Is there any cure for a mat that has warped due to being on a table in the sunshine coming in my big window?

I have used crocus cloth on mine. It's at least ten years old. I gently rub the crocus cloth over the board and it smooths out those little bumps and also picks up the lint caught in fine cracks from cutting.

Don't laugh but what is crocus cloth????

I don't know how long I have had mine. My first one got broken when I packed one time.
I am wearing out my rulers though. The printing is coming off. :-)

I never have heard of crocus cloth. What is it and where can I get it?

I have several mats. I do my work on a ping pong table and I have four "stations" set up at the four quadrants of the table. Three of them are Olfa's, and one is some other brand that I can't remember. It was the first one I bought when I went back to sewing some five years ago. It doesn't seem to be "healing" any more, but the Olfa's are all going strong.

I found out that crocus cloth is a type of sandpaper type product--on a cloth background. That will not take all the big bubbles/warp out of my mat. Any other suggestions?

I have read in a blog elsewhere that putting your warped cutting board on a
dark asphalt driveway when the weather is over 90º can correct the warp.
I hope so - I just put mine outside at 2 pm and will see how it works and let you
know. It sounds too easy but I hate to have to spend so much money on a new one. I use the 24 x 36" Olfa mat. If I have to buy new, I use my 40% off coupon at JoAnne's and that helps soften the blow....-Judy

I have the large 36X30 and love it. Have a small 12x12 that I use at the side of my machine when I need to cut peices that have just been sewn and pressed. The worst thing that can be done to a mat is to accidently expose it to the heat from the iron (had my pressing station sitting on it, bad idea). It warped and could not be straightened out, so I cut it into smaller boards to use at classes etc. Also they make great templates, just cut with a straight edge ruler and a utility knife.

I read somewhere that you have to check the thickness (mils?). The thinner ones are the kind that don't stand up. I think, but I'm not sure, that they should 6 mils. You can tell by the feel of it compared to a thin one.