Bulletin 4 - Smarter, Safer Screen Reclamation - Alternative System
| The chemicals used for screen reclamation
can be some of the most hazardous products in a screen printing facility.
Highly volatile solvents are typically used. These cleaners may contain
chemicals that are harmful to the health of employees if inhaled,
i ngested, or absorbed through the skin. If they are not disposed
of properly, these products may also harm to the environment.
To reduce the hazards of screen reclamation to workers and to the environment, screen printers using solvents for screen reclamation should consider switching to one of the safer substitute products currently on the market. These substitutes often contain less harmful chemicals and have a lower volatile organic compound (VOC) content. With a lower VOC content, the chemical is less likely to be inhaled by employees or released to the air.
This bulletin highlights the characteristics of one type of substitute product system and compares it to a traditional (solvent-based) screen reclamation system. Specifically, this bulletin describes:
To access a table that summarizes the differences between the traditional and the alternative systems described in this bulletin, follow the links to the table found under each of the section headings.
| Initiated by industry, this project was entirely voluntary
and involved almost all sectors of the screen printing industry: manufacturers
donated their products for evaluation, staff from Screenprinting and
Graphic Imaging Association International (SGIA) coordinated the field
demonstrations, the Screen Printing Technical Foundation (SPTF) performed
initial product testing, printers nationwide evaluated the products
in their facilities, and EPA staff conducted a risk assessment of
the products. One advant age of this coordinated effort is that all
product systems were evaluated using the same methods. The consistency
of the evaluations allows you to compare the results to determine
which of the alternatives may be a viable substitute for your current
recla mation products.
This bulletin highlights one alternative system, referred to as Alternative System "Chi." This system, as with all systems demonstrated in this project, is a real, commercially available screen reclamation system; however, "Chi" is a masked name. The actu al trade name for this alternative system (or for any of the alternative systems demonstrated) is not used in this bulletin or in the final project report. Trade names were masked for several reasons:
To compare the cost and risk of Alternative System Chi to a known system, a baseline was established using a traditional solvent-based screen reclamation system consisting of: lacquer thinner as the ink remover, a sodium periodate solution as the em ulsion 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. It should be noted that these technologies were ev aluated using a case study approach; rigorous scientific testing was not conducted. Instead, much of the information presented here is based on printers' experiences with these products as used at their facilities.
| Performance was evaluated in two phases: 1) performance
demonstrations at SPTF's laboratory under controlled conditions; and
2) field demonstrations at volunteer printers' facilities under the
variable conditions of production. Since conditions vary great ly,
printers felt it would be most valuable to evaluate performance based
on the experiences and opinions of the experts: the printers who used
the alternative products in their facilities during month-long demonstrations.
Each product system was demonstr ated in two or three facilities to
get a more complete evaluation of performance under a variety of operating
| During laboratory testing, three imaged screens were
reclaimed using Alternative System Chi: one where a solvent-based
ink was applied, the second with an ultraviolet-curable (UV) ink,
and the third with a water-based ink. In the lab, two applications
of the Chi ink remover were required to remove the solvent-based ink.
The UV-curable ink and water-based inks dissolved more easily, however
an ink residue or haze remained on all of the screens after applying
the ink remover. The emulsion remover easily dis solved the stencil
with only light scrubbing, leaving no emulsion residue behind. When
additional ink remover was applied (used instead of a haze remover),
it removed the ink residue and lightened the stain on all three screens.
| Two different facilities (referred to as Facility C
and Facility D) used System Chi for a month to evaluate how well it
performed in an actual production situation. The participating facilities
recorded the amount of product used, the length of time neede d, and
their opinion of how well the product reclaimed the screen.
Ink Remover Performance:At Facility C, the Chi ink remover worked well, although in some cases, it acted more slowly than their standard solvent blend. Facility D found the ink remover worked well, especially on metallic inks.
Emulsion Remover Performance: The emulsion remover worked very well at both facilities, dissolving the stencil quickly and easily.
Haze Remover Performance: Alternative System Chi did not include a separate haze remover; instead the manufacturer recommended applying the ink remover again to remove any remaining haze. Facility D found their screens were completely clean after using just the ink and emulsion removers; a haze remover was not needed. At Facility C, the haze remover lightened the haze; however, when the haze was heavy, a ghost image remained on the screen.
