LIXIL Corporation of Japan sells an exterior wall coating, called Microguard, that mimics the self-cleaning bumps on snail shells that allow microscopic pockets of water to collect. The company developed a silica coating called Suitewall that can be painted on exterior wall tiles to protect them from exhaust, smoke and other pollutants. Silica, an element found naturally in soil, forms microscopic bumps to which moisture in the air easily adheres, creating the same kind of tiny dirt-repelling pools found on a snail's shell. The tiles are then washed clean every time it rains.
A pattern of tiny bumps on a snail shell creates microscopic pools of water. Oil-based contaminants "float" on these tiny pools, and when rain hits the shell the dirt is easily washed away.
Cleaning building exteriors is a labor-, water-, and chemical-expensive task. By using a self-cleaning surface, building and home owners can allow the rain to wash their surfaces.