Chosen by Grant England
Wetting refers to how well or poorly a liquid contacts a surface. Usually the term applies to water, where if a surface is hydrophobic it will not wet well while if it is hydrophilic it will wet well. The relative hydrophobicity or hydrophilicity of a substrate can be determined by measuring the contact angle of water with the surface. A liquid wets a surface better if it has a low contact angle with that surface. In general, if the contact angle is lower than 90 degrees, the liquid is considered to be wetting for that surface; while, if the contact angle is greater than 90 degrees, the liquid is non-wetting for the surface.