Protective Coatings are engineered to fulfil certain performance criteria when applied according to very specific dry film thicknesses. Dulux Product Data sheets always include the minimum, maximum and recommended wet film thickness and corresponding dry film thickness that the coating is to be applied. To measure the wet film thickness during application, a wet film comb (also known a wet film gauge) is often used. It is a very simple and quick tool for measuring the film thickness of wet paint. A wet film comb is a rectangular piece of metal or plastic with teeth of various lengths, each representing a different film thickness. The longest teeth are at the top and bottom of each side of the rectangle.