After I read this I took my old mats and put them in the tub to soak. Then I put my new mat on the table and used it for the first time. I was amazed at how well my rotary cutter worked on it! On the old mat I thought I was going to have to replace the blade again! I am so glad some generous quilter was kind enough to share that old mats ruin your blades....Another reason this is my second home!! :D :thumbup: