Mastering Water-Based Inks
The time is ripe for printers to learn how to use these products properly.
Prior to the 1960s, water- and solvent-based inks were the first choice – the only choice, really – for apparel printers. In those days, the garment decoration business was certainly not what it is today in terms of sheer numbers. However, screen printers that did image T-shirts then struggled with a number of production issues: ink transparency, drying in the screen, emissions, stencil breakdown, curing, washfastness, storage, and more.
Then, in 1959, a gentleman named Don Pettry who worked for Flexible Products Company developed plastisol inks, changing garment printing forever. Plastisols used a PVC (polyvinyl chloride) resin and plasticizer to produce what is, in essence, liquid plastic. The inks were easy to cure, didn’t dry in the screen or attack the stencils, presented no shelf-life considerations, produced a durable ink film, and had a good level of opacity to boot. They also enabled small entrepreneurs to get into the business by greatly reducing the cost of drying equipment. The forced-air units with long tunnels required for water-based inks weren’t necessary; small electric dryers could cure this ink just fine. The development of plastisol ink was truly a game changer for our industry and a key factor in the rapid growth of printed apparel in the ‘70s and ‘80s.
Plastisol has been the king for a long time, but its fortunes have been reversing in recent years. Why is the industry moving back toward water-based inks? In my view, the two key reasons are brand requirements and fashion trends.
A number of major brands list PVC on their Restricted Substance Lists (RSLs), and more are following suit. Nike, by most accounts the top global apparel brand, began phasing out PVC as far back as 1998. Most of the other top apparel brands have some type of PVC restriction as well, including fast-fashion retailers Zara, H&M, and Uniqlo (brands that those of you with teenage daughters surely know). These merchants are rapidly gaining a much larger presence in the US with the downslide of the “Big A’s” – Abercrombie & Fitch, Aéropostale, and American Eagle – brands that teenage consumers have abandoned in recent years.
To understand why PVC is being restricted by so many brands and retailers, we must first understand what PVC is and where it is used. The fact is, PVC-based products are everywhere – in all aspects of our lives. PVC is the third-most widely produced polymer after polyethylene and polypropylene. It comes in two primary forms – rigid and flexible. Rigid PVC is used primarily in the construction industry for products such as vinyl siding and pipes. Flexible PVC is found in a host of things including insulation, inflatable products, patio furniture, banners, anti-fatigue mats, toys, and, yes, plastisol screen-printing inks.
So what, exactly, is the big deal about PVC? It really boils down to three issues. First, the vinyl chloride monomer that is used to create PVC pellets is a carcinogen in its raw material form. (Upon polymerization into the PVC resin, however, it is inert.) Second, certain types of plasticizers known as phthalates that are used to soften the PVC and make it pliable are known to be hormone disrupters. Most US plastisol manufacturers no longer use these chemicals, having switched to non-phthalate plasticizers. And lastly, improper incineration of PVC releases dioxins into the environment, which is the real crux of the matter.
Here is a trivia question: Who remembers the US government banning phthalate plasticizers in screen-printing inks under the Consumer Product Safety Improvement Act (CPSIA) in 2008? Do I see some hands going up in the back of the room? Well, the fact is that phthalates were only banned in children’s toys and child care articles (defined as items designed to facilitate the sleep or feeding of a child under the age of three), and of the many phthalates used commercially, only six were specifically listed. So do screen-printed apparel items fall under this legislation? If you are printing baby bibs or bed sheets, they certainly do. But what about a superhero design printed on a T-shirt marketed to a 10-year-old boy? I don’t think it meets the definition, but this type of product has been encompassed in the anti-phthalate effort.
To the best of my knowledge, there is not a single piece of legislation in the world banning PVC. So if legislation isn’t prompting its removal from printed apparel, what is? It’s happening because of brand and retailer initiatives, bans that have been prompted by social media campaigns and public pressure from consumers and organizations such as Greenpeace.
If you aren’t convinced that the market is moving away from PVC inks, consider this: In early 2014, my company, the Textile Ink Business Unit of Nazdar SourceOne, queried key suppliers of plastisol and water-based textile inks about sales trends in the North American market. While the numbers varied slightly, the trend slope we saw was remarkably consistent, with all the suppliers we interviewed predicting a significant drop in plastisol’s market share (currently about 70 percent of garment ink sales in the US today in our estimation) through 2018.
One of the strongest trends in textile screen printing today is the growth of athletic apparel – “athleisure,” as it is known. Though sports involvement is actually down, wearing athletic clothes has become fashionable due to comfort and style. According to the NPD Group, sales of general apparel (100-percent cotton and traditional poly/cotton blends) declined in the last 12-month reporting period while activewear exhibited significant growth over the past several years. Activewear sales have grown to $33.7 billion, representing 16 percent of the total apparel market.
The other important trend affecting ink selection is that special effects have come back in a big way since their decline after the 2008 recession, and will continue to be an integral part of many branded designs. Numerous special effects are available in water-based chemistries, including flock, foil, gels, reflective, glow in the dark, color change, puff, suede,
and cracking inks. Regarding cracking inks, one advantage water-based chemistry has over plastisol is the availability of a self-cracking formulation that doesn’t require the garment to be stretched after curing to get the desired effect as with plastisols and many water-based products; instead, the effect happens in the dryer as the ink film is cured. Below is a close-up of a print where a self-cracking ink was used for the underbase and top coat.
Reflective inks, in particular, seem to be making a comeback, especially for branded sportswear. A relatively new, exciting special-effect product available in water-based versions is a clear reflective ink, which can be overprinted on top of flash-cured colors to create multicolor reflective designs with the use of just one reflective ink screen.
Finally, consumers continue to demand softer garments, and thus softer prints. You cannot beat the softness of using traditional water-based inks for light goods and discharge and/or high-solids water-based inks for darks. For a few years now, there has been a trend among plastisol printers to use a discharge underbase instead of a white plastisol on dark, 100-percent cotton garments.
This enables them to overprint with soft-hand plastisols through finer mesh counts, yielding a significantly better hand than if the job had been done with plastisol alone.