EPA Project Summary

United States

Environmental Protection

Agency

Performance Demonstrations of

Alternative Screen Reclamation

Products for Screen Printing

Cheryl Keeman, and Paul Randall

National Risk Management

Research Laboratory

Cincinnati, OH 45268

Research and Development

Environmentally preferable products

for the screen reclamation process in

screen printing were evaluated by printers 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 alternative screen reclamation products were

demonstrated. Manufacturers submitted ten “product systems” for evaluation. Each product system included the

three chemical products commonly

used to reclaim a screen: an ink remover, a stencil or emulsion remover,

and a haze remover. Additionally, one

ink remover and two substitute technologies were demonstrated.

Performance of the alternative chemical systems was evaluated in two

phases: (1) laboratory testing to ensure the products were generally effective, 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 products. In general, most emulsion removers 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 facilities would realize reduced screen reclamation costs if switched from the

baseline to an alternative product system. The other 9 facilities would experience increased costs.

This Project Summary was developed

by EPA's National Risk Management

Research Laboratory, Cincinnati, OH,

to announce key findings of the research project that is fully documented

in a separate report of the same title

(see Project Report ordering information at back).

Introduction

The objective of the Screen Printing

Performance Demonstrations was to provide critical information on the performance

of environmentally safer screen reclamation products and technologies for the Design 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, environmentally sound decisions about the

chemicals and processes they use. This

non-regulatory, voluntary project is a cooperative partnership between the EPA,

the Screen Printing Association International (SPAI), printers, and manufacturers

of printing supplies. As one of the initial

tasks for this project, industry representatives selected screen reclamation as the

focus area for the DfE project.

In support of the EPA Office of Research and Development (ORD), the DfE

staff within the Office of Pollution Prevention and Toxics (OPPT) conducted the

EPA/000/SR-95/081 June 1995
2

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 Technologies 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 during demonstrations carried out between

January and April 1994 and include information such as time spent on screen reclamation, volume of product used, and

appearance of the screen after reclamation. Performance data came from two

sources: laboratory demonstrations and

field evaluations. This document summarizes the results on the field demonstrations 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 printers’ 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 facility 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 remover, and haze remover) are referred to

as a “product system.” For the DfE Performance Demonstration Project, manufacturers were encouraged to submit complete

product systems to minimize the probability of chemical incompatibilities among the

system components. A total of ten product systems and one individual ink remover were submitted.

Ink removal is the first step in reclaiming 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 predominant emulsion removal chemical in

use today is sodium metaperiodate. Typically, it is used in an aqueous solution

and is sprayed on the emulsion, rubbed in

with a brush and is rinsed off with a pressure 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 damage or weaken the mesh if used excessively 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 reasons:

• 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 reclamation 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 “drainsafe.” 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 conducted in two distinct phases: (1) testing

at the Screen Printing Technical Foundations (SPTF) under controlled and consistent laboratory conditions, and (2)

demonstrations at volunteer screen printing facilities under the variable conditions

of production runs. The testing methodology for both phases of the demonstrations 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 variables associated with screen reclamation,

the work group agreed that a rigorous

scientific test of screen reclamation product systems would be difficult to develop.

The group decided that it would be preferable to rely on the seasoned judgment of

screen printers in evaluating the effectiveness of the alternative products. Additionally, 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 performance information on as many alternative

product systems as possible at the start

of the project. The DfE project staff contacted all known manufacturers of screen

reclamation products designed for printers who use vinyl or plastic substrates,

and invited them to submit alternative product systems. To be considered an alternative, 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 demonstrations. Neither the volunteer printers

nor the DfE observers knew the manufacturer 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 acceptable 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 collected performance information under variable conditions specific to their production

runs. Each of the product systems was

evaluated in two or three facilities to provide performance data from different operating and ambient conditions, and all

facilities were scheduled to use the alternative product systems for one month.

