Brown and his employees have set the stage for future activities
focusing on P2 and emerging technologies. Currently, Brown is
seeking additional capital to purchase four more computers to and
update his current desktop capabilities. Ultimately, Brown plans
to technologies such as direct-to-plate to eliminate traditional
photoprocessing and plate making and the hazard wastes that are
typical of these traditional methods.
2.8 Digital Prepress
Digital technologies eliminate pre-press waste even further than
desktop publishing by directly transferring a computer-generated
image to the plate.
Although there are many different types of digital technologies,
this manual only addresses direct-to-plate, direct-to-press, and
digital proofing from the waste reduction aspect. Direct-to-press
is addressed in Section 6.2
a. Direct-to-plate
Direct-to-plate technologies enable a printer to image a computer-
generated design directly to the plate. Digital plate quality
exceeds film-based because there is no image degradation from film
contact with the plate.
Other advantages of direct-to-plate technologies are:
* Reduced labor costs from stripping and platemaking as customers
supply jobs on computer disks.
* Reduced material costs by eliminating film and processing.
* Significantly reduced solid waste (paper) and potentially
hazardous waste (film and processing chemistry).
* Reduced makeready times and reduced waste generation by
eliminating defective plates caused by misregistration, dust,
contact, and vacuum problems.
* Lower cost for short-run projects,
* Prepress waste eliminated.
Many printers and prepress shops have successfully integrated
digital technology to varying degrees. As digital methods are
integrated into prepress production, printers need not worry about
losing customers who do not use computers because conventional art
work can be digitally scanned into the system.
The most common drawbacks of direct-to-plate technology are:
1) plates that develop problems need to be re-imaged
2) desktop file problems, such as improperly set text
3) color management problems on the press can significantly reduce
press productivity.
Even with these drawbacks, the advantages of reduced labor, reduced
film costs and reduced makeready time on press still make direct-
to-plate a viable option for many printers.
"Medium and larger printers should begin exploring the implications
of direct-to-plate. The savings promise to be tremendous, and the
more files that go desktop, the more sense it will make. Careful
planning and exploration of technology options and work flow
redesign will lead to a productive solution when the time is right
for you," (White, Time 1994).
b. Digital Proofing
Traditional proofs show exactly what will be on the final product
because they are made directly from the films that will be used to
make the plates. Although film proofs are not perfect in color
representation, anyone experienced with reading proofs can judge
what is specified in the proof.
Traditional proofs are costly because they are labor intensive to
produce and materials are expensive. The largest cost to digital
proofing is the capital investment in equipment. Once integrated,
digital proofs are easily, quickly and inexpensively generated.
The largest growth area and the most cost-effective for printer and
customer is in intermediate or scatter proofs. Even if customers
distrust digital for the final proof, it is still cheaper and
faster to use digital proofs for approving type, position and color
breaks. Additionally, when customers have short runs, they may not
be willing to spend a lot of money to proof a color job if the job
is to be printed inexpensively on a short-run digital press.
"Speed, and especially money, are really underlying the move toward
digital proofing. (Hannaford 1994)."
The biggest disadvantages of digital proofing are the capital
investment in equipment and a few technical limitations. For
instance, currently no standard PostScript interface exists, so
files must be in standard high-end CEPS (Color Electronic Prepress
Systems) formats. Also, the product is only set for SWOP
(Specifications for Web Offset Publications) ink standards. New
technology integration will eliminate most of these disadvantages.
Currently, Kodak, 3M, and others have established direct digital
color proofing systems. Although the products are different, all
systems output proofs that are similar to analog film proofs with
color separations laid together and laminated to produce a
composite view. These are similar to traditional proofs and a
halftone screen can closely approximate the final output,
eliminating the need for hard copies. Color copiers and color
laser printers are also used to supply color proofs. This saves
time and money while reducing proofing waste.
c. Soft Proofing
Proofing can also be done on-screen via computer networks (soft
proofing). Images can be digitally transmitted by modem to the
client for approval or the client can come in to view the soft
proof. The limiting factor to soft proofing is the color accuracy
of the monitor. Monitors are available that are color correct.
This is a good way to approve layout, text and other parameters.
Once the soft proof is approved, the operator can output a digital
hard proof. If that is satisfactory, film can be produced for the
final off-press proof. Soft proofing reduces prepress waste and
saves time and money.
3.0 Printing Inks
Successful lithographic printing using both traditional water-based
processes and waterless technologies requires the press operator to
be part skilled craftsperson and part chemist. Lithographic ink,
fountain solution, water, substrate and press adjustment all play
a role in achieving the proper image. Fine tuning the balance
between these elements allows the press operator to produce salable
products. Inks are perhaps the most important aspect of the
overall process because different ink formulations impart different
characteristics to the ink and thus affect its performance in
relationship to the other press elements.
a. Ingredients
Lithographic inks are oil-based, allowing them to resist the
fountain/water attracting portions of the lithographic plate and
maintain the plate image. Traditionally, ink oils have been
petroleum-based, but ink manufacturers are continually developing
inks that substitute much of the petroleum oil with vegetable-based
oils such as soybean oil. The oil base or "vehicle" portion of the
ink serves to transport and bind pigments in the ink to the
substrate (Eldred, 1992).
Prior to the mid-1970s, pigment relied heavily on inorganic metals
to provide ink color (Hutchinson, 1986). These metals were often
present in amounts exceeding state and federal regulatory limits,
rendering waste ink hazardous.
State governments have further restricted the amount of metal
pigments allowed in printing inks, particularly for packaging inks
(REC, 1992). In response, ink manufacturers have developed organic
coloring replacements, many of which are not as heavily regulated
as the earlier metal compounds (Hutchinson, 1986). However, some
of the new pigments are manufactured from derivatives of benzene,
and sometimes still contain metals. A recent study analyzed the
presence of the heavy metals (cadmium, arsenic, mercury, antimony,
lead, and selenium) in lithographic inks. Although no single metal
exceeded 10 parts per million (ppm) in samples, levels for the
combined metals often exceeded 30 ppm and ranged as high as 39 ppm
(Donvito et al., 1992). Depending on the metal and the amount of
waste ink being generated, these levels often exceed regulatory
limits, making the waste ink hazardous.
Other ink additives include solvents, varnishes and dryers of
various kinds. All of these additives are used to control the ink
flow characteristics preventing pigment flocculation and to
accelerate drying (Eldred, 1992). Figure 3.1 lists some of the
common ingredients in printing inks, highlighting the ones most
likely to be regulated by state and federal environmental, health
and safety laws. With 1 million new ink formulations released each
year, it is impossible to list every ingredient used in every
printing ink (Dennis & Jenkins, 1991).
Figure 3.1. Printing Ink Constituents and Potentially Regulated
Constituents
* Vehicles/Varnishes; Commonly Used Chemical Formulations
[+] Rosin Esthers; Rosin and pentaerythritol
Long-oil alkyd; Phthalic anhydrite and glycerol
Phenolic resin; Phenol and formaldehyde
[+] Hydrocarbon resin; Ethylene, butadiene and indine
Modified resin; Maleic acid and maleic anhydride
Waxes; Natural and synthetic
Mineral oils; Natural and synthetic
Soya/vegetable; Linseed, tall, soybean and safflower oils
[+] Resin/solvent varnishes; Variety of hydrocarbon solvents
Drying oils; Alkyd, urethanes and phenolic resins
[+] Urethanes; Toluene diisocyanate and trimethylol propane
* Pigments
-- Organic Pigments:
Carbon black; Graphite
[+] Organically derived pigments: Rhodamines, AZO pigments;
Benzene, Napthalene and Authracene derivatives
-- Inorganic Pigments:
[+] Cyan blue and green shade cyan; Copper Phthalocyannine
Whites; Calcium carbonates, clays and titanium dioxide
[+] Yellows; Lead, chromium
[+] Reds; Barium
* Solvents
[+] Aliphatic hydrocarbons; Parfins
[+] Aromatic hydrocarbons; Benzene
[+] Alicyclic hydrocarbons; Cycloparafins, terpenes
[+] Co-solvent mixtures; Alcohols and hydrocarbons
Bolded constituents [+] may be regulated depending on concentration
and overall volume of wastes. Further, some constituents may be
regulated more heavily in one state and not another. Cheek with
your state environmental compliance office or technical assistance
office for more information.
