Discharge ink.

Discharge ink carries a sulfoxylate reducing agent that breaks down the garment's dye during curing, so the fabric's own fibers hold the image instead of a film of ink lying on top. The blank decides the result as much as the ink does: cotton dyed with reactive vinyl sulfone dyes drops back toward an off-white, vat dyes resist the paste, and plenty of garments land on a tan or pink nobody chose. It also needs full cure temperature to fire, so a cool dryer gives you a gray, half-discharged print. Test each dye lot before the run, because a blank that will not discharge still costs you the garments, the press time and the reprint.