Wishab sponges are a dry cleaning sponge for use on soiled surfaces such as murals, wallpaper, frescoes and even textiles. Dirt particles are absorbed into the sponges surface which in turn, crumbles away during use. The Wishab sponge is used dry. It is particularly useful for cleaning of smoke damaged surfaces. The Wishab sponge comes in three grades of firmness, soft, hard and extra hard. The soft grade of sponge is the most commonly used, but the grade you use will depend on the sensitivity of the surface to be cleaned