I would suggest turning down the heat. My first time out with my mat I used my iron on the same high heat as before using the mat. I made a minor mess and now have a discolored place on my wool mat. It is a good reminder to turn down the temp. My quilting group that meets online just talked about this yesterday. Also, if you use spray starch starch, don't use it on your wool mat. Water, yes but not starch. Several of my group mentioned making a muslin cover that can be tossed in the wash periodically keeping the mat clean.