Information for this figure derived from "Chemistry For The Graphic
Arts," Ellred, 1992. Environmental Law Index to Chemicals.
b. Regulations
Printing inks can contain material that makes them hazardous. The
EPA lists some chemicals as hazardous while other chemicals are
only considered hazardous if they exceed regulatory levels. In the
latter case, laboratory testing is required to determine if the
chemical concentrations constitute a hazardous waste.
The need for specific tests can be determined by examining the
Material Safety Data Sheets (MSDS) supplied by ink vendors, which
list potentially hazardous ingredients. Testing can be arranged
through analytical labs to determine if ingredients exceed
regulatory limits. Regulatory limits for hazardous components of
inks are listed in Appendix A.
Unfortunately, even if waste ink does not test hazardous, state
waste authorities and local landfill operators may refuse waste ink
shipments because of restrictions on accepting "free liquids" for
fear that petroleum-based inks may cause contamination. Thus, inks
may have to be disposed of by an EPA-licensed hazardous waste
management company. Additionally, depending on the amount of
hazardous wastes generated, each facility must meet requirements
for obtaining an EPA identification number as a generator of
hazardous waste, track the generation and disposal of hazardous
waste, monitor the hazardous waste storage area and accomplish
these tasks within specific time frames.
The 1990 Clean Air Act Amendments (CAAA) mandate implementation of
monitoring and control guidelines for a variety of hazardous air
emissions from specific industrial processes, including
lithographic printing. Nationwide, lithographers spend over $110
million annually to meet these requirements (ER, 1993). This has
focused the printers' and lithographic ink, fountain, and solvent
suppliers' attention on the volatile organic compound (VOC) content
of their inks, solvents, and fountain solutions. Petroleum-based
heat-set inks have higher VOC contents than soy/vegetable oil-based
heat-set inks, while electron beam and ultraviolet curable inks
produce no VOCs (Tellus, 1993).
The issue of how serious lithographic ink VOC emissions are, from
a regulatory standpoint, has been a point of contention in recent
years, and the new guidelines are expected to address this (Lustig,
1993). Nevertheless, for printers faced with controlling VOC
emissions from their operations, ink choice can contribute to or
help reduce emissions.
3.1 Reducing Waste Ink
Color changes, press cleaning and poor ink management such as
drying and skinning generate waste ink. Careful attention to good
operating practices, process changes and/or product substitutions
can decrease the amount of waste ink generated. Reduced disposal
costs, monitoring requirements and liability issues related to
waste ink generation and disposal will result. A comprehensive
list of approaches for each of these three categories is included
as Figure 3.2.
Figure 3.2. REDUCING INK WASTE
GOOD OPERATING PRACTICES
* Keep ink containers sealed and contents leveled; place plastic or
waxed paper on top of the ink to prevent oxidation.
* Scrape as much ink from empty cans as possible prior to disposal
or recycling of ink tins.
* If the firm is large enough, presses can be dedicated to specific
colors or as "hazardous inks" only presses, decreasing the number
of cleanings needed for each press.
* Use a standard ink sequence for process colors.
* Schedule runs from lighter to darker colors to decrease the
amount of cleaning necessary.
* Recycle light colors into darker and specialty colors.
* Return unused excess ink to the manufacturer.
* Improve accuracy in job estimation.
*( Segregate waste ink colors for recycling.
* carefully monitor inventory to assure that older inks are used in
a timely fashion and inks are only ordered if necessary.
* "Prethink" printing jobs and counsel customers about the
environmental impacts associated with particular color, paper, or
printing method choices. Make sure that print jobs reflect the
true cost of doing business and disposing of hazardous wastes.
PROCESS CHANGES
* Install an ink agitator or an ink leveller on the ink tray to
prevent premature oxidation of ink.
* Recycle waste inks in shop or through an ink recycling service.
* Use a computer controlled mixing program in conjunction with a
digital scale for mixing PMT colors.
* Use an anti-oxidant spray to prevent skinning of ink in the ink
fountain.
* Use a digital scale whenever measuring out ink for a job to
improve accuracy
PRODUCT SUBSTITUTION
* Vegetable/soy inks
* Electron beam curable inks
* Ultraviolet curable inks.
* Water washable ink systems
* Waterless inks
Testing, monitoring, assuring proper disposal and completing the
paperwork related to waste management activities requires
significant employee time and managerial support. This can
contribute to overhead costs, which must be considered in addition
to the waste ink disposal expense.
Good operating practices (GOPS) are often the most cost-effective
way to decrease the amount of waste ink generated. Using careful
and consistent GOPs requires building employee commitment and
interest in pollution prevention as well as managerial support to
encourage employee participation in pollution prevention programs.
GOPs include careful inventory control, and careful scheduling and
managing of jobs. Most GOP approaches focus on wise raw material
management and careful pre-thinking prior to running print jobs, so
work is accomplished with a low margin of error, decreasing waste
generation. A variety of GOPs are applicable to ink management.
These include:
* Keep ink containers sealed and contents leveled; place plastic or
waxed paper on top of the ink to prevent oxidation and spray ink
with an antiskinning agent.
* Scrape as much ink from empty cans as possible prior to disposal
or recycling.
* If the company is large enough, presses can be dedicated to
specific colors or to hazardous inks only, decreasing the number of
cleanings needed for each press.
* Use a standard ink sequence for process colors.
* Schedule runs from lighter to darker colors to decrease the
amount of cleaning necessary.
* Recycle light colors into darker and specialty colors.
* Return unused excess ink to the manufacturer.
* Improve accuracy in job estimation.
* Segregate waste ink colors for recycling.
* Carefully monitor inventory to assure that older inks are used in
a timely fashion and inks are only ordered if necessary.
* "Prethink" printing jobs and counsel customers about the
environmental impacts associated with particular color, paper or
printing method choices. Make sure that print jobs reflect the
true cost of doing business and disposing of hazardous wastes.
Process changes can be as simple as installing an ink agitator on
the ink fountain to prevent skinning or as complicated as
implementing an in-house ink recycling system (GATF, 1989).
Process changes usually require some equipment purchases and
employee training. Process changes include:
* Installing an ink agitator or an ink leveller on the ink tray to
prevent premature ink oxidation.
* Recycling waste inks in shop or through an ink recycling service.
* Using a computer controlled mixing program and a digital scale
for mixing PMT colors. These programs allow the lithographer to
custom mix any ink color from colors already in inventory. This
decreases the purchase of new colors and increases the use of
existing inventory. A digital scale makes the entire process more
accurate and decreases the amount of ink wasted as a result of
"guesstimation" errors.
To insure waste reduction benefits, it is important to buy inks
without dryers. Dryers should be added by the printer as needed.
Case study C describes one printers experience with computer
controlled mixing.
Case Study C: Ink Inventory Reduction By In-House Ink Mixing
Woolverton Printing Company, Cedar Falls, Iowa, is a full service
lithographic printer offering type and art, prepress, press and
bindery services. In a cooperative effort with the Iowa Waste
Reduction Center, John Lynch, CEO, and Mitch Weinberg, operations
manager, implemented an in-house ink mixing program for specialty
colors. Woolverton desired to reduce a high inventory of unused
inks and hoped to reduce the costs associated with purchasing new
ink colors by mixing its own inks. Lynch and Weinberg also
anticipated that increased attention to the amount of ink needed,
mixed, and used for specific jobs would improve the press
operator's accuracy and decrease ink waste.
With assistance from the IWRC, Woolverton was able to purchase the
basics needed to establish an in-house ink mixing program. This
included a computer program to describe the exact type and quantity
of ink needed to mix a specific specialty color from inventory
already on hand, the computer hardware needed to run the program
and print the recipes for specialty colors, and a digital scale
able to display weights in fractions of ounces or grams. This
equipment costs approximately $2,500 to set-up and install.
