New cutting mat curl
I finally got my BIG cutting mat - 36x59 - on Black Friday sale at JoAnn. Took it home and it wouldn't unroll completely. You know how that is. DH had a great idea that I didn't really expect to work, but I tried it to make him happy. Guess what. It worked!
Roll the mat the opposite direction from it's curl and put some bungee cords around to hold it. Fill the bathtub with HOT water and submerse the rolled mat. Turn it a few times or put some weight on it to keep it under water. After about 10 minutes take the wet heated mat to a cold floor (I have ceramic tile) and unroll it with the inside curl to the floor. The weight of the mat takes any remaining curl out, and the cold floor quickly cools the mat flat.
It worked great for me. Hope it works as well for you.