Results

Variability in Results

Performance demonstrations were not

scientifically rigorous but were subjective

assessments which reflected the conditions and experiences of the reclamation

employees at two or three facilities. Table
3

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 operating parameters using the same reclamation 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 another 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 reclamation system. The estimates included

the cost of: labor time spent to reclaim the

screen, the average quantity of reclamation 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 traditional solvent-based screen reclamation

system. The traditional system used in

the comparison consisted of lacquer thinner as the ink remover, a sodium periodate

solution as the emulsion remover, and a

xylene/acetone/mineral spirits/cyclohexanone 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 chemicals 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 products by their chemical class. Tables 3 and

4 provide printers with a list of the chemicals used in each of the product systems

demonstrated. Table 3 lists the formulation of each product system in generic

chemical categories. Table 4 describes

the chemicals which are included in each

generic category. Using the chemical composition information in conjunction with the

performance information in Table 1, printers can determine which product system(s)

they think would be successful in their

facility. Once that determination is made,

printers can contact their distributors, inform them of the type of product they are

looking for (based on the chemical formulation), and ask for a recommendation on

such a product system. A list of the participating 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 alternative chemical product systems, the

DfE Printing Project evaluated the performance of two alternative screen reclamation technologies: (1) a high pressure water

blaster; and (2) a sodium bicarbonate reclaim system.

For the high (3000psi) 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 technology efficiently and effectively cleaned

the screen, while reducing the labor, effort, and quantity of chemicals required

for reclamation.

The sodium bicarbonate technology consists 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 bicarbonate 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 before the technology could be used practically in a screen printing facility.

This report was submitted in partial fulfillment of Contract No. 68-D2-0175, Work

Assignment No. 2-21 under the sponsorship of the U.S. Environmental Protection

Agency and it covers a period from December 16, 1993 to September 30, 1993.
4

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 Variable results: removed Variable results: Removed haze All 3 facilites using this system

on most screens, but soaking stencil quickly and easily at on most, but not all screens at found that some of their

time or extra application one facility, but required a lot one facility and worked well at screens had to be cleaned with

were needed. of scrubbing effort at another. another. their standard product before

they could be reused.

INK REMOVER BETA

Removed ink, but required Not applicable; this man- Not applicable; this manufacturer This product was not demon

extra time and left an ufacturer submitted an ink submitted an ink remover pro- strated as part of a system.

oily reside. remover product only. duct only.

PRODUCT SYSTEM CHI

Removed ink with some extra Removed stencil easily and Lightened, but did not remove All screens could be reused for

time and effort, but worked completely. haze at one facility; haze future print jobs. At the one

very well with metallic inks. remover was not needed at facility where haze remover

the second facility. was needed, printer was

concerned with the effect of

possible haze build up over

time.

PRODUCT SYSTEM DELTA

Removed ink well on most Removed stencil easily and One facility did not need Good performance, except one

screens, but left a residue on completely. haze remover. Did not re- facility found the haze remover

some. move the haze at the did not work.

other facility.

PRODUCT SYSTEM EPSILON

Removed the very well, but Removed stencil easily Removed haze, but some- Good performance; all screens

one of the facilities found and completely. times a light ink stain could be reused for future print

several applications were remained. jobs.

needed on some screens.

PRODUCT SYSTEM GAMMA

Ink residue and oily film Removed stencil completely Did not remove the haze. The facilities discontinued use

remained in mesh after and easily. of the ink and haze removers

applying ink remover several after 1 - 2 weeks of demonstratimes. tions due to poor performance.

PRODUCT SYSTEM MU

Variable results: Removed Removed stencil completely Variable results: Worked well Good performance at one

ink well with less effort and and easily on moderate haze, but required facility: all screens could be

product needed than with at least 1 hr wait time at one reused for future print jobs; Fair

their standard product at facility; left ghost image in performance at the other

one facility; left ink residue screen at other facility. facility: their standard haze

at the other facility. remover was applied before the

screens could be reused.

PRODUCT SYSTEM OMICRON-AE

Ink residue remained in Removed stencil completely Lightened the ink stain, but Demonstration discontinued at

the mesh. and easily. did not remove it. both facilities due to poor

performance.

PRODUCT SYSTEM OMICRON-AF

Removed the ink well. Removed stencil completely Reduced the ink residue, but Good performance for the ink

and easily. did not remove haze from screen. and emulsion removers, but the

facilities found the haze

remover did not work well.

