What does a straightedge or guide coat help assess on a repaired surface?

• A. High and low spots
• B. Paint color match
• C. Panel thickness
• D. Weld integrity

Answer: (A)

Assessing surface flatness—finding high and low spots on a repaired panel. A straightedge laid across the surface will reveal gaps or rocking where the panel isn’t perfectly even, indicating high or low areas that need attention before coating. A guide coat, a light contrasting spray or powder, is used during sanding to visualize irregularities: high spots are shaved down and lose the guide coat first, while low spots retain it longer, clearly showing where more material or sanding is needed to bring the surface to uniform flatness. Paint color match, panel thickness, and weld integrity are important topics, but they don’t directly reveal the flatness of the finished surface in the same way.