Once the program was installed, Woolverton employees could mix any
color needed for a specialty job from existing inventory. It also
allowed employees to mix fractional amounts using the digital scale
instead of having to mix whole pounds or ounces of ink.
IWRC staff members and Woolverton employees hoped to decrease
inventory, decrease waste ink generated and increase accuracy when
mixing inks required for specialty colors. To evaluate the
effectiveness of this program, an inventory was generated from a
series of 119 jobs without using the in-house ink mixing system.
Woolverton employees carefully recorded the amount of ink used and
wasted using the digital scale. Press operators then monitored an
additional 116 jobs using the in-house ink mixing program and
carefully recorded the amount of ink used and waste generated.
Employees also watched for a decrease in the inventory generated
from the original 119 jobs.
The in-house mixing program reduced inventory 40-50 percent. The
press operator was also able to more accurately gauge the amount of
ink needed for a particular job and; thanks to the digital scale,
measure the exact amount. However, the amount of ink wasted as
skins removed from mixing colors increased 17 percent when the in-
house ink mixing program was used.
Weinberg attributes the mixed results to a variety of factors. A
limited number of jobs were monitored with and without the ink
mixing program in place. It was also impossible to control the
types of jobs being monitored, The difference in the amount of ink
wasted could be a distortion resulting from these uncontrollable
variables.
When the ink mixing program was in place, a higher number of church
jobs came through requiring reflex blue which tends to form thick
skin faster than other inks. Additionally, all inks in stock at
Woolverton already have dryers added to them. Purchasing inks
without dryers and adding them when the color is mixed will
decrease the amount of waste skins.
Operator experience is also a factor. As press operators become
more adept at mixing their own colors and the shop superintendent
is able to plan ahead use as few mixing colors as possible to
achieve the desired specialty color, the amount of waste skins will
be reduced.
Overall, Weinberg was pleased with the inventory reduction and the
ink mixing program's user friendly characteristics.
"Even for the computer illiterate, this program is easy to use,"
Weinberg said. He believed that in-house mixing is well worth the
time and as press operators gained experience with the mixing
program and digital scale, they would reduce the amount of waste
skins generated. "Overall," states Weinberg, T I using the mixing
program is a lot easier than the old method of mixing one pound
increments of ink or ordering out specialty colors."
PHOTO [refer to source document]
* Using an anti-oxidant spray to prevent ink skinning in the
fountain. Readily available from ink vendors, these substances act
as physical barriers to oxygen, inhibiting the drying reaction.
Once the press is running, the anti-oxidant "burns off " on the ink
roller, greatly reducing or eliminating its effect. The inks can
then dry on the substrate.
* Using a digital scale whenever measuring ink to improve accuracy.
Many lithographers have been successful in reducing the amount of
waste ink generated by recycling it on site or by contracting with
a recycling service to blend it into darker colors for reuse.
Companies such as Semler Industries, Inc., Franklin Park, IL and
Resource Recycling and Remediation, Inc., Pittsburgh, PA sell
equipment designed to filter and distill waste inks for reuse
(Watson, 1988). Research has shown that when a company generates
100-200 gallons of waste ink per week and uses mostly dark colors,
on-site filtration, distillation and reuse are cost-effective
(Gavaskar et al., 1993). The recycled ink compares favorably to
new ink in tests for grind, residue, viscosity, tack, water
content, and water pickup.
Some ink recyclers also recycle waste ink on site (Logsdon, 1993).
Recyclers provide totes for process color segregation and produce
satisfactory final products. Once again, it is important that the
generator use sufficient ink quantities for this solution to be
viable.
Case Study D discusses one lithographer's experiences with such an
ink recycling service.
Case Study D: Ink Recycling to Go
Harry Brinkman, Director of Regulatory Compliance for MetroWeb, in
Earlanger, Kentucky, runs two full-web Heidelberg M-300's using
about 17,000 pounds of ink per month. Wanting to reduce waste ink,
Brinkman considered in-house and outside recycling options without
finding a service to fit MetroWeb's needs.
At a trade show, Brinkman discovered Pro-Active Ink Recycling, a
Canadian-based ink recycler that brings a mobile ink recycling unit
to facilities across the U.S. and recycles ink, mixed or color
separated, on site.
MetroWeb tried this service and realized the savings. By recycling
on site, MetroWeb can avoid the legal liabilities and paperwork
associated with off-site recycling or disposal. Additionally,
MetroWeb learned that by working closely with the technician, they
could produce recycled process colors very similar to unused inks.
Press operators were able to adjust the ink/water balance and
produce results comparable to new inks without experiencing
trapping problems.
"Pro-Active even helped us find reusable 3,000 pound totes to
supply ink to our presses," states Brinkman, "and they supply
color-coded storage containers for waste ink." By providing good
follow-up with press operators about waste ink segregation
practices and the costs associated with ink disposal, MetroWeb
achieved good adherence to waste collection and segregation
programs, which helps make it cost beneficial.
My cost per pound for new ink is $1.80 while the recycled ink costs
$1.05 per pound for nearly comparable quality, Brinkman said. And
this cost does not include the cost we previously paid for disposal
of waste ink. Service is excellent. I can call [Pro-Active] up
and they will work me into their schedule in a week or two."
While MetroWeb has had excellent success with its programs,
Brinkman has these words of advice for other printers: "Pro-Active
has been very good for us, but small quantity ink generators [under
100 gallons a month] should consider shipping waste to a recycler
and having it sent back." However, you lose a lot of control over
ink quality and processing when it is sent off-site. For larger
quantity generators though, "savings can be magnificent provided
you can work with someone who will work with you to produce a
product that runs [on the presses] well,"Brinkman said.
Material substitutions can decrease the amount of waste ink
generated. Many lithographers have successfully substituted
petroleum-based inks with electron beam curable (EBC), ultraviolet
curable (UVC), soy/vegetable, high solids and waterless inks to
decrease the toxicity and amount of waste ink. Material
substitutions will be presented in-depth but generally include
using:
* Vegetable/soy inks
* Ultraviolet curable inks
* Electron beam curable inks
* Water washable ink system
* Waterless inks
3.2 Soy/Vegetable Oil Inks
Soy and vegetable oil-based inks, especially linseed oil-based
inks, were once commonly used, but with the advent of high-speed
presses were replaced with faster setting petroleum-based inks.
The drying time of soy/vegetable-based inks has been one of the
major drawbacks to their use (PM, 1991). However, many printers
find that customizing dryers and using drying powders helps obtain
desirable results. Soy inks are 2-5 percent more expensive than
traditional petroleum inks.
Even though vegetable oil inks contain non-petroleum oils, a
certain percentage of the oil is still derived from petroleum.
Figure 3.2 lists the percentages of soy oil that various categories
of ink must contain to be certified by the American Soybean
Association (ASA).
Figure 3.2 Certified Soy Inks (NSIIC, 1994)
Ink Types; Required Percent Soy Oil
Heat-set Ink; 7% of Total Formulation Weight
Cold-set Ink; 30% of TFW
Business Forms Ink; 20% of TFW
Black News Ink; 40% of TFW
Color News Ink; 30% of TFW
Sheet-fed Ink; 20% of TFW
Soy inks have considerably lower VOC emissions than petroleum-based
inks based on EPA test methodologies, and they are manufactured in
part with a renewable resource: soy/vegetable oil. Some printers,
especially newspaper printers, have achieved increased coverage and
excellent color with most colors of soy ink except black (NSIIC,
1994).
Further, some sources claim that soy-printed products are more
readily deinkable by wastepaper processors and produce a less
hazardous sludge, making them more recyclable than petroleum
printed products (Rosinski, 1992; NAPIM, 1991). Case study E
describes a newspaper lithographer's experience with soy ink.
Case Study E: Switching From Rubber Based Inks to Soy Based Inks
Rapid Printing of Urbandale, Iowa, wanted to improve its workplace
air quality and decrease ink rub-off on finished products. Kevin
Brown, president and publisher, began working with the Small
Business Pollution Prevention Center (SBPPC) at the University of
Northern Iowa to implement a change from rubber-based ink to soy-
based ink in his printing operations.
