United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/OOO/SR-95/081
June 1995
EPA Project Summary
Performance Demonstrations of
Alternative Screen Reclamation
Products for Screen Printing
Cheryl Keeman, and Paul Randall
Environmentally preferable products
for the screen reclamation process in
screen printing were evaluated by print-
ers during month-long demonstrations
at 23 printing facilities nationwide.
Screen reclamation is the process
where the ink and image are removed
from the mesh in order to reuse the
screen for a different image. Through
the Environmental Protection Agency's
Design for the Environment program,
performance characteristics of alterna-
tive screen reclamation products were
demonstrated. Manufacturers submit-
ted ten "product systems" for evalua-
tion. Each product system included the
three chemical products commonly
used to reclaim a screen: an ink re-
mover, a stencil or emulsion remover,
and a haze remover. Additionally, one
ink remover and two substitute tech-
nologies were demonstrated.
Performance of the alternative chemi-
cal systems was evaluated in two
phases: (1) laboratory testing to en-
sure the products were generally effec-
tive, and (2) in-field demonstrations.
Product evaluations from the field were,
in large part, subjective and reported
results relied on the experience and
judgment of the printers using the prod-
ucts. In general, most emulsion remov-
ers worked very well, but the success
with the ink and haze removers was
mixed.
Costs of switching from a baseline
reclamation system to an alternative
system were estimated. These costs
included: chemicals, labor, rag use, and
waste disposal. Based on this cost
analysis, 14 of the 23 volunteer facili-
ties would realize reduced screen rec-
lamation costs if switched from the
baseline to an alternative product sys-
tem. The other 9 facilities would expe-
rience increased costs.
This Project Summary was developed
by EPA's National Risk Management
Research Laboratory, Cincinnati, OH,
to announce key findings of the re-
search project that is fully documented
in a separate report of the same title
(see Project Report ordering informa-
tion at back).
Introduction
The objective of the Screen Printing
Performance Demonstrations was to pro-
vide critical information on the performance
of environmentally safer screen reclama-
tion products and technologies for the De-
sign for the Environment (DfE) Printing
Project. The goal of the DfE Printing
Project is to encourage printers to use
risk and hazard information, along with
performance data, to make informed, en-
vironmentally sound decisions about the
chemicals and processes they use. This
non-regulatory, voluntary project is a co-
operative partnership between the EPA,
the Screen Printing Association Interna-
tional (SPAI), printers, and manufacturers
of printing supplies. As one of the initial
tasks for this project, industry representa-
tives selected screen reclamation as the
focus area for the DfE project.
In support of the EPA Office of Re-
search and Development (ORD), the DfE
staff within the Office of Pollution Preven-
tion and Toxics (OPPT) conducted the
-------
Performance Demonstration portion of the
DfE Printing Project. Substitute products,
voluntarily supplied by manufacturers, were
evaluated for their ability to efficiently and
effectively clean screens. This performance
information was an essential element the
final project report, titled Cleaner Tech-
nologies Substitute Assessment (CTSA),
EPA document number EPA744R-94-005.
The CTSA integrates these performance
data with information on the costs, risks,
and hazards associated with the products
demonstrated.
Performance data on alternative screen
reclamation products were collected dur-
ing demonstrations carried out between
January and April 1994 and include infor-
mation such as time spent on screen rec-
lamation, volume of product used, and
appearance of the screen after reclama-
tion. Performance data came from two
sources: laboratory demonstrations and
field evaluations. This document summa-
rizes the results on the field demonstra-
tions and the cost estimates for each
alternative system. It should be noted that
the performance demonstrations were not
rigorous scientific investigations. Instead,
product evaluations are based on the print-
ers' experiences with and opinions of these
products as they were used in production
at their facilities.
Background
Most printers reclaim their used screens
instead of disposing of them due to the
high cost of the screen material and the
labor required to replace a screen. Screen
reclamation techniques vary from one fa-
cility to another; however, the three basic
steps performed to reclaim a screen are:
ink removal, emulsion removal, and haze
removal. Typically a different product is
used for each step, and in this project the
three products (ink remover, emulsion re-
mover, and haze remover) are referred to
as a "product system." For the DfE Perfor-
mance Demonstration Project, manufac-
turers were encouraged to submit complete
product systems to minimize the probabil-
ity of chemical incompatibilities among the
system components. A total of ten prod-
uct systems and one individual ink re-
mover were submitted.
