Every screen printer knows that the demand has grown for prints with a soft hand and, often, for prints with a more subtle look. Adding water-based screen printing to your shop’s options can help you appeal to and capture customers who want the softer look and feel of water-based inks. If you’ve never used water-based inks, here are 10 tips to get you started with water-based screen printing.
Many printers plan for a lot of flash curing when they print with plastisol inks and will often plan for overlapping colors to increase the opacity of their design. Because water-based inks don’t “cure” — the water evaporates out, leaving the pigments to bond with the fabric — multiple flash cures aren’t possible. Under a flash cure unit, it takes some time for the water to evaporate. When planning your artwork for a water-based print, carefully separate your artwork so that there are no overlaps in the inks to avoid color mixing without flash curing.
Water-based inks are much thinner than their plastisol counterparts. If they flow too quickly through your screens, your image might bleed. To slow the flow, use higher mesh-count screens. Water-based inks usually are printed with mesh counts between 156 and 200 counts, with the higher mesh count used for more detailed prints and lower mesh counts used for prints with high-coverage.
Proper screen prep always matters, but it’s even more important with water-based. That’s because the thinner nature of water-based inks allows the ink to find its way through pinholes or imperfections even more easily. When preparing a screen for printing with water-based inks, remove the haze, clean the screens, degrease the screens and allow the screens to dry completely.
While most emulsions are waterproof to some degree, the emulsions used for plastisol printing generally won’t stand up to the constant moisture exposure that comes with water-based printing. To keep your stencil from breaking down during water-based jobs, it’s a good idea to use a waterproof emulsion that’s intended for printing with water-based inks.
Even with a waterproof emulsion, stencil breakdown can occur during water-based printing. There are steps you can take to fortify your stencil. After washout, you can expose your stencil one more time to reharden any portions of emulsion that had softened. You also can use a chemical hardener whose purpose is to shore up stencils. Hardeners are sprayed onto the stencil, then allowed to dry for 24 hours.
As with plastisol inks, there are a host of ink additives that can help you get the performance you want from water-based inks. Retarder slows the drying of ink on screens. Saturate serves as a wetting agent that helps water-based inks soak into the substrate more deeply. Thickener will increase the viscosity of your water-based ink when you want it to flow less easily. Cross-linker helps water-based inks cure faster at lower temperatures. Binder booster helps pigments hold faster to fabrics, making your water-based print brighter. Stretch additive will allow your print to stretch without cracking.
Before printing, adjust your press’s off-contact distance to the ideal distance for water-based inks. A 1/8-inch off-contact distance between your screen and your substrate is a good place to start, and your screens should hit your pallet at a perfectly flat angle.
One of the biggest challenges of water-based screen printing is that inks can and will dry out on the screens as you print. You can take measures to slow this process. First, you can use an ink additive to slow the evaporation process. Keep the ink replenished on the screens during printing. You also can mist the ink on the screen using a water-filled spray bottle, and be sure that there are no fans or breezes blowing across your press area when printing with water-based inks.
Printing with water-based inks requires less squeegee pressure than plastisol inks. Use a soft to medium squeegee, such as a 55- to 65-durometer or a 55/90/55 triple-durometer squeegee. When printing, use a greater squeegee angle and apply minimum pressure.
As mentioned, water-based inks cure completely differently than plastisol inks: The water evaporates out, leaving the pigment behind. To ensure that the pigment is bonded to your substrate, you have to be sure that the water has fully evaporated out of the ink. First and foremost, follow the curing specifications of your water-based inks. Many manufacturers recommended a forced-air dryer for water-based inks, so gas conveyor dryers with that option are typically a better option than electric dryers. With a conveyor dryer, be sure that there is adequate air flow, and slow the belt on the dryer to allow for sufficient dry time.
Water-based inks often get a bad rap for being difficult to print with. In reality, printing with water-based inks isn’t difficult; it’s just different than printing with plastisol inks. By following these tips, you can be well on your way to successfully screen printing with water-based inks to provide your customers with the soft hand and soft look they seek.
Want some more tips on printing with water-based screen printing inks? Check out these blogs: