Water based screen printing applications
There are two major schools of screen printing ink; plastisol and water based. Plastisol is a PVC based ink and is what the majority of commercial printers use. Water based is, as the name suggests, a water based ink with pigments suspended within it.
Water based inks can be used to print stickers, towels, fabric yards, canvas and paper, as well as apparel such as shirts, sweatshirts, hoodies, jeans, aprons, jackets, hats and practically any other item as long as it can be put on the press to be screened. Designs can be printed on cotton, polyester, or poly/cotton blends.
Water based screen printing results
Water based prints have many positive qualities. The industry term "hand" refers to how soft a print feels on the decorated item. Water based inks are well known for the minimal or soft hand that they provide. Prints made with water based can be ironed, while plastisol prints cannot be, as the iron's heat plate would melt the PVC in the ink.
The colors in a water based print are often more vibrant than those in a similar plastisol print. When properly cured, a shirt or other item with a water based print will survive countless trips through the washing machine, being very durable, and the ink would most likely outlast the fabric on which it is printed. Because of the lesser hand of water based, a shirt with a very large and solid design printed on the front will feel light and thin, while sometimes large heavy plastisol printed designs are referred to as "bulletproof" because of the thickness of the layers of ink.
Water based ink sits into the fabric of the printed shirt, not on top of the fabric like plastisol printing. This allows skin under the design to breathe better, and can increase the amount of comfort felt while wearing the decorated item.
Water based screen printing and the environment
Even minimal research into the effects of plastic on the environment brings up lists of serious hazards and harmful consequences. Plastic is polluting our oceans, filling our trash dumps, and doing permanant damage to our world, our environment and our future here on Earth. Plastic has countless uses and is a great building and manufacturing material in and of itself, but cannot easily be reused. A plastic soda bottle put on the curb in a recycling bin can never be melted down to be used as another soda bottle.
Plastisol is PVC ink. PVC is polyvinyl chloride, and is a known carcinogen, meaning that it can cause cancer. Plastic's chemicals can leach out of products. As the Green movement furthers, more people will turn away from plastic in every realm possible, and this will, and already does, include their preferrence to what type of ink is used on all the screen printed goods that they purchase and wear.
Plastisol is not drain safe. Printers must use other harmful chemicals to break down the plastisol ink from their screens and equipment. Special filters must be installed on drains to catch the PVC particles. Most do take care to not allow any to go down the drain, but many do not.
Among commercial printers, plastisol is popular because it's simple, inexpensive, and well suited to mass production because the ink will not dry and clog screens. In fact, plastisol really can never dry, it stays in a semi-liquid state until a curing temperature is reached, at which point it bonds to make a solid film. To cure water based ink, the item is heated to the proper temperature at which the water in the ink is evaporated, leaving just the pigments.
Water based ink is definitely more environmentally friendly. After a run of prints, screens can be cleaned with just water, and it can go down the drain, being no more harmful than mild household cleaning products. Water based inks are simply not toxic, do not contain lead or any heavy metals, nor do they contain any ozone-depleting chemicals (CFC's, HCFC's, etc) or volatile solvents.
Water based screen printing and the future
Luckily, the Green movement is having a serious impact on consumers' choices. People are wearing organic clothing, buying hybrid cars, and eating non-GMO food products. Plastisol may be the default choice for most professional screen printers, but water based does have a foothold in the industry, and its popularity will continue to grow, due to increasing demand from the level of the consumer and enlightened persons in charge of clothing lines.
Another reason why water based inks aren't going to go away is because of the advancements being made in the industry. Companies such as Matsui and Permaset are making serious advances in ink technologies, giving their water based ink lines qualities that only plastisols had previously, such as stretchability and durability to not crack, even with multiple layers, when cured properly. As development continues, water based ink will continue to obtain plastisol qualities, while remaining the best choice for anyone environmentally concerned.