Ink additives

Plastisol additives

• Curable reducer: thins thick ink so it prints more easily. It cures with the ink. ICC lists 1–10% by weight for its 1110. Avient says 5% of its curable reducer lowers most plastisols’ thickness by about 25%, and over 10% can lower opacity and bleed resistance and affect cure.
• Never mineral spirits or too much non-curable reducer: Davis says with too much, the plastisol “will not fuse no matter how long or how hot the cure.” Lawson says never add mineral spirits. ICC says plasticizer-only reducers are used sparingly, about 0.5–2% at most.
• Stretch additive: lets prints stretch on Lycra and spandex without cracking. ICC lists 3 parts ink to 1 part 1199 by weight (2:1 by volume). It is not low-bleed, so test on poly.
• Puff additive: makes plastisol rise in the dryer. ICC lists a maximum of 10–15% of its 220 by weight. Lawson says heating above 350°F can collapse puff.
• High density additive: turns flat ink into ink that builds sharp, raised edges through a thick stencil. Lancer says add 20% by weight of NX6135 to its NX inks, with a full cure of 275–320°F for 1½–2 minutes.
• Soft-hand / extender base (curable base): a clear base that softens the feel and stretches ink further, but lowers opacity. ICC suggests 20–25% by volume of its 720 in 700 Series ink on light shirts. It can lower bleed resistance.
• Low-cure additive: lowers the cure temperature, which helps on polyester and heat-sensitive bags. ICC says 5–6% by weight of its 3804 brings most plastisols under 300°F. Low-cure inks usually cure around 250–300°F; standard plastisol around 260–330°F, by ink.
• Catalyst / bonding agent (nylon): a hardener that helps ink grip nylon. ICC mixes its 900 Series 20 parts ink to 1 part catalyst by weight (16:1 by volume). Pot life is 4–8 hours, so mix only what you need.
• Viscosity buster: a strong reducer for thick whites and blockers. Avient says start at 0.5% and stop at 3% by weight.
• Dulling / suede additive: ICC lists 2% by weight of its 222 to cut gloss, or 10–15% for a suede look.

Water-based and discharge additives

• Retarder: slows drying in the screen on hot or breezy days or with fine mesh. Matsui lists 1–5% Retarder MG. CCI lists 3–5% of its WB Retarder and warns over 5% can slow or stop a full cure. Green Galaxy lists 2–3% (max 5%) of its Compound ND.
• Thickener: raises thickness so halftone dots hold. Matsui lists 0.25–1% Thickener B, mixed with a high-speed mixer.
• Fixer / cross-linker: improves wash and rub fastness. Matsui lists 1–4% Fixer WF-N. Green Galaxy lists 1.5% Warp Drive, with a mixed-ink life of 24 hours.
• Discharge activator: the powder that makes discharge ink remove the shirt dye during curing. Avient’s Aquarius line uses 6% Activator ZF, used within 8 hours. Matsui says its discharge agent is typically 6%.

Mixing brands is a test, not a sure thing: ICC says its additives were only tested with its own inks. Weigh additives, write down what you added, and wash test before a run.