Symmetrical brain coral “Diploria strigosa”

You may be surprised to learn that the number one reason for a foggy mask is a dirty mask. The moisture forming inside your mask has to attach to something. That something is dirt specks and oils. Moisture cannot easily attach on a very clean mask. With a clean mask the moisture sheets down and collects at the bottom instead of fogging. Moisture also can attach to the microscopic imperfections in the glass. That is why anti-fog, baby shampoo or spit works. They act as surfactants that reduce the surface tension of the condensing water, making it less likely to cling to the glass.