What Temperature Should an Iron Be for Iron-On Transfers?
The correct temperature for iron-on transfers depends on the fabric. Cotton handles the most heat (150-165°C). Polyester needs moderate heat (145-150°C). Nylon requires the lowest temperature (140-145°C). Getting this wrong in either direction causes problems - too cool and the transfer peels off, too hot and you damage the fabric. Here is the exact temperature for every common fabric.
Temperature by Fabric Type
Cotton is the most forgiving fabric. Standard cotton t-shirts, hoodies, and tote bags work at 150-165°C with 12-15 seconds of press time. Heavier cotton (canvas, denim) benefits from the higher end of this range. You have a wide margin of error with cotton because it tolerates heat up to 200°C without damage.
Polyester is heat-sensitive. Use 145-150°C and do not exceed 155°C. Polyester begins to soften at 160°C and can melt, glaze, or shrink above 170°C. Most sportswear, workwear polo shirts, and promotional t-shirts are polyester, so this temperature matters. Press for 8-10 seconds.
Poly-cotton blends should be treated as polyester. The polyester content sets the ceiling. Use 150°C and 10-12 seconds.
Nylon is the most sensitive common fabric. Use 140-145°C and press for only 6-8 seconds. Nylon softens at lower temperatures than polyester. Use light pressure and a pressing cloth.
Denim is heavyweight cotton, so it handles high heat. Use 155-165°C and press for 15 seconds. The thick weave needs slightly more heat and time to achieve full adhesion.
Canvas is similar to denim - heavyweight cotton that tolerates high heat well. Use 155-165°C for 15 seconds.
Household Iron Settings
Most household irons do not display an exact temperature. Instead, they use fabric settings. The cotton/linen setting is typically 180-220°C, which is higher than needed but acceptable for cotton garments because the actual temperature at the fabric surface is lower than the iron plate temperature.
For polyester, use the synthetic or medium setting. If your iron does not have a synthetic setting, start at the wool/silk setting and increase gradually. Press for a shorter time (8-10 seconds) and check adhesion before committing to a longer press.
For nylon, use the lowest setting your iron offers. A nylon or synthetic setting is appropriate. Press for only 6 seconds and check immediately.
Heat Press Settings
A heat press with a digital temperature display gives you precise control. Set the exact temperature listed above for your fabric type. Use medium-firm pressure for most fabrics (reduce for nylon, increase for heavy canvas). The advantage of a heat press is repeatability - once you find the right setting for a fabric, every transfer will be identical.
If you are pressing multiple fabric types, start with the lowest temperature fabric first (nylon), then increase for polyester, then cotton. This prevents accidentally pressing a polyester garment at a cotton temperature.
Signs of Wrong Temperature
Too cold: the transfer peels off after cooling, edges lift, or the entire design falls off during the first wash. Solution: increase temperature by 5°C and press again for the full duration.
Too hot on polyester: the fabric develops shiny marks (glazing), shrinks, or feels stiff and crinkly around the transfer. The damage is permanent. Solution: always test on an inside seam first if you are unsure of the fabric composition.
Too hot on nylon: the fabric melts, distorts, or develops a wavy texture. Nylon damage happens quickly and is irreversible. Solution: start at 140°C and increase only if needed.