I have been using a Rubber table mat that is .08" thick with 2 layers and the mats don’t seem to last after a couple of years of use. the mat eventually becomes insulative and hard. the resistance goes well into the 10^9. I’ve noticed that if an item e.g. meter has covered a section of the mat for a long period of time the surface underneath the meter is pristine. All areas outside of the meter will be a slight darker color. In one case we had a 30" x 60" worksurface mat with a second 24" by 24" mat on top of the center of the workstation and all the area under the 24" x 24" mat is like new and all areas outside of at 24" x 24" mat is aged. Its almost looks like someone used an airgun to spray the surface. The work environment is highly controlled 65-72F with humidity between 30-60 % RH.
Any recommendations on how to make this material last longer. Any white papers on non rubber matting which are the pros and cons of alternate material?