I used some wool flannel that I bought on sale and never made into a coat. Some use an old wool blanket instead of yardage. After washing and drying to "full" the wool, I stapled it to a plywood base scrounged from DH scrap wood and then draped with a leftover piece of decorator cotton twill. Free 24" X 48" ironing table top!
I researched this and read that wool makes a great base under cotton duck for steaming fabric. I think it's because of the evaporation rate compared to cotton batting. From my research, the silver cloth is not recommended for garment construction because it reflects back the heat instead of absorbing it. I don't know if this applies to quilting cottons, I love it for block fusing with tricot interfacing.