Method for assessing painted surfaces in synthetic material

A metal and a plastic test plate are joined in a common plane parallel to each other or in planes partially covering each other and paint layers are applied to the entire surface, then dried and hardened. Paint is applied to form a wedge-shaped thickness gradient across the test plates. Optical measurements are made in a grid shaped pattern to determine the surface properties influencing the visual aspects and layer thickness is measured on the metal plate only. Preferred Features: Both test plates are rectangular and are connected either by their edges or rear faces. e.g. by use of adhesive tape on the non-painted rear faces or in the case of an overlapping connection by use of double-sided adhesive tape. Surface properties influencing the visual impression are measured over the entire surface of both the plastic and metal test plates. The thickness of the wedge shaped layer on the metal test plate is determined by a method suitable for use only on metallic substrates. Measured data from each point is entered in correlation diagrams comparing visual characteristics in relation to layer thickness.