All depends some glass has polish on it that causes them to bead but i love these type of windows cos there easy to do,a lot of old thin glass sheets and is also easier to clean.Hydrophilic glass sheets and hydrophobic beads,it all depends on what happens at the factory in the process when making the glass i`ve been told that under a microscope hydrophilic glass has smaller holes in the glass allowing water to sheet easier over the glass, where`s hydrophobic glass has larger 1`s allowing water to get trapped in them.This could be true but could also be completley wrong lol.