Brown hoped to realize improvements air quality during press runs
but also improvements in print quality, decreased rub-off and less
failure in Rapid Printing's collator. The collator is an older
model machine that jams when rubber-based ink builds up on the
rollers.
Pat McMurray, press operator, carefully monitored his A-B Dick 360
and 385 presses during the switch, noting difficulties and/or
improvements in ink performance. The average press age was 20
years and both the 385 and the 360 used Grace poly-cell
compressible blankets. Impressions per run ranged from 500 up to
1,500.
McMurray discovered that the soy colors were more solid than the
rubber based product. Odor during press runs was significantly
reduced with the soy based ink, and the purchase cost was lower.
Clean-up also required less solvent. Time spent per clean-up job
was about the same for the soy and the rubber based inks, and
makeready was not significantly different. He also noticed that he
was cleaning the collator rollers less when using soy ink.
Problems arose with press runs of over 700 impressions using the
soy ink. Quicker drying caused toning on the plate and
necessitated more frequent press cleaning in addition to increased
fountain consumption. Certain colors, such as reflex blue, seemed
to dry more quickly than other colors. Runs of 700 impressions or
less, encountered none of these difficulties. McMurray is now
investigating having dryers custom blended or mixing in his own
dryers to eliminate the toning problem.
Ambient air quality tests indicated that, compared to the rubber
based ink, VOCs from the soy ink were greatly decreased. During
the longer runs when toning became a problem, VOCs from the
fountain were increased. Both Brown and McMurray hope that the
toning problem can be overcome by working with the ink supplier.
Overall, Brown was pleased with these initial results and would
like to continue working with the soy inks to improve their
performance. He felt that, the color quality of finished jobs and
the low VOC emissions from the inks warrant further work. He was
also pleased with customer inquiries about using new soy inks, "We
have had customers call because they were intrigued that we were
using soy inks," states Brown. "We definitely will consider using
only soy ink on our future jobs."
3.3 Ultraviolet and Electron Beam Curable Inks
EBC inks consist of low-molecular-weight polymers able to react
with a stream of electrons from a vacuum tube containing a linear
cathode which can generate several hundred kilovolts of energy
(ESI, 1994). The action of the electrons drives a polymerization
reaction which causes polymers to form and the ink to set. A
similar process cures UVC inks which react under ultraviolet-
spectrum light to complete the polymerization reaction and set the
ink (Eldred, 1992).
Both EBC and UVC inks will not cure until exposed to either
electron beam or ultraviolet energy. Therefore, they can be left
in the fountain overnight without skinning. This decreases both
press cleaning time and waste ink generation. Also, EBC and UVC
inks do not emit VOCs because they contain no solvents and they
eliminate the problem of "offset" in letterpress printing allowing
for high-speed press runs of up to 3,000 ft/min (Eldred, 1992;
Nahm, 1991).
Both UVC and EBC inks cost up to two times more than traditional
inks. Other drawbacks include high equipment capitalization cost
and potential worker exposure to X-ray radiation. A good EBC
starter system can cost $1 million, and more elaborate systems cost
as much as $5 million (Bartlet, 1994). Although cost-prohibitive
for the small printer, the systems work well for moderate to large
printing firms (150-200 employees) that can afford the initial
capital investment (Bartlet, 1994). Additionally, workers must be
protected from the X-ray energy produced by operating equipment
(Eldred, 1992; VDEQ, 1991). UVC systems are more affordable,
costing about $200,000 for equipment and installation (Bartlet,
1994). Although these systems eliminate VOCS, UV light generates
ozone and workers must be shielded from UV radiation. Still, many
lithographers using UVC systems are pleased with their performance.
Case study F describes the advantages of using UV inks.
Another drawback to using EBC and UVC inks and coatings is finished
products that are not easily recycled (Ungurait & Wolfe, 1991).
The high-molecular-weight polymers are harder for the traditional
repulsing systems to break down, making it difficult to obtain a
successful ink and fiber separation. Some sources claim that
recovered fiber is not as clean as with traditional or vegetable
oil-based inks, and as a result is only acceptable for lower grade
uses (VDEQ, 1991). Recent evidence, however, indicates that if the
deinking facility has more complex, cleaner equipment, a
satisfactorily recovered high-grade pulp can be produced (Tebeau,
1993).
Case Study F: The Use of Up Curable Inks
AGI, Inc., Chicago, Illinois, has been using UV inks since the mid-
to late 1970's, and CEO Wayne Fox cites environmental benefits,
ease of use, and time and effort savings as some of the reasons the
company chose UV. In addition, he says the UV inks have excellent
resistance to rub-off and set-off and provide the kind of long-
lived quality product needed by AGI's customers.
AGI, which runs a Plenatos Multi-Color press, two 55-inch 6-color
presses, and two 40-inch 6-color Heidelbergs, produces multi-color
covers for major-label compact disc manufacturers. Color
requirements and product durability are exacting in AGI's line of
work.
Waste in AGI's UV process is minimal if the inks are handled
properly, according to Wayne Fox. "Good management practices
almost eliminate the waste in our operation. What waste we do have
is sent out when a drum is collected for fuel blending." "It has a
very good BTU value and is used as a fuel for cement kilns," he
said. Since the inks do not polymerize until exposed to UV energy
sources, they can remain in the ink fountain overnight without
skinning.
Clean-up is no harder than with conventional petroleum-based inks,
state Simerson, press operator. Other than solvent used in clean-
up, the UV process does not release VOCs as the ink cures.
Fox believes that worker safety issues are adequately addressed by
today's equipment.
"Early systems left a couple inches gap between the UV source and
the substrate," explains Fox. Equipment manufactured today
completely shields the curing area, and if any of the shields are
raised while the unit is in operation, the UV source immediately
shuts itself off. Fox reports he has had no problems with ozone
from the curing process, and ozone has not been an issue in
obtaining permits for new equipment.
AGI has experienced an added benefit of energy savings by replacing
infrared curable inks with UV systems, which use about one-third
the energy and achieve the same if not better results, says Fox.
Aside from the benefits of faster production times, clear image,
and energy savings, Fox said, "I'd recommend UV for its
environmental benefits alone, especially if the company wants to
produce a durable, color graphic product."
3.4 Waterless Inks
Waterless inks and waterless printing are best discussed as a
complete system. The waterless printing process is covered in
Section 6.1. Waterless inks are high in solids and are designed to
function with a silicon based lithographic plate. They are not
necessarily less toxic or hazardous than other ink types, but the
waterless printing system as a whole generates considerably less
VOC emissions than traditional lithographic processes.
4.0 Dampening System
The dampening system on a lithographic sheetfed press provides fast
and complete separation of the image and non-image area of the
plate by making the non-image area unreceptive to ink. The
principal factors influencing fountain solution selection are inks,
plates, press speed, paper, temperature and relative humidity
(Dejidas, 1990). Fountain solution is basically composed of water;
an acid or base, depending on the ink used; gum or synthetic resin,
to desensitize the non-image areas of the plate; corrosion
inhibitors; and wetting agents, such as isopropyl alcohol or an
alcohol substitute.
4.1 Traditional Dampening Systems
Dampening systems can be contacting or non-contacting systems.
Fountain solution is transferred using rollers in conventional
contacting systems. Non-contacting systems use brushes or spray
bars to transfer the fountain solution from the reservoir to the
plate cylinder (Office of Air Quality Planning and Standards,
1993).
4.2 Reducing the Need for Alcohol in Printing
Isopropyl alcohol contributes to atmospheric ozone formation by
reacting with nitrogen oxides in sunlight. Using alcohol in
fountain solution is popular because it reduces surface tension and
leads to easier press control, more even dampening of the form
roller, faster evaporation, and reduced ink emulsification. The
result: less dampening solution is used and less paper, ink and
time are wasted (Dejidas, 1990). Lithographers use alcohol in
concentrations up to 35 percent with most presses ranging from 15-
20 percent (Office of Air Quality Planning and Standards, 1993).
This is much higher than several state and local regulatory
agencies will accept. Many restrict alcohol use to 3-8.5 percent,
while printers in geographic regions not meeting EPA standards are
required to operate alcohol free. Many companies, operating in
geographical regions with ambient air quality below EPA standards,
are required to remove alcohol from their fountain solutions.
