Ron,
I believe you are talking about Rubbermaid Grip Liner.
Although I really cannot answer your question fully, I can add this:
I've used that material for a couple of years - maybe 3-4 - but mainly to
hold small boxes of shells in drawers. I do have a few shells sitting on it
directly and to date, I have not seen any deterioration whatsoever. The
early material came from Rubbermaid, but they seem to have ceded the
business to imports.

At 10:16 AM 3/4/01 -0500, you wrote:
>Does anyone know the long term effects of placing shells on rubber mats. The
>rubber mat I refer to is the popular brown 'lace like' rubberized product
>used in many motor homes to keep items from moving about. We had an
>earthquake here in the NW and most of my shells are on the floor. I am
>considering covering the shelves with this mat before replacing, but wonder
>about the long term effects. Any suggestions. Thanks, Ron in Olympia, WA

John Wolff
2640 Breezewood Dr.
Lancaster, PA 17601-4804