Which of the following is NOT a method for testing surface profile?

Visual inspection is not typically considered an accurate or reliable method for testing surface profile. While it can provide some insight into the characteristics of the surface, it tends to be subjective and can vary significantly between different inspectors. Without precise measurements, relying on visual inspection alone does not meet the rigorous standards required in coating inspection.

On the other hand, methods such as comparator and coupons, replica tape, and digital surface profile gauges provide measurable, quantitative data that allows inspectors to determine surface profile accurately. These methods are institutionalized in industry standards and provide a consistent approach to assess surface preparation and ensure it meets the specifications necessary for successful coating application.