The chemistry in plain words
Polyester is a plastic polymer spun into fibres. When it is heated to sublimation temperature, the fibres soften and their structure opens slightly. The sublimation ink, now a gas, moves into those openings. When the fabric cools, the fibres close and the dye is locked inside.
Cotton is made of cellulose from a plant. It does not soften and open the same way, and sublimation dyes have no chemical attraction to it. The dye sits loosely on the surface and washes out.
What about blends?
In a blend, only the polyester takes the dye:
| Polyester content | Result |
|---|---|
| 100% | Bright, full colour |
| 65–80% | Slightly muted, soft look |
| 50% | Faded, vintage look |
| Below 50% | Not recommended |
What if we want cotton?
If you want a cotton T-shirt or hoodie, use a method designed for cotton:
- Screen printing for simple designs in bulk.
- Embroidery for logos and crests.
- DTF printing for full-colour designs in smaller quantities.
Compare methods in sublimation vs screen printing, or see our custom hoodies and T-shirts.
Why white fabric?
Sublimation inks are transparent, like watercolours. They need a white or very light polyester base to show true colour. Dark kits are made by printing the dark colour onto white fabric, which is why sublimated kits can be any colour, including black.
Frequently asked questions
Can you sublimate a 50/50 cotton-poly shirt?
Only the polyester half takes the dye, so the print looks faded or vintage. For bright colours, use 100% polyester.
Is polyester uncomfortable?
Modern sportswear polyester is soft, light and moisture-wicking. Most professional kits are polyester.