PRODUCT SYSTEM PHI

Worked well on metallic inks, Removed stencil completely Did not consistently remove A light stain remained on the

but left an ink residue with and easily. the haze. screen after reclamation, so the

other ink types. screens could not be reused for

all types of printing jobs.

PRODUCT SYSTEM ZETA

Removed the ink if applied Worked well at times, but Seemed to have no effect The three demonstration

several times, but usually results were inconsistent on haze. facilities discontinued use after

left a residue. and other screens required a few days due to poor

a lot of scrubbing effort. performance.
5
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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 Sodium periodate Alkali/caustic

Propylene glycol series ethers Water Tetrahydrofurfuryl alcohol

Water

Beta 2-octadecanamine, N,N-dimethyl-, Ink remover only Ink remover only

N-oxide or a modified amine from

unsaturated soy bean oil fatty acid

Water

Chi Diethylene glycol series ethers Sodium periodate Diethylene glycol series ethers

Propylene glycol series ethers Water Propylene glycol series ethers

N-methyl pyrrolidone N-methyl pyrrolidone

Ethoxylated nonylphenol Ethoxylated nonylphenol

Delta Dibasic esters Sodium periodate Dibasic esters

Propylene glycol series ethers Water Propylene glycol series ethers

Ethoxylated nonylphenol Ethoxylated nonylphenol

Epsilon Cyclohexanone Sodium periodate Alkyl benzene sulfonates

Methoxypropanol acetate Sulfate salt Ethoxylated nonylphenol

Diethylene glycol Water Phosphate salt

Benzyl alcohol Sodium hydroxide

Diacetone alcohol Derivatized plant oil

Aromatic solvent naphtha Water

Derivatized plant oil

Gamma Tripropylene glycol methyl ether Sodium periodate Sodium hypochlorite

Diethylene glycol butyl ether acetate Sulfate salt Alkali/caustic

Dibasic esters Phosphate salt Sodium alkyl sulfonate

Fatty alcohol ethers Other Water

Derivatized plant oil Water

Mu Dibasic esters Periodic acid Sodium hypochlorite

Methoxypropanol acetate Water Alkali/caustic

d-Limonene Sodium alkyl sulfonate

Ethoxylated nonylphenol Water

Derivatized plant oil

Phi Dibasic esters Sodium periodate N-methyl pyrrolidone

Water Dibasic esters

Ethoxylated nonylphenol

Other

Omicron Diethylene glycol butyl ether Sodium periodate Ethoxylated nonylphenol

(AE) Propylene glycol Ethoxylated nonylphenol Phosphate surfactant

Water Other

Water

Omicron Diethylene glycol butyl ether Sodium periodate Ethoxylated nonylphenol

(AF) Propylene glycol Ethoxylated nonylphenol Phosphate surfactant

Water Alkali/caustic

Other

Water

Theta None Sodium periodate Alkali/caustic

Water Cyclohexanone

Furfuryl alcohol

Zeta Propylene glycol series ethers Sodium periodate Alkali/caustic

Water Propylene glycol

Water
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Table 4. Categorization Of Screen Reclamation Chemicals For Use In Alternative Product System Formulations

Category Chemicals in Category

Alkali/caustic Sodium hydroxide, Potassium hydroxide

Alkyl benzyl sulfonates Dodecyl benzene sulfonic acid, triethanol amine salt

Sodium salt, dodecyl benzene sulfonic acid

Aromatic solvent naphtha Solvent naphtha (petroleum), light aromatic

Solvent naphtha (petroleum), heavy aromatic

Derivatized plant oil Tall oil, special, Ethoxylated castor oil

Dibasic esters Diethyl adipate, Diethyl glutarate, Diisopropyl adipate

Dimethyl adipate, Dimethyl glutarate, Dimethyl succinate

Diethylene glycol series ethers Diethylene glycol butyl ether

Diethylene glycol butyl ether acetate

Fatty alcohol ethers Alcohols, C8 - C10, ethoxylated, Alcohols, C12 - C14, ethoxylated

Phosphate salt Sodium hexametaphosphate, Trisodium phosphate

Propylene glycol series ethers 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
8

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

BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

United States

Environmental Protection Agency

Center for Environmental Research Information

Cincinnati, OH 45268

Official Business

Penalty for Private Use

$300

EPA/600/SR-95/081