the one that is warped can be fixed. if you want it.

I cut one in a circle and glued it to the top of a rubbermaid lazy susan works great to square up quilt pieces up to 8 inches

I put one under my portable sewing machine when I put it on my dining room table.Keeps from scratching the table.

I have a large mat that warped. I took it out on my patio and let it lay flat in the sun for about 3 hours. I brought it in and slipped it under my living room area rug (I have tile floors). I left it u der the rug for several hours. it was about
90% flatter. At least I can use it now.

Don't set you pc on it either! Ask me how I know. LOL

Have you tried soaking it in water until it saturated and then laying it flat with weight on it. I read that on here.

If you think you might ever be interested in the "confetti quilt" keep those old cutting mats. You can use the back and you certainly don't want to use a good mat. For this technique you cut and cut and cut and I don't think a warp would hurt anything either. I love the lazy susan idea and cutting them into small cutting mats. Thanks everyone.

This is a great idea!

I too have cut warped mats into smaller pieces to use in small area, I keep a small mat section in my sewing kit that I take to class, I have several scattered around my sewing area and at least one by my ironing station to trim seams on, you all have great ideas, this is the best place to find out the 411 on everything to do with quilting

I tried that. It didn't work for me. I threw that one away...unfortunately. I could have cut it up into smaller pieces, I think, as someone suggested.