Alcohol substitutes can reduce fugitive VOC emissions because less
of the substitute is used and they do not evaporate as readily
(Dejidas, Jr., 1992). Substitutes also extend roller life and
require less ink.
4.3 Pollution Prevention Opportunities for Dampening Systems
Fountain solution is generally replaced when ink color changes or
as part of routine maintenance. Waste fountain solution may
contain residual ink and, at some point during the printing
process, will release the volatile fraction of the solution.
Pollution prevention opportunities include:
* Eliminating alcohol fountain solution.
* Extending fountain solution life by adding filters, chillers and
recirculating systems.
a. Eliminating Alcohol from the Dampening System
Different presses use different dampening systems. The main types
are: open reservoirs, closed reservoirs that drip onto molleton-
covered rollers and central circulation systems that filter and
automatically meter fountain solution to the press. Fountain
solutions vary with differing systems. Case study G describes the
effect the dampening system can have on makeready.
Case Study G: Select Equipment Based on Printing Needs
A recent classroom study showed that makeready can be reduced
significantly with an automatic blanket dampener.
For this study, students at the University of Northern Iowa printed
four color separations; two colors using the traditional fountain
and molleton covered dampening system equipped on a 20-year-old
duplicator press , and two colors using an automatic dampening
system donated by Varn.
To quantify waste generation, students recorded, makeready sheets,
time, and fountain solution consumption. Subjective parameters
such as print quality and ease of use were assessed by the
students.
The first print demonstrated the students' inexperience with the
duplicator. Water balance was constantly a problem and paper were
lost in corrections. Print quality varied as the roller cover
dampness varied.
These problems were eliminated with the automatic dampening system.
Dr. Ervin A. Dennis, professor, remarked, "The dampening system
definitely creates less waste. Every printed sheet is usable. The
consistency of ink coverage, from start to finish, is excellent."
The small lithopress has manual ink key settings and plate
adjustment. Burdened without micrometer settings, makeready time
and paper waste is directly related to achieving registration and
proper ink density.
Given the limitations of the duplicator-press and the context with
which it is used, fountain solution consumption is the primary
measure of effectiveness.
PHOTO [refer to source document]
The molleton-covered dampening rollers used an average of seven
ounces each run. The automatic dampener used only two ounces.
The unit also exhibited a surprising 30 percent reduction in paper
waste to makeready and a 45 percent reduction in time to the first
printed sheet. Some of this was due to increasing press operator
experience.
Print quality also improved. When a heavy cover of ink was applied
with the molleton system, roller cover dampness was critical in
achieving a consistent application of ink across the plate. With
the automatic system, adjustments were necessary during the run,
but coverage was consistent.
Generally, quality printing can be achieved by using less than 5
percent alcohol or alcohol substitute. When selecting an alcohol
substitute, consider the ink, press type and printing constraints.
Alcohol substitutes are composed of glycols, such as ethylene
glycol, glycol ethers, cellosolve ethers or proprietary compounds.
These substitutes reduce the surface tension of the fountain
solution but have a more complex chemical structure and higher
boiling point than IPA-containing dampeners. To achieve the best
print quality without relying on alcohol, several factors must be
monitored and adjusted to accommodate the different fountain
solution properties.
Before changing the printing process, review how the affected
dampening system works. Consult chemical suppliers regarding
available options specific to the press model, dampening system,
ink roller wash, blanket wash and papers used. Provide a sample of
make-up water to the vendor to determine which products (fountain
solution, alcohol substitute, anti-foaming agents, etc.) are
compatible. Many manufacturers offer samples and technical service
to ensure successful printing with their products. Take advantage
of their expertise. Discuss changing the fountain solution with
the ink supplier as well, to prevent an incompatible selection.
Create a press log and record recommendations. Figures 4.1 - 4.3
provide examples of press log entries.
Figure 4.1: Press Log Entry: Existing Press Conditions
Press: Heidelberg; Dampening System: Alcolor dampening with Royse
Refrigeration System.
Model: 19X25 MOZ 2-color; Roller Hardness; Dampening roller: 25
Press Age: 1988; Roller Age: 3 years
Cleaners: Metering Rollers: 25 units
Blanket Wash: XYZ WASH; Roller Age: 3 years
Roller Wash: XYZ WASH; Fountain Solution: XYZ Litho Etch
Press Wash: XYZ WASH; 15% Isopropyl Alcohol
Figure 4.2. Press Log Entry: Press and Chemistry Manufacturers
Recommendations [refer to source document]
Figure 4.3. Press Log Entry: Optimum Fountain Solution Mix [refer
to source document]
Adjust the dampening roller pressure setting and plate-to-blanket
pressure to accommodate the substitute's different surface tension
and viscosity. Check durometer readings for inking and dampening
form rollers. The press manufacturer can assist in determining
proper settings, though it is recommended that the metering roller
durometer be reduced to 18-22.
When first using an alcohol substitute, follow the manufacturer's
mixing instructions. Use the smallest amount indicated in the
instructions and measure the mixture's pH and conductivity. Record
these measurements in the press log. This becomes the reference
point. Print with this mixture, recording observations about its
performance. Note how the plate rolls up, how the press starts
after feed trips, if excess fountain solution is used to keep the
plate clean, and if the metering roller is picking up ink. The
vendor can provide further suggestions and clarification as needed
(Dejidas, Jr., 1992). Adjust concentration and print again until
the optimum mix is achieved. When optimum performance is achieved,
note the concentrations of fountain solution, water and alcohol
substitute. Use this information as a reference for standard press
operation. Experiment with alcohol substitutes on one press at a
time and phase in additional presses when the previous one is
running smoothly. Keep the press log current, noting maintenance
schedules, problems and solutions.
Conductivity and pH can be used to predict fountain solution
quality. Conductivity is the ability to transmit an electrical
charge and is proportional to the ionic concentration in the
solution. (See Figure 4.4) Measure conductivity of the water and
fountain solution mixture, increasing the fountain solution
concentration incrementally and graph the values. The graph
provides a visual means to estimate fountain solution concentration
based on conductivity. Alcohol and alcohol substitutes affect
conductivity, so when the optimum mix is determined, measure
conductivity again. If using alcohol, remember that during a press
run, the alcohol will evaporate. Alcohol substitutes evaporate
slower than water; so during a pressrun, water may need to be
added.
Figure 4.4. FLOW CHART [refer to source document]
Conductivity increases during a press run because impurities, such
as ink and paper, are picked up by the dampening system. Measure
conductivity on a daily basis. When problems with print quality
arise, re-measure fountain solution conductivity. This can help
predict print problems resulting from fountain solution quality.
The pH of the fountain solution affects print quality. (See Figure
4.5) As the pH becomes more alkaline (7-14), the ability of the gum
to desensitize the non-image areas decreases, causing "scumming"
where the ink replaces the gum on the plate. When the pH drops,
the acid reacts with the dryer, making it useless as a drying
stimulator (Dejidas, Jr., 1992).
Figure 4.5. FLOW CHART [refer to source document]
Measure the fountain solution pH. Record in the press log and
determine the optimum range for printing. Figure 4.6 provides an
example of a conductivity and pH press log entry.
Figure 4.6. Press Log Entry: Monthly Monitoring of Conductivity
and pH
WEEK; Mon; Tue; Wed; Thur; Fri; Sat; Notes
1 Cond.; 1580; 2050; 1565; 2300; 2400; 1630; Changed Filters on
Recirculating Unit Fri
1 pH; 3.94; 4.30; 4.03; 3.82; 4.46; 3.8
(+/-); +; +; +; +; +; +; Print Quality
Though the pH of the paper should only have a minimal impact on the
fountain solution's pH, it's helpful to know the type of paper,
alkaline or acid, used for each job in the event of a problem.
Alkaline paper is produced using a process that includes calcium
carbonate. During printing, the calcium can accumulate in the
fountain solution, raising the conductivity without affecting pH.
Calcium buildup can create print problems including scumming.