Ink removal is the first step in reclaim-
ing a screen. In most facilities, an ink
remover product is sprayed, poured, or
wiped onto the screen. The ink remover
chemical and the ink are both wiped off or
rinsed off the screen with a water spray.
Next, the emulsion is removed. The pre-
dominant emulsion removal chemical in
use today is sodium metaperiodate. Typi-
cally, it is used in an aqueous solution
and is sprayed on the emulsion, rubbed in
with a brush and is rinsed off with a pres-
sure wash. After the emulsion is removed,
a haze from ink residue may remain on
the screen. A haze remover is typically
brushed onto the affected area then rinsed
off with pressurized water. Haze remover
chemicals are often caustics and can dam-
age or weaken the mesh if used exces-
sively or if allowed to remain in contact
with the mesh for too long.
Environmental Concerns
Associated with Screen
Reclamation
Screen reclamation was selected as the
focus area of this project for several rea-
sons:
• Screen reclamation products often
contain highly volatile organic
solvents. In order to meet regulatory
requirements and to protect the health
of the workers, many printers are
looking for less volatile cleaners.
• Wastewater from screen recla-
mation typically goes directly down
the drain. According to a 1992 Screen
Printing magazine survey, 76 percent
of companies reported they send
unfiltered waste down the drain. Ink,
emulsion, and/or reclamation
chemicals are likely to be in the
unfiltered rinse water which could lead
to health and environmental problems
as the water goes to a wastewater
treatment facility, or discharged to a
waterbody or septic system.
• Confusion over products that claim
to be "biodegradable," or "drain-
safe." Although a given product may
itself be safe to rinse down the drain,
once it is mixed with ink or emulsion,
drain disposal may not be permissible.
Also, confusion surrounding the term
"biodegradable" is widespread among
printers; each manufacturer, regulator,
and printer may define the term
differently.
Performance Demonstration
Methodology
Performance evaluations were con-
ducted in two distinct phases: (1) testing
at the Screen Printing Technical Founda-
tions (SPTF) under controlled and consis-
tent laboratory conditions, and (2)
demonstrations at volunteer screen print-
ing facilities under the variable conditions
of production runs. The testing methodol-
ogy for both phases of the demonstra-
tions was developed by consensus with
the involvement of EPA, SPAI, individual
screen printers, and manufacturers and
suppliers of screen reclamation products
and equipment. Due to the numerous vari-
ables associated with screen reclamation,
the work group agreed that a rigorous
scientific test of screen reclamation prod-
uct systems would be difficult to develop.
The group decided that it would be prefer-
able to rely on the seasoned judgment of
screen printers in evaluating the effective-
ness of the alternative products. Addition-
ally, the group felt that a month-long
demonstration at the volunteer facility was
required in order to identify the types of
problems that occur only after repeated
uses of the product on the same screen.
Manufacturers' cooperation in this
project was essential to gather perfor-
mance information on as many alternative
product systems as possible at the start
of the project. The DfE project staff con-
tacted all known manufacturers of screen
reclamation products designed for print-
ers who use vinyl or plastic substrates,
and invited them to submit alternative prod-
uct systems. To be considered an alterna-
tive, products were to contain no
stratospheric ozone-depleting substances
and no chlorinated compounds. Prior to
submitting their products, manufacturers
were informed that product trade names
would be masked throughout the demon-
strations. Neither the volunteer printers
nor the DfE observers knew the manufac-
turer of the products being evaluated.
Trade names are not reported out of this
project. Product systems are identified only
by a generic formulation: a list of the
chemical components associated with
each individual product.
In initial testing, each product system
was evaluated under laboratory conditions.
The intent of the laboratory evaluations
was to ensure that the product systems
sent to printers would provide an accept-
able level of performance. A description
of the results from the laboratory testing is
not included in this project summary; it
can be found in both the CTSA and the
full ORD report. In the second phase of
the project, volunteer printing facilities col-
lected performance information under vari-
able conditions specific to their production
runs. Each of the product systems was
evaluated in two or three facilities to pro-
vide performance data from different op-
erating and ambient conditions, and all
facilities were scheduled to use the alter-
native product systems for one month.
