Sustainability in the Screen Printing World? It’s Complicated.
When it comes to sustainability claims in the fashion industry, it pays to look behind the curtain.
Global apparel is a trillion dollar industry that keeps us all clothed, but the process casts a large footprint on our environment. The average person today buys 60 percent more clothing than they did 20 years ago, and they throw out more as a result. Less than one percent of used clothing today is recycled or reused. According to the World Bank, the fashion industry uses more than 93 billion cubic meters of water. That’s enough to meet the needs of five hundred million people. An estimated 20 percent of wastewater worldwide comes from fabric treatments. The fashion industry contributes 10 percent of annual global carbon emissions; that’s more than all international flights and maritime shipping combined. At its current rate, the fashion industry’s greenhouse gas emissions are expected to increase by more than 50 percent in the next 10 years.
These statistics are sobering and have brought needed attention and urgency to sustainability and environmental friendliness in the fashion industry. There’s a lot of opportunity for growth, particularly given the apparel industry’s size and scale of impact.
There has been a lot of positive and science-based progress made in recent years, but at the same time, we’ve seen an increase in bold and unsubstantiated claims suggesting that various apparel-related products are “greener” or “more eco-friendly” than others. Because these claims are largely unregulated, it should come as no surprise that many are unsupported by facts, are misleading, or flat out wrong. For example, organic cotton shirts may seem like the “greener” choice over polyester. Would it change your perception if you considered that it takes hundreds of gallons of water to grow, dye, and treat one shirt, and that many polyester shirts are now being spun from recycled plastic products?
Let’s take a closer look at the environmental impact of screen printing inks – the primary consumable for apparel decoration. As a supplier to the industry, we’re often asked why certain screen printing ink products (such as water-based inks) are represented as environmentally friendly and others (most notably PVC plastisols) aren’t. Is one truly friendlier to the environment or more sustainable than the other? Not necessarily. Certainly there are differences between PVC, acrysol, and water-based ink products, but they are all plastics. Yes, water-based inks, like plastisols and acrysols, are plastics.
Fact or Fiction?
PVC plastisols have been, and continue to be, the inks of choice in North America. They’re versatile, easy-to-use, cost-efficient, and safe. Plastisols don’t dry in the screen because they don’t cure until they’re heated. Plastisols are considered “100-percent solids” and consequently provide virtually a 100-percent yield. What you print on the garment stays on the garment. Most water-based inks contain 20 to 30 percent solids. The highest solid, water-based inks contain no more than 70 percent solids.
Printers looking for an alternative to PVC are generally looking to acrysol or water-based inks. Like plastisols, acrysols are made up of 100-percent solids and provide the same high yield. They’re easy to use, and print and behave like PVC plastisols. They don’t dry in the screen and most don’t require a flash after every print.
There’s a misguided notion that water-based inks consist of water and pigments. That is incorrect. All water-based inks contain a plastic binder (usually an acrylic or urethane) and various additives (pigments, fillers, retarders) that are suspended in water and other co-solvents. In fact, many high-solids, water-based inks contain relatively little water. Water-based inks aren’t as popular as plastisols in North America, largely because they’re not as easy to use (drying in the screen), not as efficient (lower yields, daily cleaning, more waste), require more energy and time to cure, and in the case of some “high-solids” inks, are more expensive.
Claims that water-based inks are more environmentally friendly than plastisols and acrysols are questionable at best. All three inks rely on plastic resins or binders, pigments, fillers, and various chemical additives. Plastisols and acrysols contain plasticizers that cross-link with the plastic resin. These plasticizers don’t evaporate off, but become part of the ink film. Water-based inks, on the other hand, rely on solvents that evaporate, leaving the pigmented binder compounds on the garments. These evaporative solvents may represent more than 70-percent of the ink. While the primary solvent is water, water-based inks often contain co-solvents such as alcohols, glycols, and formaldehyde. These co-solvents may be harmful and put printers at risk unless they are properly protected from the evaporative fumes.
Plastisols, acrysols, and water-based inks have environmental footprints that are quite different. Water-based printing generally requires more energy to power more flashes and cure/ventilate (to drive off the moisture) and more water (primarily for daily cleaning). At the end of a print day, plastisol and acrysol can be left on the screen or put back in the bucket for use at another time. This is not necessarily so with water-based inks. Water-based printing consumes more water and generates more water waste. That waste, quite often, is accidentally poured down the drain.
The common misconception is that water-based inks are benign because they’re largely water. Not so. They’re chemical compounds that, aside from their harmful co-solvents, contain other chemicals (binders, fillers, additives, mold inhibitors, and pigments). Some of these chemicals are considered hazardous and must be managed as such. Plastisol and acrysol waste that can’t be reused can often be recycled for other uses or, when cured, can be disposed as a regular plastic. Water-based binders in some cases may be disposed similarly if all solvents have evaporated.
The point here: take the time to learn which inks work best for your situation. I’m not suggesting plastisols and acrysols are better than water-based inks. But at the same time, water-based inks aren’t necessarily better or greener than plastisol or acrysol inks. Remember that, in the end, how you manage your shop – materials, energy, workflow, reuse/recycle, and waste – will largely determine how “green” your operation is.
The next time you hear a claim about one product being green or greener than the next, take the time to understand the basis of that assertion. Someone may be attempting to “greenwash” their products.
Steve Kahane is International Coatings’ president and CEO. Prior to joining International Coatings, he held senior executive positions in the environment and engineering fields, and served on the faculty of the UCLA School of Public Health where he taught a core course on environmental health.