The conductivity of the incoming water affects the performance of
alcohol substitutes. In areas with hard water (water with high
mineral content), conductivity readings may be as high as 300
micromhos/cm. (A micromho is a measure of electrical conductance).
Some water supplies may have widely varying hardness where
conductivity readings vary more than 80 micromhos cm. Water
filtration systems are recommended to eliminate problems that
alcohol addition formerly masked (MacPhee, 1990).
Water softening systems exchange magnesium and calcium carbonate
with sodium carbonate. This form of treatment is effective in
eliminating calcium or magnesium salt deposits from spray bar
dampening systems or nozzle tips.
Deionizing units remove minerals and salts from the water, reducing
conductivity to less than 50 micromhos. This can change pH
depending on the deionizing unit used. These are recommended if
water supply quality is highly variable.
Reverse osmosis units remove salts, minerals and organic matter
from the water. This treatment reduces conductivity to 50
micromhos or less and the pH should be neutral. These units are
recommended for water supplies of variable quality as well.
Reverse osmosis units include a water softening unit, carbon
filters to remove organic matter, and a micro-membrane to remove
sodium carbonate. Reverse osmosis units tend to cost more than
deionizing units but have less operating costs.
Water temperature can vary from one side of the fountain tray to
the other, affecting viscosity and ability to cover non-image areas
of the plate. Low flow may result from clogged lines or improperly
routed lines (MacPhee, 1990). Measure the temperature of t
fountain solution across the pan. If i varies more than two
degrees (+/-), check the flow rate into the water pa Case study H
describes one printer's experience with reducing and eliminating
their use of IPA.
Case Study H: Selecting Alcohol Substitutes
Woolverton Printing Company, Cedar Falls, Iowa, wanted to reduce
VOC emissions to improve interior air quality and meet
environmental regulations being drafted by the EPA. Mitch
Weinberg, operation manager, learned about alcohol free printing.
With the assistance of the Iowa Waste Reductio Center, Woolverton
began testing low VOC fountain solutions.
Woolverton's three, two-color Heidelberg presses are equipped with
chilled and filtered, recirculating fountain reservoirs. Since
installation, Woolverton had never discarded fountain solution.
Never changing the fountain solution meant Woolverton began adding
more alcohol to "fix" print problems, averaging 15 percent alcohol
in the fountain solution.
Consistent water quality eases the reliance on alcohol in the
fountain solution. As an industry partner, the IWRC installed a
reverse osmosis water treatment system. Cedar Falls' water supply
has a high concentration of calcium.
With the installation of the water treatment system, Woolverton
reduced the alcohol content to 5 percent because calcium carbonate
was removed from the water. Calcium carbonate acts as buffer,
requiring more fountain solution concentrate to achieve the desired
pH. The reverse osmosis unit also provide water with a consistent
conductivity, allowing this measurement, in addition to pH, to
predict the quality of the fountain solution.
For this study, Woolverton printed 45 jobs. All used low VOC
fountain solutions designed to be used with water with low mineral
content. The first 15 used water treated with a water softener; 15
used water treated through reverse osmosis and 5 percent alcohol in
the fountain solution; and 15 used water treated through reverse
osmosis, alcohol substitute, and fountain solution.
The softened water had a conductivity of 700 micromhos and required
a large, amount of fountain solution to bring the pH into the
recommended range of 3.8-4.2. During this run, the amount of
fountain solution necessary to bring the pH into the recommended
range suddenly spiked and caused print quality problems.
Traditional trouble shooting focused on cleaning rollers, changing
ink and adding alcohol. When reformulating fountain solution,
press operators discovered that the water softener exhausted the
sodium supply. Once recharged, the water quality stabilized and
the print quality improved.
The reverse osmosis unit achieved acceptable print quality using
only 5 percent alcohol without any major modifications.
Conductivity ranged from 1200 to 3050. Conductivity readings may
vary for several reasons including: temperature of the fountain
solution when the measurement is read, calibration of the meter,
concentration of alcohol and effectiveness of the charcoal filter.
As a result of the conductivity variability, Woolverton determined
fountain solution quality by measuring both conductivity and pH.
Alcohol free printing requires many changes. Trade associations
recommend using softer rollers, tight control of roller settings
and water feed rate. Furthermore, when fountain solution is
recirculated, printers are encouraged to measure conductivity and
pH to predict fountain solution concentration and quality.
Before the 15 runs with the alcohol substitute Woolverton replaced
the water pan metering roller with one of a lower durometer
reading. The press manufacturer recommended a durometer reading of
25, slightly higher than published recommendations. Once the press
was equipped, Woolverton began testing fountain solution mixtures
to find the optimum mix. After much trial and error, they found
that a mixture of one gallon of water, two ounces fountain solution
concentrate, and two ounces alcohol substitute was determined to
give the best print quality.
Woolverton followed the published recommendation to create a
conductivity curve of the fountain solution. This is important
because both the fountain solution and the alcohol substitute have
a vapor pressure lower than water's and will not evaporate like
alcohol. Over time, Woolverton should see a general increase in
conductivity and will need to add water. The conductivity can be
correlated to fountain solution concentration and help predict when
water should be added.
Once the optimum mix was determined, the conductivity ranged from
1890 to 2450. The conductivity readings are still influenced by
temperature, calibration, and filter performance. When using the
conductivity curves to predict fountain solution concentration, a
printer must standardize when a measurement is made, check
calibration daily, and note filter changes to determine if filter
age is a factor.
Even while adjusting the fountain solution/alcohol substitute
ratio, Woolverton was printing successfully. The first press run
demonstrated the second factor influencing the success of printing
without alcohol: roller settings. The press was not achieving
proper half-tones. Formerly, the press operator would assume that
the screens were not cleaning up properly and adjust the water feed
rate. The next run had proper half-tones, but black ink density
was too low. The PMT negative was checked to determine the correct
half-tone. The operators adjusted the rollers, and achieved good
print quality. Monitoring roller settings became part of routine.
Woolverton recognizes the value of flexible press operators willing
to try new products. "Before, the press operator would use alcohol
to cover up little problems but then spend half a day trouble-
shooting a problem when all the little ones added up," said Mitch
Weinberg.
Giving the press operators the tools to measure fountain solution
conductivity, pH and roller settings based on paper type makes
them more involved in the print process. When a problem comes
along, like roller settings, minor changes can be made that prevent
the loss of valuable time later.
Despite the success Woolverton has had with the alcohol free
fountain solution, its testing is not complete. All three
Heidelbergs have different dampening systems. Woolverton intends
to try other products even though the first alcohol substitute
worked.
The following suggestions may help correct problems that can occur
when using an alcohol substitute:
1.) Clean presses thoroughly. Carefully select cleaners that are
effective for inks and fountain solution used. If rollers are not
cleaned sufficiently between uses of different alcohol substitutes,
stripping can occur. When this occurs, certain areas of the roller
become more sensitive to ink and apply an inconsistent ink
thickness. For older presses, copperizing the rollers may
eliminate the problem. For newer presses with nylon- or teflon-
covered oscillator rollers, flush the ink rollers with warm water
after cleaning (Dejidas, Jr., 1992).
Brush dampener systems need the brushes cleaned frequently to
prevent increased water feed rate to compensate for dirt. Keep
brush guards in place and use white rollers so soiling is visible
(MacPhee, 1990).
2.) Control the water feed carefully. Excessive water feed causes
emulsification and poor performance. Some presses will flood the
inking system if the dampening system is left on when the paper
feed stops. Reducing the nip between the chrome roller and form
roller to run alcohol substitutes compounds this problem.
3.) Check the pressure settings of all rollers. Check both the
dampening roller pressure setting and the plate to blanket pressure
settings. Include the optimum settings in the press log for
reference.
4.) Inspect the chrome roller for pitting or ink sensitivity.
Pitting can cause an uneven water feed rate across the press and
pitted chrome rollers should be replaced (MacPhee, 1990).
5.) Check the metering roller for ink sensitivity or salt deposits.
Alcohol substitutes can affect water receptivity of the chrome and
metering rollers. When this happens, etch the chrome roller with
a solution of I ounce phosphoric acid to 32 ounces gum. Water
receptivity of the metering roller is maintained by applying gum
(Dejidas, Jr., 1992).
