Josh Wells is the instruction coordinator for Ryonet Corp. (asi/528500). He started screen printing at the age of 15 and currently teaches classes internally and to the public. Contact him at firstname.lastname@example.org.
I’ve had my hands in waterbase inks for two decades now, and let’s just say that ink technology has come a long way. Twenty years ago, waterbase inks had a bad reputation for drying in the screens quickly. A couple test prints in and you were racing the clock to not have the ink dry up in your screen. Emulsion, too, had its problems; not long after the ink hit the screen, you were looking for pinholes and breakdown in the emulsion.
These are just a couple things that were commonplace on the press 20 years ago but are no longer true. And yet, these lingering perceptions about waterbase inks remain. When it comes to waterbase, a lot of myths need to be dispelled. Here are five I still hear on a consistent basis:
1. Waterbase ink dries too quickly in the screen to use effectively. There are two factors that I would say make this straight up not true. The first is that ink technology has come a long way. There are additives in the ink that now give it a longer “open time,” which simply means that they don’t dry in the screen nearly as fast as they used to. The better the open time, the friendlier the ink is to use. Also, techniques have been developed to keep it wet. Flooding the image prevents the open mesh in the image from drying out, which manifests itself simply as blockage in the screen. In very dry climates, misting the ink with a water bottle every once in a while as you print also keeps the ink from drying out.
“Drying waterbase inks needs to be thought of as a ‘slow and low’ kind of process – lower temp and longer time.”
2. It’s hard to make the screens last through an entire run. Water-resistant emulsions are much more prevalent, easy to use and accessible than they used to be. Screen printers would, at one time, shy away from these hard-to-reclaim emulsions. Now they are easier to reclaim and work very well on press. Plus, they don’t typically cost much more. There are also a couple other techniques that can bolster the strength of any screen (especially waterbase). First is post exposure. Post exposure is easy to do. Once the screen has been exposed and dried, return the screen to the exposure unit to further the hardening of the emulsion. You can also do this in the sun – that is, if you don’t live in the Northwest. Next, use an emulsion hardener. Once you have exposed the screen, you simply apply the emulsion-hardening chemical to both sides of the screen and let it dry. Read the directions though, since some emulsion hardeners are recommended to dry for hours before use. Finally, use water-resistant blockouts to cover your targets and file info, which will prevent waterbase inks from leaking out of these little spaces. Using techniques like these mean that your screens aren’t breaking down any time soon.
3. You can’t mix to PMS colors accurately. I find there still are a couple of systems out there that make colors come out pastel. However, mixing systems, with all their software and components, make mixing relatively easy and consistent. (Obviously, there’s still a human element here when it comes to measuring and weighing properly.) A couple side notes: First, waterbase inks are by nature less opaque and are going to be affected by the color of the garment. Secondly, keep in mind that due to the flat nature of the finish of the ink, you should mix to the Uncoated Pantone Guide.
4. It can only print on cotton. Waterbase ink is now appropriate for a wide range of garments. The ink, of course, can go on natural fibers such as cotton, hemp or bamboo, but can also go on blends and even on 100% poly. When going on poly, you must use a low-cure additive like Green Galaxy’s “Warp Drive.” I’ve found it doesn’t always like to go on rayon or blends with rayon – the ink will often fade in the wash when the garment has rayon in it. But only with rayon, which brings me to my last myth ...
5. Waterbase ink fades in the wash. When anyone tells me this is the reason they don’t use waterbase ink, my first question is, “How long did you cure the ink, and at what temp?” When you cure waterbase ink, you are not only curing ink, but also evaporating out the moisture in the ink. It therefore takes much longer than plastisol – same temperature, but longer time. In order to avoid this, I see a lot of printers do the opposite – crank up the heat and speed up their times for more production. Drying waterbase ink needs to be thought of as a “slow and low” kind of process – lower temp and longer time. Not everyone has a nice long conveyor dryer to make this magic happen. Some have smaller conveyors or maybe no conveyor at all. For those of you in this situation, I would look into using a low-cure additive.