My Polder ironing board cover has 1/2 inch foam on the bottom. I would guess that this is a custom foam that is heat resistant because there is not even a hint of meltdown anyway. I would use 2-4 layers of Warm and Natural to get the pad feel of a modern ironing board. Most folks I know (and all the quilt shops) that have these wider boards have only 2 layers of Warm and Natural - if you aren't pressing clothing, you don't need the extra padding and your edges are more sharp. I still press clothing (shock!) and don't have room for 2 boards, so haven't gone that extra step to a big board.