Some fountain solutions encourage salt deposits on the metering
roller. When this happens, back the metering roller away from the
chrome roller and clean it. A water softener could eliminate this
problem if the mineral content of the water is above 300 micromhos.
6.) Check the hardness of the metering rollers. Banding or grind
marks (comb-like or corduroy-like marks on the substrate in the
direction of paper flow) can occur if the metering rollers are too
hard or if the fountain solution is not mixed correctly. Softer
rollers or rollers with a slightly grained surface can prevent this
problem. Consult the press manufacturer and fountain solution
vendor for optimum roller hardness. Continue monitoring roller
hardness. When the durometer reading varies by 10 points beyond
the recommended range, replace or recondition the roller (MacPhee,
1990).
Rollers harden over time and a combination of age and glazing can
render the rollers ineffective. Deglazing rollers should reduce
the roller hardness by five durometer points (Schneider, Jr.,
1989).
Efforts to track the condition of press hardware can also be
recorded in the press log as shown in Figure 4.7.
Figure 4.7. Press Log Entry: Inspection Items [refer to source
document]
b. Extending the Useful Life of Fountain Solution
Filters can be installed on recirculating units serving one
fountain pan or as large central units supplying fountain solution
to multiple presses. Filter media can be as simple as a charcoal
or polypropylene filter, or involve a mixed media, free flow
design. Depending on individual needs, select filters to remove
gross contamination (including paper-dust and lint). The filter
media should remove ink residue as well, extending the life of the
solution.
A refrigeration unit will reduce evaporative losses, even when
using alcohol. Optimum fountain solution temperature is 50-55 deg
F (Dejidas, Jr., 1992). The EPA estimates that reducing the
temperature of fountain solution from 80 deg F to 60 deg F can
reduce alcohol consumption by 44 percent (Office of Air Quality
Planning and Standards, 1993). If an alcohol substitute is used,
it will increase viscosity. Be careful not to overcool the
fountain solution because ink will become tacky and cause picking
or piling problems. Clean condenser coils regularly.
An automatic mixing system can accurately mix fountain solution to
the proper concentration and eliminates monitoring conductivity,
although, it is impossible to determine the actual concentration of
the alcohol substitute in a fountain solution.
Some geographical regions have problems with organic growth in
recirculating systems and require stringent cleaning. Ultraviolet
light reduces algae, waterborne fungi and bacterial growth. The
traditional method of preventing organic growth in the
recirculating unit is to clean it with a 10 percent bleach wash
followed by numerous rinses.
Foam-free recirculating systems are available. These systems, if
compatible with the press, eliminate foaming without anti-foam
agents. Contact press equipment manufacturers, fountain solution
vendors or graphic arts associations for recommendations. This is
a specific concern when using alcohol substitutes.
5.0 Press Cleaning
A press in good repair is essential to meeting pollution prevention
goals. In addition to preventative maintenance, regular cleaning
is also necessary to keep the many moving parts operating. While
it is easy to collect and recycle the used press oil for rerefining
or energy recovery, minimizing solvents from press cleaning
presents more of a challenge.
5.1 The Role and Composition of Press Cleaners
Cleaning solutions are predominantly petroleum based, are often
mixed with detergents and water, contain up to 100 percent VOCs and
can be used as a multipurpose presswash or for cleaning just one
part. One general cleaner is not always effective for cleaning
rollers, blankets and the outside of the press.
Blanket cleaning consumes approximately two-thirds of cleaners used
on a press and is performed once or twice a shift, between jobs and
as needed to improve print quality. These cleaners must remove
excess ink and dry quickly without leaving any oil residue.
Remaining cleaner is used for cleaning press rollers (Office of Air
Quality Planning and Standards, 1993).
Cleaners used on chain and ink rollers should be less volatile so
solvent moves over all rollers before evaporating. For metal press
parts, slower working solvents are as effective as a general press
wash. Stronger solvents are needed for intermittent cleaning of
hardened ink, or for specific purposes such as etching the
chrome roller.
Define cleaning needs to select the best alternative cleaners and
cleaning methods to reduce VOC emissions.
5.2 Cleaning Wastes and Alternatives
Cleaning the press generates several wastes:
* Waste cleaner with residual ink
* Waste ink from the ink fountain
* Rags containing cleaner and ink
* VOC emissions from cleaners
Manage petroleum-based solvents and inks as hazardous waste. Some
inks may not be hazardous when discarded but are unacceptable for
landfilled disposal because they are viscous. Most states require
that a waste be tested to verify that it is non-hazardous and also
solid for landfill acceptance.
Disposable rags may be landfilled if laboratory testing
demonstrates that they are non-hazardous. Launderable rags are not
subject to hazardous and solid waste regulations because they are
reused after cleaning.
Press cleaning releases VOCS. Intentionally evaporating used
solvent is illegal disposal of a hazardous waste and subject to
penalty. Additionally, it exposes employees to hazardous working
conditions.
Chemical manufacturers are developing low VOC cleaners. just as
there are many different presses, there are many different
cleaners. Most low VOC cleaners still contain naphtha and average
3.5 pounds per gallon of VOCs and have a flashpoint greater than
200 deg F. "Quick drying" cleaners may have slightly higher VOC
content and usually have a flashpoint below 140 deg F, making them
hazardous waste. Some substitutes present a two step approach,
using a cleaning solution with a higher VOC content as step one to
be immediately rinsed with a low VOC cleaner as a second step.
Consult proposed and enacted regulations regarding low VOC cleaners
to ensure compliance.
Low VOC products continue to clean more effectively, but because
the first cleaners performed poorly, the industry has not readily
accepted them. EPA research has demonstrated successful
substitution of low VOC cleaners using an integrated approach.
Cleaning equipment, targeted product substitution and changing
operator practices can reduce VOC from cleaning.
5.3 Reducing VOC Emissions from Cleaners
Almost 50 percent (by volume) of high VOC cleaners evaporate before
cleaning (US EPA, 1993). Substitute cleaners, containing no more
than 30 percent VOC by weight have lower vapor pressure and higher
flash point than traditional cleaners but may not effectively clean
all areas of the press (Office of Air Quality Planning and
Standards, 1993).
The EPA estimates that it will cost the printing industry $110
million annually to implement VOC control guidelines for
lithographers (Environmental Reporter, 1993). Many control
technologies require equipment to capture and destroy emissions.
If a company can reduce emissions using product substitution or
process change, the expense of the air pollution control equipment
may be eliminated.
Allocating time for employees to experiment with substitute
cleaners and creating press procedures that use low VOC cleaners is
an investment in cutting control technology costs to meet air
emission standards. Feedback from employees and constructive
suggestions will create an effective pollution prevention program.
a. Equipment to Reduce Cleaning Needs
Automatic cleaning systems reduce cleaner consumption by removing
excess ink. These systems prevent ink buildup which requires
stronger cleaning solutions. When used properly, they also reduce
wasted time and lost impressions. One report cites that lost
impressions were reduced from 1,200-3,000 to 250-350 (Hanna, 1990).
An automatic blanket cleaner is comprised of a control box, a
solvent metering box for each press unit and a cloth handling or
brush unit. Many larger presses are equipped with automatic
blanket cleaners and older presses can be retrofitted. One company
manufactures a unit that uses a rotary oscillating spray and brush
device with solvent recovery. It is an enclosed system designed to
reduce overspray and eliminate wipe-up towels.
Roller wash-up blades and ink blades remove residual ink from
specific rollers, reducing the amount of cleaner needed. The
roller and wash-up blades' condition influence how well both stay
clean. The blade's angle against the roller should be adjusted to
apply sufficient pressure without being grabbed or pulled under the
roller. Press speeds should be just slow enough to allow for
thorough cleaning. Slower press speeds require more cleaner(Hanna,
1990).
To respond to special needs, presses can be equipped with
specialized form rollers (such as oscillating or hickey-picking)
instead of standard form rollers (Schneider, Jr., 1989).
Specialized rollers reduces press operator dependency on squirt
bottles of cleaners.