Results
Variability in Results
Performance demonstrations were not
scientifically rigorous but were subjective
assessments which reflected the condi-
tions and experiences of the reclamation
employees at two or three facilities. Table
-------
1 presents the results of product system
evaluations from each of the participating
facilities. Each system is referred to be a
Greek letter code name; actual product
trade names are not given. In several
cases, two facilities with the same operat-
ing parameters using the same reclama-
tion products had very different perceptions
of the product performance. Among the
reasons why the results of performance
demonstrations for one particular product
system may differ from one facility to an-
other are:
• Variability of screen conditions.
Because performance demonstrations
were carried out during production
runs, many factors which affect the
performance of reclamation products
were not controlled including: age of
screen, ink color, ink coverage, image
size, ink type and drying time prior to
reclamation.
• Variability of ambient conditions.
Conditions such as temperature,
humidity, and ventilation were
recorded but not controlled during
demonstrations.
• Chemical interactions with products
used previously on the screen.
Printers and manufacturers have
reported that chemicals previously
applied to clean a screen can affect
the performance of products currently
used to clean the screen.
• Variability of staff involved in
performance demonstrations. At the
facilities, several different individuals
often conducted the reclamations and
recorded the data. Reclaimers' past
experience also differs and can affect
their perception of performance.
• Level of cleanliness expected by
the facility. Different facilities often
have very different opinions about the
cleanliness of a screen. At some
facilities, a light haze is acceptable
and it does not affect the quality of
future prints. Other facilities may
require that every screen look new
after reclamation.
Costs
Costs were estimated for each recla-
mation system. The estimates included
the cost of: labor time spent to reclaim the
screen, the average quantity of reclama-
tion product used, the rags used, and the
hazardous waste disposal for RCRA-listed
chemicals. To compare the costs of the
substitute systems to a known system, a
baseline was established using a tradi-
tional solvent-based screen reclamation
system. The traditional system used in
the comparison consisted of lacquer thin-
ner as the ink remover, a sodium periodate
solution as the emulsion remover, and a
xylene/acetone/mineral spirits/cyclohex-
anone blend as the haze remover. These
chemicals were selected because screen
printers indicated they were commonly
used in screen reclamation. For all cost
estimates, it was assumed that the chemi-
cals were applied manually to 6 screens
per day, each 2,127 in2 (approximately 15
ft2) in size. Table 2 summarizes the cost
estimates of the alternative systems at
each demonstration facility.
Since product trade names are not
given, the printer must identify the prod-
ucts by their chemical class. Tables 3 and
4 provide printers with a list of the chemi-
cals used in each of the product systems
demonstrated. Table 3 lists the formula-
tion of each product system in generic
chemical categories. Table 4 describes
the chemicals which are included in each
generic category. Using the chemical com-
position information in conjunction with the
performance information in Table 1, print-
ers can determine which product system(s)
they think would be successful in their
facility. Once that determination is made,
printers can contact their distributors, in-
form them of the type of product they are
looking for (based on the chemical formu-
lation), and ask for a recommendation on
such a product system. A list of the par-
ticipating manufacturers is given in the
CTSA and in the full ORD report. For
information on the risks associated with
each product system, the printer should
refer to the CTSA Screen Reclamation
document.
Demonstration of Alternative
Technologies
In addition to the demonstration of al-
ternative chemical product systems, the
DfE Printing Project evaluated the perfor-
mance of two alternative screen reclama-
tion technologies: (1)a high pressure water
blaster; and (2) a sodium bicarbonate re-
claim system.
For the high (SOOOpsi) pressure water
blaster technology, an emulsion remover
and a haze remover were used, but no
ink remover was needed. The system was
demonstrated on three screens: one with
solvent-based ink, one with UV-curable
ink, and one with water-based ink. On all
three screens, the observer felt this tech-
nology efficiently and effectively cleaned
the screen, while reducing the labor, ef-
fort, and quantity of chemicals required
for reclamation.
The sodium bicarbonate technology con-
sists of an enclosed spray cabinet where
pressurized sodium bicarbonate (baking
soda) and water are sprayed onto the
parts inside the cabinet to clean them.
Prior this project, the sodium bicarbonate
technology was never tested for screen
reclamation applications. The advantage
of such a system for screen reclamation
is that no hazardous chemicals are used,
and the need for ink remover, emulsion
remover, and haze remover is eliminated.
In preliminary testing, the sodium bicar-
bonate technology showed potential for
removing solvent- or water-based inks.
