Scorch marks and shiny fabric

Siser’s heat-sensitive article is the clearest maker’s note we have. They name polyester, and also rayon, silk and anything you are unsure about. Their advice, in their order, is:

1. Do not press a “do not iron” or “cool iron” garment unless you can spare it. Test an inside seam if you must.
2. Use a heat press rather than an iron. An iron cycles through a range. A press is steadier, though its dial can still be wrong.
3. For polyester-based fabric, they point at HI-5: 120°C for 5 seconds, which they say avoids shine and fibre damage. On the product page that 120°C is for textiles up to 150 g/m². Heavier cloth is 150°C, still for 5 seconds, at high pressure.
4. If you do not have HI-5, they say you can lower the temperature and raise the time. The worked example is StripFlock Pro: 25–30 seconds, and do not go below 140°C. That example is not permission to rewrite every chart.
5. Use a heat-transfer cover sheet. Parchment, or the shiny side of multipurpose paper, is their stand-in.

Garment Films build the same idea into One Flex. The standard press is 140°C for 8 seconds. The chart also lists 130°C for 10 seconds and 120°C for 15 seconds, and the note says the lower temperature is for more sensitive garments.

Sublimation is hotter than any of this. Sawgrass polyester fabric is 205°C and Xpres use 190°C for a minute or more. A light scorch around a sublimation print means the shirt cannot take that dwell, or the platen is hotter than the dial. Dropping time and temperature together, without a spare, is how you get a faded print and a scorch on the same shirt. Change one thing.

Nylon and children’s polyester are the pieces most often ruined by a cotton habit. Cover them, test them, and keep plastic poppers off the platen.

Common questions

Sources

• Siser, heat-sensitive textiles
• Siser HI-5
• Garment Films application guidelines (PDF)