Self-cleaning glass is float glass with a special pyrolytic coating which works in two stages. In the first stage, the coating reacts with UV rays from the sun to generate a photocatalytic process. This causes the dirt particles on the surface of the glass to break down. Secondly, when rain lands on the glass, the water is attracted to the surface by the hydrophilic (water attracting) properties, causing it to sheet evenly across the glass, washing away loose dirt and drying without spotting.
Naturally, the glass must have full sun and rain exposure, and not be shaded by structure or the like. It’s ideal for hard to clean surfaces such as rooflights and canopies. The coating does not like salt water deposits and so it is not as effective near the sea.