Managing variables associated with the substrates you use is critical to quality. Find out how to work with some popular, but picky, materials.
With polystyrene (HIPS) there are no trade secrets. This substrate is one of the easiest and fastest running substrates for screen printing. It’s easy to handle with a rigid, flat, smooth surface. Markets for polystyrene are endless. We use this material in all of our business segments in printing, plastic fabrication, environment, and retail applications.
A few things to watch for are static electricity and bruised product (which shows scuff marks on the styrene). The material can warp when the manufacturer bands it while it’s still warm.
We mainly print on pressure-sensitive vinyls, but we also print on drywall, wood, and most surfaces. On wood we must control the absorption rate along with the print speed. We also need to know how many printing passes are necessary for opacity or brilliance.
Drywall has a paper coating, so we have to print that quickly. Then we have to add a number of passes to get the color we need. We did this for a museum (Figure 6) in Manhattan. We work with architects here for wall graphics (Figure 7). We produce a test print and then decide to add passes until we see the desired effect. Printing on metal requires surface preparation to remove oils and residue. We clean surfaces scrupulously before printing.
There are variables in printing. Under or over curing is an important one. You need enough UV energy (measured in joules/cm2) to cure the ink properly. It’s a technology now, not an art.
Frank Torlucci, VP of manufacturing and production manager, says the market for fleet graphics is the best for Selecto-Flash (Figure 8), The company also uses pressure-sensitive substrates to produce signage and decals for windows, doors, and walls.
“We’re printing on vinyl and use screen or digital printing with conventional solvent-based or UV inks. However, we do a lot of things on other specialty substrates, such as styrene, foam core, plastic core, and cardboard,” he says. “At present, we don’t use water-based inks—only solvent or UV.”
Did you enjoy this article? Click here to subscribe to the magazine.