Automated press control systems improve productivity and reduce
makeready as well as cleaning needs. Systems that adjust ink/water
ratio, ink density and image density on the plate eliminate the
repeated cleanings between press operator adjustments.
High quality optics and computer control systems allow automatic
plate scanners to determine the relative density of the printing
image across the plate's surface. This data can be transferred to
an automatic ink key setting system, adjusting the ink profile for
each ink slide position. Automatic registration uses optical
scanners to locate the registration marks and set this position for
the duration of the press run.
One manufacturer has developed an optical system that detects the
ink/water ratio. Because both water feed and ink keys are part of
the system, any deviation of the ratio is detected and can be
corrected. The system correlates the refraction of light from the
ink form roller with the amount of water emulsified in the ink
(Jacobs Engineering, 1989). This system could also help encourage
the transition to successful alcohol-free printing.
b. Product Substitution
Low VOC blanket and roller washes generally contain naphtha,
inorganic phosphates and proprietary compounds. Many formulations
are totally proprietary and their ingredients are not listed.
Contact manufacturers to discuss your cleaning needs. Consider
ink, paper, fountain solution and the type of press. Request
samples. Many manufacturers provide technical assistance to ensure
successful product use.
Do not judge low VOC cleaners by the performance of one product.
Try a variety of different formulations. Follow the manufacturer's
recommendations. Most formulations require less cleaner than
naphtha based cleaner. Excess amounts will cause color problems on
the press.
Target cleaners for a specific purpose. A low VOC cleaner
effective on ink trays and metal parts may not be an effective
blanket wash.
When selecting a new product, determine your specific pollution
prevention goals you wish to attain. Review the product's material
safety data sheet for hazardous constituents (i.e. naphtha; 1,2,4,
trimethylbenzene), the flashpoint (if less than 140 deg F the
material becomes an ignitable hazardous waste when discarded) and
the VOC content, either expressed as a percent (preferably less
than 30) or in pounds of VOC per gallon
of solution.
The volume of low VOC cleaner should not be compared to the amount
of traditional cleaner used to do the same job. Even if it takes
more low VOC cleaner to effectively clean the press, the actual VOC
emissions will be less because it has a lower vapor pressure as
well as less VOC content and does not readily evaporate. Most
manufacturers caution that less cleaner is required when used
properly.
Follow manufacturer's cleaning directions for new products. If the
products are not used as intended, more will be needed to clean the
press. Low VOC cleaners tend to be water-soluble or water-miscible
and often require a water rinse following cleaner application.
Although this may take more time than traditional cleaners, the
rinse also removes paper-dust and lint.
Be careful when cleaning directions recommend "immediately rinse"
or "let product work into ink." Immediate rinsing may be necessary
to prevent a blanket wash from leaving a film on the blanket. Low
VOC roller cleaners may need time to loosen excess ink to
effectively clean. Warm water is usually more effective for
rinsing cleaners. If minerals build up, examine the rinsewater
quality before blaming the cleaner.
c. Procedural Changes Reduce Cleaning Wastes
Clean presses as needed, not on a schedule. Immediate cleaning and
using automatic systems will minimize cleaner consumption and
prevent buildup of ink, paper-dust or lint that will affect print
quality. When ink builds up, stronger cleaners become necessary.
Use the smallest amount of cleaner possible. Apply the cleaner to
the rag instead of pouring it over the part which wastes cleaner.
PHOTO [refer to source document]
If cleaners must be poured over rollers or press parts, use a catch
pan beneath the part (like roller trays) and empty the used cleaner
into a closed container as soon as the rollers are wiped. Store
used cleaner by color for future blanket and roller cleaning.
Store all volatile cleaners in closed containers. Make low VOC
cleaners readily available at each press. Store high VOC cleaners
in another area and tell the press operator to use it only for
specific purposes such as color change.
Do not leave an open funnel in the waste drum. Open funnels allow
the container to continuously emit VOCS. This is also considered
an open container under hazardous waste regulations. Remove funnel
and close drum when through.
Collect used rags in a self-sealing, flame-resistant can. Use
launderable rags instead of disposables. As long as the rags are
wet, not soaked, laundries will accept them for cleaning.
Remember, laundering the rags does not eliminate the waste, but
transfers it to the laundry's waste stream.
Schedule jobs by color. Clean the ink tray only when changing
colors.
Sequence colors from lightest to darkest: yellow, magenta, cyan,
black. Sequencing reduces cleaning and prevents a darker color
from bleeding through the lighter color. Sequencing also reduces
fountain solution changes if the press does not have a filtration
unit. Case study I describes a recent innovation in easy to clean
ink/solvent systems.
Case Study I: Engineering A Solution
Deluxe Corporation, a check printing company with 55 facilities
throughout the country, responded to stricter environmental
regulation and employee health and safety concerns by designing
water soluble inks and cleaners that eliminate fugitive volatile
organic compound (VOC) emissions. Deluxe, a large company with the
resources to perform research and development, evaluated the
relationship of lithographic ink and press wash. It developed and
patented a pantone-licensed line of water soluble inks and solvent-
free, non-VOC containing roller wash.
Most companies do not have the resources or expertise to research
and develop their own custom chemistries. They can, however,
benefit from the work of larger companies. Deluxe Corporation's
approach is one that can be emulated in even the smallest print
shop using commercially available products.
Deluxe Corporation set an environmental goal to meet the EPA's
proposed Control Technique Guidelines (CTG) mandated by the Clean
Air Act of 1990. The draft CTG calls for blanket and roller wash
to be formulated with less than 30 percent by weight of VOCS. As
part of its search for a solution, Deluxe Corporation experimented
with commercially available cleaners.
Petroleum based press washes were most effective, but also
contained the highest percent by weight of VOCS. Deluxe tested
available low VCC washes and discovered the cleaners were not
always compatible with the inks or presses. At that point, Deluxe
reviewed its entire lithographic process and performance criteria
for cleaners. Instead of just substituting cleaners, Deluxe
reviewed the relationship between the inks and cleaners then
developed the idea of an ink that changes solubility in water.
Deluxe Corporation's inks use standard pigments that include copper
and barium. The carrier is 100 percent vegetable oil. Waste ink
and rinse water from cleaning the press or ink trays is collected
at each of the Deluxe facilities. Because the solubility of the
oil phase of the ink is reversible, it can be filtered to remove
the pigmented vegetable oil portion from the aqueous phase. This
aqueous portion should be acceptable for sewer disposal. The
remaining ink residue may not be a hazardous waste but is not
recommended for landfill disposal.
Deluxe is currently evaluating the impact of these water-soluble
and water-washable inks and cleaners on a selected commercial
laundry's effluent. If the effluent meets discharge limits
established by the wastewater treatment plant in accordance with
the Clean Water Act, then Deluxe Corporation can conclude that the
inks and cleaners are less toxic and will meet future revisions to
environmental regulations.
Deluxe has realized other benefits from the new ink and cleaning
system, including dramatic reduction in worker exposure to VOCS.
Using a mass balance approach recommended by the EPA, Deluxe has
measured a 50-70 percent reduction in VOCS. Expected benefits from
removing the solvents in the inks include reduced wear and
plasticizer removal of the rollers. Water rinse which removes
paper-dust prior to press runs, may be eliminated because the inks
and cleaners are themselves water based.
Deluxe Corporation met the challenge of complying with
environmental regulations and accepted the responsibility to re-
evaluate its waste management in light of the new wastes generated.
Changing to comply with environmental regulations demands the
commitment, patience, and flexibility displayed by Deluxe when it
experimented with alternatives. One result of its commitment is a
water-soluble and water-washable ink and cleaning system that may
offer environmental benefits to other businesses.
5.4 On-Site Cleaner Recycling
Some printers use a solvent sink to wash sink trays. These sinks
circulate a solvent (generally naphtha-based) for quick, complete
removal of residual ink. These sinks are usually serviced by a
hazardous waste management company that replaces the used solvent
with new solvent according to a set time schedule. The hazardous
waste management company may recycle the solvent through
distillation, reclaiming the purified solvent and disposing of the
hazardous still bottoms.
Distillation involves heating the dirty solvent to its