I have a 'white' large cutting mat, the one that covers my whole cutting surface. It has never dulled my blade any more then any of the other mats I use. I have Fiskars, Olfa, Omnigrid, Martelli, Polar, June Taylor, and a few no name ones. I have cutting mats on top of every flat surface in my sewing room. Honestly I like the June Taylor one the best.