When ordinary tap water dries on glass it leaves spots of chalk etc that leaves white blobs.

We use super pure de-ionised water to clean glass. This has no impurities at all, it is just H2O.

Because we take the bits of impurities from between the molecules of H2O the water tries to fill them up again. This is why sugar, salt and many other solids dissolve well in water.

When we spray and brush the glass with this special water it attacks the dirt effectively dissolving it and lifts it off the surface rinsing it away.

When we have finished the glass is wet, because we do not touch it after rinsing. When it dries it is clear and clean as the rinse water is so pure it leaves no marks.