NOCTI Collision Repair and Refinishing Technology Practice Exam

A guide coat is used to show how flat the surface is during sanding. By applying a thin, contrasting layer over the surface, you can clearly see where material needs to be added or blended. As you sand, high spots contact the block and remove the guide coat, while low spots retain more coat. So the remaining guide coat highlights low areas that still need work and the bare areas indicate high spots that have been leveled. This helps you achieve a smooth, even finish before paint. It isn’t about color matching, metal strength, or primer adhesion.