Screen Printing Inks: Plastisol, Water-Based and Discharge

Plastisol: the forgiving standard

Plastisol is PVC resin particles suspended in a liquid plasticizer, plus pigment. It does not dry in air. Left in a screen it stays wet for hours, which makes it easy to run on press and easy to print wet-on-wet. Heat is what turns it solid: as the ink warms it gels, and once its full thickness reaches the rated temperature it fuses into a flexible film. Wilflex Epic, a widely used line, lists 320°F (160°C) as its cure; the low-cure Epic Rio line is rated from 266°F to 320°F (130–160°C). Lower cure temperatures matter on polyester and other heat-sensitive fabrics.

Because plastisol sits on top of the fibers instead of soaking in, it is opaque and bright, especially over a white base, and it is the easiest ink to match to a color swatch. The cost is feel. A heavy plastisol print, white on black above all, has a smooth, slightly rubbery hand and stops that patch of fabric from breathing. Printers thin the deposit with finer mesh, soft-hand bases or curable reducers, trading away a little opacity each time.

Major ink makers now sell non-phthalate plastisol lines, and some brands specify them by name on purchase orders. One care point is specific to plastisol: an iron set directly on the print can re-melt it.

Water-based ink: soft and breathable

Water-based screen ink is pigment carried in a water-borne acrylic binder. Instead of resting on the fabric it penetrates the fibers, so on a light cotton shirt the print can feel like part of the cloth. Next to plastisol the color looks a touch muted, and on a dark shirt the garment color shows through unless the ink goes over a white or discharge base.

Curing happens in two stages: first the water has to evaporate, then the binder has to heat-set. Green Galaxy's data sheet, for example, asks for the ink layer to reach 320°F and hold there, which in a forced-air dryer means roughly two minutes of dwell. A short tunnel or a fast belt is the usual reason a water-based print washes out.

On press, the problem flips from plastisol's. Water-based ink starts drying in the mesh the moment a screen sits idle, clogging fine detail. Printers keep screens flooded, add retarders, and use water-resistant emulsion so the stencil survives the run. High-solids acrylic (HSA) inks pack in more pigment and close some of the opacity gap with plastisol. A water-based ink print also tends to fade softly with age, which is part of its appeal for vintage-style merch.

Discharge ink: color that replaces the dye

Discharge ink is water-based ink with an activator mixed in shortly before printing. Most activators are zinc formaldehyde sulfoxylate (ZFS); a newer system based on thiourea dioxide avoids formaldehyde. As the print heats in the dryer, the activator strips the garment's dye wherever the ink sits, and the pigment in the ink colors the fiber in its place. A clear discharge base with no pigment simply removes color, leaving a lighter tone-on-tone image.

Discharge only works on cotton colored with reactive dyes, which covers most cotton blanks but not all. Polyester does not discharge at all, so a 50/50 blend gives a patchy, heathered result. Some dyes resist or shift to an unexpected tone, and results differ between garment colors and even between dye lots of the same color. A test print on the actual blank is standard practice. Check how a style is dyed before committing to it: how to choose a blank and garment-dyed blanks both cover this.

The payoff is feel: there is effectively no ink layer on the shirt. The trade-offs are practical. Once activated, the ink has a working life measured in hours. The dryer must be well vented. Color matching is less exact than with plastisol. A freshly printed shirt can also carry a faint chemical smell that fades after airing and a first wash.

Plastisol, water-based and discharge side by side

The plastisol vs water-based ink comparison goes deeper on choosing between the two most common inks.

Choosing an ink by garment

The blank narrows the ink choice before the art does. A starting point:

If you are still choosing the blank, read how to choose a blank with this table beside it.

Underbases on dark garments

Any color that lets light through looks dull on a black shirt, because the black shows through it. The fix is an underbase: a layer of white printed first, set with a flash cure, then covered with the top colors. With plastisol, the white usually goes through a coarser mesh for a heavy deposit, sometimes twice with a flash between hits, and the top colors go through finer mesh so they stay thin. The underbase is shrunk slightly, or choked, so no white halo peeks out at the edges.

Water-based and discharge jobs often use a discharge underbase instead. It knocks the dye out of the cotton so the colors on top sit on near-white fiber, and the whole print stays soft. On a garment that discharges badly, though, that base turns muddy and so do the colors over it. How mesh choice changes the underbase is covered in mesh count and print feel.

Color matching on fabric

Printers mix spot colors from an ink maker's mixing system, weighing each component to a formula for the requested Pantone reference. Matching on fabric is never quite like matching on paper. The garment color, the knit texture, and whether the ink sits on top or soaks in all shift what you see. The same red reads differently on white, on a heather and on a garment-dyed tee. For brand-critical colors, ask for a strike-off, a test print on the real blank, and approve it in daylight.

Polyester adds one more variable. Disperse dyes in polyester can migrate into the ink during curing and tint a white print pink or grey, sometimes hours after it leaves the dryer. Printers manage dye migration with low-bleed inks, grey blocker bases and lower cure temperatures, so mention any polyester content up front.

Durability and care

A fully cured print in any of the three inks survives far more washes than most garments do. Under-cured ink is the real enemy: a plastisol print that cracks when stretched, or a water-based print that fades badly after the first wash, almost always missed its cure temperature or dwell time. A simple check is to stretch a test print hard; a cured plastisol film stretches and recovers, while an under-cured one cracks.

For the person wearing it, the same rules cover all three: wash inside out in cool or warm water, tumble dry low or hang dry, and skip bleach. Keep irons off plastisol prints entirely.

Environmental notes

• Plastisol contains PVC and plasticizer. It does not evaporate, so leftover ink, rags and press wash are handled as chemical waste rather than rinsed away. Non-phthalate plastisols are now widely available.
• Water-based ink has no PVC and cleans up with water, but the washout water still carries pigment and binder, so responsible shops filter or treat it under local rules. It also needs longer in the dryer.
• Discharge ink relies on activator chemistry that calls for good ventilation. Formaldehyde-free activators exist, though they are less common.

If restricted-substance compliance matters for your brand or retailer, ask which ink line will be used and whether it carries a certification; the ink maker's documentation is the place to confirm it. Specialty effects built on these bases, from metallic to glow, are covered in specialty inks.

Useful for: clothing brands, bands, skate and surf shops.