I wouldn't use the wool mat for starching or anything wet. Agree with
Onetomatoplant that it will smell. The wool mat is good when you
are pressing your blocks. You don't need steam. It creates its own
steam when you press on that mat. I put a piece of muslin fabric
over it before pressing. I followed Sharon Schamber's method for
my pressing board. I have two sizes. I covered my regular ironing
board with a big board. Works well. Here's her video.
https://www.youtube.com/watch?v=4LGbXou_u4c