Overall Evaluation: At both facilities, the performance of Alternative System Chi was as good as the performance of the facilitiesÕ standard screen reclamation products. The consistent performance of the product at SPTF and in the two facili ties demonstrates that System Chi can work under different operating conditions.
| Occupational risks and environmental releases associated
with using Alternative System Chi and the traditional system for screen
reclamation are summarized in the table.
Whether using traditional screen reclamation techniques or an alternative system, chemicals can get into your body either through your skin when you contact the product or through your lungs when you inhale chemical vapors. Some chemicals have a lower ten dency to evaporate or to enter the body through the skin; and different chemicals have different effects, some more harmful than others, once in your body. The risks associated with inhalation of the chemicals in Alternative System Chi were found to be ne gligible, while there is a clear concern for chemical inhalation risk with the traditional system. With the traditional system, daily inhalation of toluene and methyl ethyl ketone in the ink remover, and acetone in the haze remover could lead to eye, nose , and throat irritation, headaches, or fatigue. With Alternative System Chi, the adverse effects from inhalation are negligible.
Applying either the Alternative System Chi or the traditional system products regularly without wearing gloves can be harmful to your health. In the traditional system, these effects are from the toluene and methyl ethyl ketone in the ink remover, the sod ium periodate in the emulsion remover, and the acetone in the haze remover. In the alternative system, potential for these harmful effects through skin contact are attributed to diethylene glycol series ethers in the ink/haze remover, and sodium periodate in the emulsion remover. If gloves and safety goggles are worn regularly, however, the dermal risks from either system are negligible.
Minimal Environmental Releases
|Based on the EPA assessment, none of the chemicals in
either the traditional system or Alternative System Chi were found
to be hazardous to the environment in the quantities used for screen
reclamation. However, reducing the use of the traditional che micals
could cut a facility's air releases.
Traditional screen-cleaning solvents often have a high volitile organic compound (VOC) content, contain Hazardous Air Pollutants regulated under the Clean Air Act, or contain a RCRA listed or characteristic waste. Substituting an alternative product for t hese screen reclamation chemicals could reduce your facility's regulatory burden. Contact your state and local regulatory authorities for information specific to your location.
| The performance demonstrations showed that both of
the participating facilities could reduce their costs for screen reclamation
by switching from the traditional system to Alternative System Chi.
As with the risk comparisons, costs of Alternative System C hi were
compared to the costs of using the traditional system. It was assumed
6 screens were reclaimed daily and that all screens were 2,127 in2
(approximately 15 ft2) in size for both the traditional
and the alternative systems. The cost estimate for each reclamation
system included labor time spent to reclaim the screen, the cost of
an average quantity of reclamation products, and the cost of hazardous
waste disposal for RCRA-listed waste or RCRA-characteristic waste
(ignitable bas ed on flashpoint). For the alternative system and the
traditional system, RCRA issues apply only to the traditional system
For Facility C, their reclamation cost per screen would drop by 38% from $6.27/screen to $3.89/screen for annual savings of $3,560. At Facility D, the reclamation cost of $6.27/screen using the traditional system would decrease 48% to $3.25/screen at Faci lity D for the alternative system. Over a year, the savings would amount to $4,520. The difference in costs between the facilities is due to differences in the quantity of product used and the labor time required per screen as recorded by each facility's employees.
For More Information...
| Although the alternative system described in this case
study proved to be a viable alternative in the two printing facilities
where performance demonstrations were conducted, it may not be the
solution for all types of screen printing operations. If you f ind
that Alternative System Chi does not seem like a feasible substitute
for your facility, refer to the summary booklet, Designing Solutions
for Screen Printers: An Evaluation of Screen Reclamation Systems,
which includes information on all the al ternative product systems
and alternative technologies evaluated. When you identify a product
system that seems like a potential substitute, contact your supplier,
identify the alternative system by its chemical composition, and discuss
the characteristic s of the products you are looking for.
This bulletin is part of a series of bulletins and case studies that provide screen printers with information on products and techniques that can help them to prevent pollution in their facilities. Information in these bulletins is largely based on the wo rk done by the Design for the Environment Screen Printing Partnership. For copies of this bulletin, other DfE Screen Printing Partnership Materials, or mroe information about the project, contact:
Pollution Prevention Information Clearinghouse
Screenprinting and Graphic Imaging