How do you know when enough basecoat has been applied using coverage cards?

Using coverage cards is a widely accepted method in the painting and refinishing process to ensure that enough basecoat has been applied. The correct indication that sufficient basecoat coverage has been achieved is when the checkerboard pattern is no longer visible. This principle is based on the fact that the primary goal when applying a basecoat is to obtain an opaque layer that effectively conceals the underlying surface.

When the basecoat is applied, it must cover the base color or the underlying substrate completely. The checkerboard pattern serves as a visual guide; once the basecoat effectively covers this pattern, it indicates that enough paint has been applied to achieve proper opacity. This is crucial to ensure a uniform finish and avoid issues like color variance or insufficient coverage that could impact the final appearance of the paint job.

Other options, while potentially indicative of other aspects of the coating process, do not specifically measure coverage in the same manner. For instance, a complete change in color of the cards might suggest some level of coverage but does not directly correlate with optimal paint opacity. Similarly, if the card becomes transparent, this could imply inadequate coverage. A smooth paint surface is important for quality but doesn't necessarily indicate that the desired basecoat thickness has been reached. Thus, recognizing that the checkerboard