People have used sponges for both household and hygiene purposes for centuries. Artificial sponges were developed in the 1940s by the DuPont company. Due to their attractive appearance, uniform size and superior absorbency, they have largely replaced natural sponges.
A sponge draws water into itself because its surface is cellulose. Cellulose surfaces attract water molecules because the holes, nooks and crannies of the surface allow water molecules to cling. By contrast, non-cellulose surfaces such as wax or plastic will not absorb water because they do not allow water molecules to enter through their surface. In a sponge, the water spreads out along the cellulose surface and saturates it. This is what makes sponges absorbent.
Natural sponges are the skeletons of a simple kind of sea animal. Since ancient times, they have been harvested by divers and dried for household use. Synthetic sponges are made of cellulose derived from wood pulp, sodium sulphate and hemp fiber. Chemical softeners are used to break the cellulose down into the proper consistency, and bleach and dye give synthetic sponges their color.
Why Synthetic Sponges Absorb More Water
Natural sponges are products of the environment, and their chemical structure is predetermined. A company that makes artificial sponges, on the other hand, has the ability to adjust the chemical structure of the sponge's plastic. By adjusting the sizes of the holes in the sponge, manufacturers can design sponges that attract the water as efficiently as possible with a given mass of plastic. They can also tailor the thickness of the sponge to give it comfortable elasticity.