i have never had a problem with a poly batting melting from my iron, i have never actually ironed a batting without fabric covering it but there has never been a problem and just like with cotton batting not all poly batts are created equal, some pull apart and migrate alot others (like the dream poly) do not. scrim and no scrim also has a bearing on the characteristics of the batting, and you can get either one (cotton & poly) with and without scrim