Results on a screen with UV-curable ink,
however, were poor. In all cases, further
development and testing are needed be-
fore the technology could be used practi-
cally in a screen printing facility.
This report was submitted in partial ful-
fillment of Contract No. 68-D2-0175, Work
Assignment No. 2-21 under the sponsor-
ship of the U.S. Environmental Protection
Agency and it covers a period from De-
cember 16, 1993 to September 30, 1993.
-------
Table 1. Product System Performance at Volunteer Printing Facilities.
Ink Remover Performance
Emulsion Remover Performance
Haze Remover Performance
Overall System Performance
PRODUCT SYSTEM ALPHA
Variable results: removed ink
on most screens, but soaking
time or extra application
were needed.
INK REMOVER BETA
Removed ink, but required
extra time and left an
oily reside.
PRODUCT SYSTEM CHI
Removed ink with some extra
time and effort, but worked
very well with metallic inks.
Variable results: removed
stencil quickly and easily at
one facility, but required a lot
of scrubbing effort at another.
Not applicable; this man-
ufacturer submitted an ink
remover product only.
Removed stencil easily and
completely.
Variable results: Removed haze
on most, but not all screens at
one facility and worked well at
another.
Not applicable; this manufacturer
submitted an ink remover pro-
duct only.
Lightened, but did not remove
haze at one facility; haze
remover was not needed at
the second facility.
All 3 facilites using this system
found that some of their
screens had to be cleaned with
their standard product before
they could be reused.
This product was not demon
strafed as part of a system.
All screens could be reused for
future print jobs. At the one
facility where haze remover
was needed, printer was
concerned with the effect of
possible haze build up over
time.
PRODUCT SYSTEM DELTA
Removed ink well on most
screens, but left a residue on
some.
PRODUCT SYSTEM EPSILON
Removed the very well, but
one of the facilities found
several applications were
needed on some screens.
Removed stencil easily and
completely.
Removed stencil easily
and completely.
One facility did not need
haze remover. Did not re-
move the haze at the
other facility.
Removed haze, but some-
times a light ink stain
remained.
Good performance, except one
facility found the haze remover
did not work.
Good performance; all screens
could be reused for future print
jobs.
PRODUCT SYSTEM GAMMA
Ink residue and oily film
remained in mesh after
applying ink remover several
times.
PRODUCT SYSTEM MU
Variable results: Removed
ink well with less effort and
product needed than with
their standard product at
one facility; left ink residue
at the other facility.
Removed stencil completely
and easily.
Removed stencil completely
and easily
Did not remove the haze.
Variable results: Worked well
on moderate haze, but required
at least 1 hr wait time at one
facility; left ghost image in
screen at other facility.
The facilities discontinued use
of the ink and haze removers
after 1 - 2 weeks of demonstra-
tions due to poor performance.
Good performance at one
facility: all screens could be
reused for future print jobs; Fair
performance at the other
facility: their standard haze
remover was applied before the
screens could be reused.
PRODUCT SYSTEM OMICRON-AE
Ink residue remained in
the mesh.
PRODUCT SYSTEM OMICRON-AF
Removed the ink well.
Removed stencil completely
and easily.
Removed stencil completely
and easily.
Lightened the ink stain, but
did not remove it.
Reduced the ink residue, but
did not remove haze from screen.
Demonstration discontinued at
both facilities due to poor
performance.
Good performance for the ink
and emulsion removers, but the
facilities found the haze
remover did not work well.
PRODUCT SYSTEM PHI
Worked well on metallic inks,
but left an ink residue with
other ink types.
PRODUCT SYSTEM ZETA
Removed the ink if applied
several times, but usually
left a residue.
Removed stencil completely
and easily.
Worked well at times, but
results were inconsistent
and other screens required
a lot of scrubbing effort.
Did not consistently remove
the haze.
Seemed to have no effect
on haze.
A light stain remained on the
screen after reclamation, so the
screens could not be reused for
all types of printing jobs.
The three demonstration
facilities discontinued use after
a few days due to poor
performance.
