This paper shows how a multiscale transfer function can be used to understand the impact of successive mechanical treatments (superfinishing, sandblasting and brushing) on topography. The multiscale analysis indicates that the changes of roughness induced by brushing are not uniform on the entire range of frequencies. The transfer function built with the arithmetic mean deviation (Sa) leads to identify two regimes of roughness: the ability of brushing to “create roughness” and the ability of brushing to “remove roughness” caused by blasting.