Polyester
Fiber — one of 29 in the glossary
A synthetic fibre spun from petroleum-derived polymer, and the second pillar of the blanks catalogue after cotton. It is strong, holds its shape, barely shrinks, dries fast and keeps colour well, which is why performance wear, fleece and most blends lean on it. Decorating it is the catch: polyester will not accept water-based or discharge ink, it needs lower cure temperatures than cotton, and its disperse dyes migrate into plastisol under heat, so dark polyester often needs a low-bleed or blocker ink. It is also the only common fibre that takes sublimation, which bonds into the fibre itself.
A fibre that absorbs almost nothing
Polyester absorbs under one per cent of its weight in water. Cotton absorbs many times that. Nearly every practical difference between the two follows from that one fact.
It is why polyester dries fast and wicks: water cannot go into the fibre, so it travels along the surface and evaporates.
It is why polyester barely shrinks: there is no fibre swelling and relaxing to drive the change. And it is why a wet polyester shirt feels cold and clammy rather than heavy.
What it buys in a blank
Dimensional stability. What you order is what your customer wears in a year, with no first-wash allowance to plan for.
Colour retention and heather effects. Polyester holds dye well and takes it differently from cotton, which is how blended heather colours are produced at all.
Strength and abrasion resistance at low weight, which is why performance and outerwear lean on it.
The cost is hand and breathability. Pure polyester next to the skin is less comfortable than cotton for most people in most conditions, which is why blends exist.
The three things that go wrong at the press
Dye migration. Disperse dyes in polyester turn to gas under heat and move into plastisol ink, so a white print on a red shirt turns pink days later. Low-bleed ink and a lower cure are the fix.
Scorching. Polyester glazes and melts at temperatures cotton tolerates, leaving a permanent shiny mark.
Ink chemistry. Polyester will not take water-based or discharge ink, which need cellulose fibre. It is also the only common fibre that takes sublimation, which bonds dye into the fibre itself.
Common questions
- Does polyester shrink?
- Barely. The fibre was heat-set far above laundry temperatures, so expect one to two per cent at most, and that from the knit relaxing rather than the fibre.
- Why does polyester wick?
- Because it absorbs almost nothing. Liquid cannot enter the fibre, so it travels along the surface and through the channels between fibres, where it can evaporate.
- Can you screen print on polyester?
- Yes, with low-bleed ink and a lower cure temperature to control dye migration and avoid scorching. Water-based and discharge inks do not work on it.
- Is polyester or cotton better for printing?
- Cotton, for most methods — it takes more ink chemistries and has none of the migration risk. Polyester wins only for sublimation, which cotton cannot take at all.
Where this comes up
See also
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