The role of surface profile in assuring good adhesion of protective coatings is relatively well understood. Much of the research upon which this understanding is based was conducted decades ago, before the advent of many commonly-used computerized measurement systems. In particular, the measuring microscope method of determining depth of profile has long since been replaced in related applications by optical interferometric profilometry. That technique and its application to our field are discussed and the three devices commonly used to determine surface profile of blast cleaned surfaces in field applications are reviewed. The devices in question are the visual comparator, replica tape and stylus roughness testers. We compare measurements using these different approaches for evidence of relative bias and discuss errors of measurement and the relationship of those errors to the area sampled.