Scratch durability of automotive clear coatings : A quantitative, reliable and robust methodology

Scratch and mar durability of clear coatings are issues of concern to the automobile manufacturer and paint supplier. Scratching of clearcoats is a consequence of tribological events encountered by painted exteriors during normal service life. Several subjective methods to assess scratch durability have been proposed. These methods offer little insight into scratch mechanisms. More recently, single scratch methods have been proposed to probe clearcoat scratch mechanisms. This paper outlines a reliable and robust scratch methodology for evaluating scratch durability of automotive clear coatings. It is shown that, with appropriate characterization of tip geometry, quantitative and reproducible critical load values can be obtained. A suggested test method for scratch durability is described.