Ryonet | #PoweringThePrint
Emulsion takes a special kind of beating when printing water based and discharge ink. Print after print, the edges of your stencil start to get soft and wavy. Your crisp prints soon become fuzzy. It’s a slow battle between the ink and the emulsion, and it occurs because of the high water content in both kinds of ink. Sound familiar? You’re not alone.
In the search to make a better screen, we’ve searched the minds of seasoned printers for the best techniques to help you to prepare a screen for water based printing in your next job.
Choosing The Right Mesh
One of the first steps to prepare a screen for water based printing is to choose the right mesh for your ink. Since water based inks are thinner than plastisol inks, you will need to choose a slightly higher mesh count to prevent the print from getting muddy.
“The lowest mesh I would ever go with when printing water based inks is 156. There are only a handful of occasions that I would ever want to go below a 156. Like, if I’m printing an underbase or printing on a poly-lycra blend I may venture into the 86 or 110 range. However, outside of those exceptions using screen mesh lower than 156 can actually deposit too much ink and cause oversaturation, which causes issues when curing the ink.” –TJ Stepper
Base your mesh count decision on your image detail and coverage area of your print. The larger the area and the less detail present in your design, the lower the mesh count. Between a 156 or 200 mesh. The higher the detail and smaller the coverage, the higher you can go in mesh count.
Preparing Your Screen
Don’t skip degreasing. Whether your screen is fresh out of the box, or you’ve reclaimed it more times than you can remember. The first step to a high-quality screen is a clean screen. Using a degreaser removes any oils, dust and dirt from the mesh, all of which can cause issues in the adhesion of your emulsion, such as pinholes and fish eyes. These issues are especially concerning when printing with water based inks, since the emulsion is prone to faster breakdown already. Starting with a properly degreased screen will help your stencil to last longer.
“Degreasing cleans the oils and chemicals off of the screen mesh, and will absolutely keep your stencil from breaking down over a print run. Everything in printing comes back to the quality of pre-press work, why skip this part?” –Pen and Screen Printing
Picking The Right Emulsion
When printing with water based inks, it’s important to choose a water-resistant emulsion to coat your screen. The truth is, all emulsion types are water soluble at some level. But some more so than others. Using a water resistant emulsion will help you to avoid premature emulsion breakdown, and, for those extra long runs, there are additional steps you can take to fortify your emulsion to help prevent this.
“We struggled for a long time against water-logging. Our emulsion edges would get wiggly and soft and we just couldn’t get our water based prints to look good after a few hundred shirts. Then we started using Green Galaxy CryoCoat, it’s an emulsion made specifically for water based printing, and we’re never going back.” –Screen Shop
Once your screen has been exposed, you have the option to take an additional step of hardening it. You can do this a couple of ways. One, you can put the screen back on the exposure unit and expose it again. This re-exposure process will help to harden any remaining soft emulsion. Do this after you have already washed out the image and your design is print-ready. Second, you can chemically harden it with products like Harden-X. To do this, spray the hardener onto the washed out and dried screen. Spread the hardener evenly over the emulsion and wipe the excess off with a rag. Then, let it dry. It will take time for the hardener and the emulsion to chemically bond. To get the best results, let it dry for at least 24 hours.
“Post-exposing the screen will help a lot with durability, and a hardener will help even more if the print run is long. We harden screens regardless for runs larger than about 1000 pieces.” –Pen and Screen Printing
Whether you use Harden-X or just simply post-expose with UV light, this step is important to create a screen that that will last longer. The downside is that both of these steps make it more difficult to wash out the stencil during the reclaiming process. Though it’s a small price to pay to prevent your screen from prematurely breaking down during the printing process.
Just dipping your toes into the realm of water based printing? Perhaps you’re looking for more information on its pros and cons? Unique benefits and limitations? Requirements and rewards?….Or maybe simply, how to print with water based ink?