Polyester

Polyester is a synthetic fiber made from petroleum-derived polymer (PET), extruded into filament and spun into yarn that's inherently more durable, moisture-resistant, and colorfast than cotton. It doesn't absorb water the way cotton fibers do, so it dries fast and resists shrinking, typically under 2% residual shrinkage versus cotton's 3-5% or more.

It's the base fiber for nearly every performance tee and sublimation blank on the market — Sport-Tek's PosiCharge line and most all-over-print blanks among them — because 100% polyester takes dye sublimation cleanly and moves moisture off skin fast. We've had 100% poly tees come back from the dryer with a screen-printed logo bleeding a faint red halo into the surrounding white ink; that's dye migration, and it's the single most common polyester complaint we field.

For screen printing on polyester, spec low-bleed plastisol ink and, on darker or red/navy fabric, a poly-specific ink system or blocker base — standard plastisol lets disperse dyes in the fabric migrate up into the print under heat, often showing up hours or days after curing, not immediately. For sublimation or DTF work, polyester is simply the correct substrate and none of this applies.

The recurring mistake is treating every polyester tee like it will print exactly like cotton under a standard cure — dye migration is a heat-and-time reaction specific to disperse-dyed polyester, and it can quietly ruin a run that looked perfect straight off the dryer. Always test cure on the actual fabric color and poly percentage before committing to a full order, especially on reds.