A hard surface is much better to press quilt blocks and pieces if you press or starch a lot. If the fabric sinks in the board just a little, it will distort the fabric that you won't notice but piece after piece or repeated pressing and all of a sudden nothing seems to match just right. I have plywood, one layer of Warm and Natural and then cotton fabric. On my small ironing board, I used duck canvas, wet it and let it dry on the board- super taut.