Screen printing, also called silk screening and serigraphy, is a fascinating and highly versatile printing technique that can be applied in many forms of arts and fashions. SilkScreeningSupplies.com has an excellent 10-minute overview video on silk screen / screen printing and a series of instructional how-to videos on screen printing. SilkScreeningSupplies.com, the Web sales engine for Ryonet Corporation, does sell some environmentally friendly soy-based cleanup products along with many not-so-environmentally-friendly inks and screen printing chemicals.
Unfortunately, conventional screen printing can be damaging to the environment, health of printers and wearers of silk screened fashions because of the toxicity of many of the chemical inks, cleaners, preparation products and waste products from the silk screening process.
Basically, there are two main categories of screen printing inks: plastisol and water-based. Each has their technical printing advantages and disadvantages. Water-based inks are less toxic with fewer health and environmental hazards, but they are more difficult to use and offer less creative freedom. Plastisol inks do not soak into the fibers of the cloth like a dye or water-based ink; they wrap around and coat the fibers with a mechanical bond rather and a chemical bond.
Plastisol inks, commonly used for textile printing and especially for tee shirts, are a thermoplastic PVC-based ink composed of a clear, thick plasticizer fluid and PVC resin. The full name for PVC is â€śpolyvinyl chlorideâ€ť. According to Union Inks, â€śPlastisol inks are innocuous when used with reasonable care. A true plastisol ink contains no air-polluting solvents or volatile organic compounds. The manufacture, transportation, storage, use, and disposal of plastisol inks do not cause injury, illness, or environmental contamination as long as the appropriate safety and environmental protection procedures are followed. Most plastisol inks have a Health Rating of 1 (hazard - slight), a Flammability Rating of 1 (hazard - slight), a Reactivity Rating of 0 (hazard - minimal) and a Personal Protection Rating of B (wear safety glasses and gloves).â€ť
The major health concern about plastisol inks is not that they are PVC-based but that they contain phthalates. Phthalates are added to PVC plastics to transform a hard plastic into a soft, rubbery plastic by allowing the long polyvinyl molecules to slide against each other instead of rigidly binding together. Phthalates are more ubiquitous than lobbyists in Washington, DC. About 800 million pounds of phthalates are produced each year globally and they are used everywhere in a wide array of products such as cosmetics, perfumes, paint pigments, hair sprays, wood finishes, plastics used in making medical devices, automotive interiors, toys, soft rubber handles of kitchen utensils and workshop tools, and many, many other products â€¦ including textile screen printing inks.
Medical research has linked high doses of phthalates to damage of the liver, kidneys, lungs and testes in rats. Another medical studyRecent research at the U.S. Environmental Protection Agency strongly suggest that low levels of in utero exposure in rats to some classes of phthalates cause abnormalities in reproductive system development of male rat newborns. And there are a host of other studies casting concern about the health consequences of different classes of phthalates. suggest that phthalates contributes to allergies in children.
Even California Governor Arnold Schwarzenegger has jumped on the issues of phthalate safety and health concerns when he signed legislation on 7 October 2007 banning phthalates in toys and other product intended for children 3 years old and younger. Arnold decreed that â€śThese chemicals threaten the health and safety of our children at critical stages of their development.â€ť
But, the phthalates industry has been pushing back hard and donâ€™t forget that phthalates are a huge global industry that touches countless products around the world. Phthalates.org presents a strong defense for the safety of phthalates. They cite that a number of studies have found some classes and dosage levels to be safe or failed to support health concerns. They state that â€śNo governmental review has found any phthalate unsafe as used in products for the general public.â€ť Depending upon how you parse that statement from Phthalates.org that might â€¦ or might not â€¦ be factual. Levels of exposure also affect results and phthalates are a large class of chemicals with varying affects on the human and animal physiologies.
Exposure to one product containing phthalates might not cause reproductive organ abnormalities, cancer or asthma in children but when a small exposure comes from hundreds of sources everyday then the effects are uncertain but probably accumulative. Multiple chemical sensitivities are the result of a thousand chemical straws gradually wearing down the bodyâ€™s natural immunities breaking the back of the bodyâ€™s resistance to environmental impurities. According to the Phthalates Ester Panel of the American Chemicals Council, the EPA under the Great Lakes Water Quality Initiative has classified phthalates as non-bioaccumulating meaning that the body will not retain phthalates in tissues or organs. We will leave it to you to review the literature to decide to what degree you wish to expose your body and health to phthalates.
