Glass billed as being “self-cleaning” has a coating that hastens how quickly water runs down the glass. The way the water runs down the glass also changes how much dirt and other substances it can remove from the glass. The theory is that with the water washing away the dirt and grime from the glass, consumers won’t need to clean the windows with soap or glass cleaner as frequently as one would without the specialty coating.

There are two different kinds of “self-cleaning” glass: hydrophilic and hydrophobic. Self-cleaning glass coatings are not particularly popular among members of the glass repair industry, as the coating and its ability to transform how water reacts to glass can make the repair process more difficult.