Dry-cleaning sponges are made of vulcanized rubber. A miniscule percentage
(less than 30 grams per 500 kilograms of sponges) of mild soap is impregnated
during the manufacture of the sponges. Their unique pore size effectively
removes dirt, soot, and smoke residue from a variety of substrates including
walls, books, wood, paper (including wallpaper), textiles, and metal. Each
sponge measures 6 x 3 x 1-3/4 in.