For quilting you don't want to use a soft ironing pad. It's best if it is very firm. I put one layer of cotton batting and then one layer of duck cloth (canvas) on my small ironing board that I use mostly for pressing blocks and for the big board I put one layer of cotton batting and one layer of cotton fabric. If the fabric sinks at all into the pad it will distort the fabric a lot more then you may think. As posted earlier be sure the ironing board you use for the big board has four legs not the T legs, it will have to support more weight and a wimpy ironing board won't hold up for long.