Diane: One product which was very popular in the mid to late 80's was "Pyrell". I do not recommend this foam product because it has been verified that it does decompose and will adhere to whatever has been resting on it. It also turns to a dust like material, which can become airborne. It is gray in color and does come in various thicknesses. It was most popular in the Army Museum System and widely installed. I understand most of the museums are now removing it from their collections storage. Product literature was collected to examine its contents etc. At that time, the product was touted as the perfect liner. As in all molecular and biological life-things will turn to dust sometime! Sarah (Fort Dix Museum Curator 1984-86, Director Historic Speedwell)