If you wish not to invite phthalates into every nook and cranny of your life, you might want to exclude them from your clothing which comes into close, personal and extended contact with your absorptive skin. And one way to do this is by requiring that your printed and silk screened clothing be printed only with inks free of phthalates and PVC's such as those from Chopper Couture.
To meet the growing demand for healthier clothes, more and more textile ink manufactures and suppliers and commercial silk screen printing shops are offering garment inks free of phthalates.
One of the more interesting commercial screen printing companies is T.S. Designs and their REHANCE screen printing process which avoids using plastisol inks. TS Designs trumpets their new REHANCE printing process, which they developed in conjunction with Burlington Chemicals, as using a new technology of water-based chemistry for printing and dyeing fabric where the print chemically bonds with the cellulose fiber of the fabric. This bonding makes the screen printed fabric more breathable and softer to the touch. It also means that clothing printed with REHANCE can be ironed without worry of the plastisol inks melting.
In addition to having significant personal health and environmental safety benefits by being free of PVCâ€™s and phthalates, REHANCE also offers design and quality improvements. Another interesting feature of the REHANCE technology is that the design is printed on the fabric first and then the garment is dyed in whatever color the designer wishes. Conventional screen printing requires that the clothing be dyed first as that effects the types of inks that can be used in the screen printing. Designs printed with REHANCE will not flake or chip away after repeated use and washings like designs done with conventional screen printing using plastisol inks.
The Lancer Group International, a leading manufacturer and supplier of plastisol inks and screen printing equipment, is also greening their silk screening inks with their new EvolutionÂ® PVC Free Inks that print like conventional plastisol but do not contain PVC or phthalates. Instead, EvolutionÂ® PVC Free Inks are made with non-PVC resins and non-phthalate plasticizers.
Most non-PVC and non-phthalate inks are acrylic-based. An acrylic resin replaces the PVC resin in typical plastisol inks and the plasticizers used do not contain phthalates. Acrylic inks have many of the same favorable printing characteristics of plastisol inks but can be a little trickier to use in printing.
QuantumOne from Wilflex is another non-PVC and non-phthalate plastisol screen printing ink that has similar look, feel and characteristics of conventional plastisol screen printing systems.
The hazards of conventional textile printing inks are not just to personal health but also to environmental health. Garments coated with plastisol inks do not decompose and they are difficult to recycle. The result is that you may soon grow tired of your Rolling Stones concert tee shirt and trash it, but it will live on in immortality in the local landfill.
Screen printing is a messy business surrounded by solvents, cleaners, inks and other chemical compounds, many of which are environmentally hazardous, that are used heavily in the preparation, printing and cleanup. Regardless of the type of ink used, the waste waters from cleaning screens, squeegees, tools and the work area will contain pigments, binders, thickeners and solvents â€“ most of which are probably hazardous, non-biodegradable, and must be properly and environmentally disposed. Screen printing waste products can not just be dumped down the drain.
Michael Beckman has written an excellent article, â€śGreen Printing Uses Sustainable Methods and Materialsâ€ť, giving specific steps on how screen printers can improve the sustainability of the screen printing process. Michael Beckman, a highly innovative and respected authority on screen printing, is also the R&D manager in Portland, Oregon, of the European T-Shirt Factory, based in stanbul, Turkey.
The European T-Shirt Factory is an interesting green printing story with a strong â€¦ and sincere â€¦ sustainability focus supported by ethical workplace policies for their employees. For their large commercial clients like Nike, Adidas, Polo and Wal-Mart (of course), the European T-Shirt Factor does everything from the knitting of tee shirts using certified organic cotton on tubular knitting machines, to eco-friendly screen printing on the finest commercial screen print equipment, to packaging (including bar coding, tagging and bagging), to distribution directly to their retail stores. Besides screen printing, the European T-shirt Factory also does apparel embroidery in its Egyptian facility.
The environmental impact of screen printing is not just confined to the silk screening process and cleanup but also to the manufacturing of many of the chemicals used during the screen printing process. According to the textile printing experts at TS Designs, nasty dioxins are created during the production of PVCâ€™s. If clothing designed with PVC plastisol ink is incinerated, the trapped dioxins plus hydrochloric acid (a primary component of acid rain) are released into the atmosphere.
So what is the environmentally conscious consumer to do? If you have a Harley parked in your garage or have aspirations to cultivate a motorcycle biker chick mystique, check out the eco-fashions at Chopper Couture. If you are looking at screen printed clothing, ask the retailer if it is PVC-free and phthalate-free. Also ask if the textile was printed at a green eco-printing shop. Let retailers and manufacturers know that you are concerned about the environment and that you are an eco-conscious shopper.