We begin with two strange words, which in some ways are opposites—and in other ways are similar.

Welcome to the fascinating world of wetting.

First, let’s keep this simple. Let’s only think about water—as opposed to oily materials—that is deposited onto coatings, windows, mirrors, the leaves of plants, etc. The water (in the form of rain, steam, fog, etc.) may form droplets on the surface, or it may spread into a thin film. A hydrophobic substrate causes the water to form droplets; a hydrophilic coating, however, causes the water to spread into a thin film. But how do you keep these two terms straight, given that they sound so similar? Continue reading →