Polyester is the one fabric that fights back — heat makes its dye bleed. Press it cooler, quicker, and test first.
The number on your press is a suggestion. Presses ship miscalibrated, read differently across the platen, and drift over time — the panel can say 280°F while the print only sees 240°F. What actually bonds a transfer is the print reaching 280°F for 3–5 seconds at firm pressure. So you may need to set your press higher — often 300–310°F — to get there. Dial in your press once, then trust it.
Presses read differently and drift — it's not uncommon for even new heat presses to be off by 20% or more. Answer a few quick questions and we'll get you a good starting point to dial in from.
A 2–3 second tap flattens the garment and drives off any moisture. Our film no longer needs it to bond — but a flat, dry surface still gives the most even contact, so it's worth it in humidity or on a garment that's been sitting.
265–270°F · 2–3 sec · firm 90 psi. Go as cool as still bonds and press for the shortest time — heat is what drives polyester's dye up into the print. This range is a starting point; dial it in on your own equipment.
On dark polyester keep the post-press very short or skip it — extra heat-time is exactly what triggers dye migration. A textured sheet still helps on light garments.
| Feel | Pneumatic (psi) | Manual dial (1–9) | What it looks like |
|---|---|---|---|
| Light | 20–40 | 1–3 | Paper slides out easily |
| Medium | 30–50 | 4–5 | Paper drags a little |
| Medium-firm | 40–60 | 5–6 | Firm tug to pull paper |
| Our spec — firm | 90 | 7–9 | Paper won't budge |
On a pneumatic press, set the gauge to 90 psi. On a manual clamshell, aim for a solid two-finger effort to latch, then confirm with the paper-drag test.
Closes at a slight angle, so thick seams take more force at the hinge. Great for flat tees — just latch fully for even contact.
The platen comes straight down for the most even pressure. Best on thick goods like hoodies, denim, and canvas.
Air holds identical pressure every cycle — set 90 psi once and every press matches. Ideal for volume.
Start at the low end (~265°F) on dark polyester, and press longer rather than hotter if adhesion is weak.
Test on a scrap or inside seam first — dye migration often shows up as a colored halo 24–48 hours later, not immediately.
Every press and garment runs a little different — testing is how you find the exact window for your setup.
A Teflon or textured cover sheet adds a barrier between the platen and a heat-sensitive garment.
| Symptom | Likely cause | Fix | |
|---|---|---|---|
| Pink or colored halo appears hours later | Dye migration — the garment's dye sublimated into the white ink | Lower the temp, shorten the time, use a barrier sheet, and test | Finish |
| Shiny or scorched box around the print | Too hot or pressed too long for polyester | Reduce temp and dwell; use a textured cover sheet | Finish |
| Weak adhesion at the low temp | Cooled too far for a solid bond | Add a second of dwell rather than raising temp; re-test | Adhesion |
Polyester is colored with disperse dyes that turn to gas and bleed upward into your print when they get hot. Pressing cooler (and briefly) keeps that dye in the fabric instead of in your artwork.
It's the garment's own dye sublimating into the transfer's white ink layer, showing up as a pink or colored haze — often a day or two after pressing. Once it happens it can't be reversed, so lower-and-test is the rule.
On light garments, yes — briefly. On darks, keep it very short or skip it, because the extra heat-time is what triggers migration.
Upload a design and our preflight scores how it'll press on polyester — ink density, hand feel, and adhesion, before you order.
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