What color is typically used for a guide coat in sanding?

A guide coat is typically applied in contrasting colors, such as black or blue, during the sanding process in auto body repair. The purpose of the guide coat is to highlight low spots, imperfections, or areas that have not been sanded adequately. When the technician sands the surface, the guide coat will wear away, revealing the underlying color of the panel or additional primer layers. The contrasting colors make it easier to see where material has been removed and to ensure a uniform finish.

Using contrasting colors maximizes visibility over a variety of substrates and helps ensure thorough sanding, which is crucial for achieving a smooth, level surface ready for paint. While other colors like white, red, and green may be used in different contexts within the industry, they are not typically the standard for guide coats, as they do not provide the most effective visibility for spotting unsanded areas.