Self-Cleaning Glass

A British invention of coating glass with a thin layer of titanium oxide has been found to give glass self-cleaning properties. Titanium oxide is found in food, toothpastes and sunblock -- and is usually a white powder. When used in nano-scale layers however, it is transparent. The titanium oxide allows glass to absorb sunlight, which causes a photocatalytic effect [PDF] -- resulting in a break down of dirt. It also makes the surface of the glass hydrophilic -- meaning that water droplets of the glass attract each other, forming a sheeting that runs off, instead of drying as individual droplets. Cool!