-------
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-------
Table 3. Chemical Composition of Alternative Screen Reclamation Systems
Product System
Ink Remover
Emulsion Remover
Haze Remover
Alpha
Aromatic solvent naphtha
Propylene glycol series ethers
Sodium periodate
Water
Alkali/caustic
Tetrahydrofurfuryl alcohol
Water
Beta
2-octadecanamine, N,N-dimethyl-,
N-oxide or a modified amine from
unsaturated soy bean oil fatty acid
Water
Ink remover only
Ink remover only
Chi
Delta
Epsilon
Gamma
Mu
Phi
Diethylene glycol series ethers
Propylene glycol series ethers
N-methyl pyrrolidone
Ethoxylated nonylphenol
Dibasic esters
Propylene glycol series ethers
Ethoxylated nonylphenol
Cyclohexanone
Methoxypropanol acetate
Diethylene glycol
Benzyl alcohol
Diacetone alcohol
Aromatic solvent naphtha
Derivatized plant oil
Tripropylene glycol methyl ether
Diethylene glycol butyl ether acetate
Dibasic esters
Fatty alcohol ethers
Derivatized plant oil
Dibasic esters
Methoxypropanol acetate
d-Limonene
Ethoxylated nonylphenol
Derivatized plant oil
Dibasic esters
Sodium periodate
Water
Sodium periodate
Water
Sodium periodate
Sulfate salt
Water
Sodium periodate
Sulfate salt
Phosphate salt
Other
Water
Periodic acid
Water
Sodium periodate
Water
Ethoxylated nonylphenol
Other
Diethylene glycol series ethers
Propylene glycol series ethers
N-methyl pyrrolidone
Ethoxylated nonylphenol
Dibasic esters
Propylene glycol series ethers
Ethoxylated nonylphenol
Alkyl benzene sulfonates
Ethoxylated nonylphenol
Phosphate salt
Sodium hydroxide
Derivatized plant oil
Water
Sodium hypochlorite
Alkali/caustic
Sodium a Iky I su If on ate
Water
Sodium hypochlorite
Alkali/caustic
Sodium alky I su If on ate
Water
N-methyl pyrrolidone
Dibasic esters
Omicron
(AE)
Diethylene glycol butyl ether
Propylene glycol
Sodium periodate
Ethoxylated nonylphenol
Water
Ethoxylated nonylphenol
Phosphate surfactant
Other
Water
Omicron
(AF)
Diethylene glycol butyl ether
Propylene glycol
Sodium periodate
Ethoxylated nonylphenol
Water
Ethoxylated nonylphenol
Phosphate surfactant
Alkali/caustic
Other
Water
Theta
Zeta
None
Propylene glycol series ethers
Sodium periodate
Water
Sodium periodate
Water
Alkali/caustic
Cyclohexanone
Furfuryl alcohol
Alkali/caustic
Propylene glycol
Water
-------
Table 4. Categorization Of Screen Reclamation Chemicals For Use In Alternative Product System Formulations
Category
Chemicals in Category
Alkali/caustic
Alkyl benzyl sulfonates
Aromatic solvent naphtha
Derivatized plant oil
Dibasic esters
Diethylene glycol series ethers
Fatty alcohol ethers
Phosphate salt
Propylene glycol series ethers
Sodium hydroxide, Potassium hydroxide
Dodecyl benzene sulfonic acid, triethanol amine salt
Sodium salt, dodecyl benzene sulfonic acid
Solvent naphtha (petroleum), light aromatic
Solvent naphtha (petroleum), heavy aromatic
Tall oil, special, Ethoxylated castor oil
Diethyl adipate, Diethyl glutarate, Diisopropyl adipate
Dimethyl adipate, Dimethyl glutarate, Dimethyl succinate
Diethylene glycol butyl ether
Diethylene glycol butyl ether acetate
Alcohols, C8 - C10, ethoxylated, Alcohols, C12 - C14, ethoxylated
Sodium hexametaphosphate, Trisodium phosphate
Dipropylene glycol methyl ether, Propylene glycol methyl ether
Tripropylene glycol methyl ether,
Propylene glycol methyl ether acetate
Dipropylene glycol methyl ether acetate, Ethoxypropanol
Ethoxypropyl acetate, Methoxypropanol acetate
-------
Cheryl Keeman is with Abt Associates Inc., Cambridge, MA 02138-1168
Paul Randall is the EPA Project Officer (see below).
The complete report, entitled "Performance Demonstrations of Alternative
Screen Reclamation Products for Screen Printing," (Order No. PBX95-
230983; Cost $27.00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
National Risk Management Research Laboratory
U. S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-95/081
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