NOCTI Collision Repair and Refinishing Technology Practice Exam 2026 - Free Collision Repair Practice Questions and Study Guide

To identify high and low spots, you rely on a simple, direct method to reveal surface deviations: a straightedge and a guide coat work together to map the panel’s flatness. Placing a straightedge across the surface lets you feel or see where gaps occur—high spots cause the edge to rock or touch only at edge points, while low areas create noticeable gaps. A guide coat adds a visual cue: a light contrasting layer sprayed over the surface, which, during sanding or blocking, is removed more quickly from high spots and remains in low spots, making those low areas obvious. This combination gives a clear, controllable way to level the panel before finishing.

The other tools aren’t as effective for this purpose. A micrometer gives exact measurements of small features on parts, not the overall contour of a large panel. A magnet is used for locating magnetic materials or fasteners, not surface flatness. A paint gauge checks how thick the paint is, which helps with coatings but doesn’t directly reveal the underlying high/low geometry of the panel.