The principle is exposing a coated test panel to a liquid by one of three specified methods (the immersion method using a single-phase liquid or a two-phase liquid, a method with the use of an absorbent medium, and the spotting method) and evaluating the effects of exposure by criteria agreed in advance between the interested parties, these criteria usually being of a subjective nature. Method 1 is intended for more resistent coatings requiring longer periods of exposure than those which may be tested by method 2 or method 3. Applies to a single-coat film or a multi-coat system of paints.