There are many types of sponges on the market today, many of which are suitable for use in creating pottery and studio ceramics. Broadly speaking, there are two main factions: synthetic sponges and natural sponges. In the past, many potters made a point of only using natural sponges. Recently, however, new synthetic sponges have become available which are just as useful and durable.
Cellulose Sponges Cellulose sponges are a man-made sponge which are tough and durable, and hold a large amount of water. Your basic kitchen sponge is a cellulose sponge. These sponges are not good for working with clay, as they tend to disintegrate into the clay and glazes, and wear out quickly when used to clean bisqueware. They are good all-around clean-up sponges, however.
Poly Sponges These synthetic sponges are very soft and highly absorbent. Although they are resistant to chemicals and grease, they aren’t very useful in the pottery studio, as they shredded quite easily.
PVA SpongesA high tech synthetic sponge, PVA sponges are super absorbent and durable. PVA sponges have many of the qualities of and closely mimic natural sea sponges, but with greater liquid-holding capacity. They are abrasion, shred and tear resistant. Rigid when dry, they quickly soften when wet down, especially when warm water is used. PVA sponges come in a variety of shapes and pore sizes.
Seawool Sponges (Also known as sea wool, sheep’s wool, natural sea, and natural sponges.) In addition to being a superb moisture holder, the natural sea sponge is also tear resistant. If harvested correctly, sea sponges are a renewable resource and are ecologically friendly. With larger pores than the silk and elephant ear varieties, seawool sponges are especially great for absorbing large loads of water from the interior of pots while throwing. They are also used to apply glaze to give a stippling effect.
Elephant Ear Sponges Elephant ear sponges are flat, rather triangularly-shaped natural sponges that have a fine texture and are absorbent. They are very useful during throwing to add and control the application of water during each throw. Due to their durability and fine structure, they are also useful in removing all dust from bisqueware just prior to glazing.
Silk Sponges(Also known as white silk sponges.) Silk sponges are a very nice natural sponge. They are similar to seawool sponges, but their pore texture is much finer. They are useful in glaze applications such as stippling. These sponges are also highly absorbent.