Stylus methods for measuring surfaces have sometimes been blamed for causing damage to the surface because of the stylus pressure. This paper investigates this possibility and develops a ‘potential damage index’ which takes into account the instrument parameters, static and dynamic, and surface parameters. All types of surface are considered, both periodic and random. The paper shows that the stylus method is often misjudged, that stylus damage is rare and that any damage observed is likely to be due to the operation of a skid in the instrument.
