Depends…. Generally, mats warp when exposed to high temperatures. But there are designs built to withstand a hot iron passed right over them. The mats, however, cannot withstand very high temperatures as well. The plastic and PVC model might be strong but easily warp when temperatures get too hot. When hot iron is left to sit on a self-healing mat for too long, there is a risk of weakening the mats’ bond, making it hard to work on and not forgetting shortening the mat's useful life. Ideally, the mat's ability to withstand high temperatures is influenced by the material the mat is made from. You can use heat on the mat as long as it isn't left to sit for long.