What must be done if a self-etching primer dries overnight?

When a self-etching primer dries overnight, it can create a surface that may not adequately bond with the topcoat if applied directly without any preparation. Lightly scuffing the dried primer helps to create a mechanical bond, which increases adhesion between the layers. This process also enhances the overall durability and finish of the painted surface.

In contrast, completely removing the primer would be unnecessary and labor-intensive, especially if it has adhered properly. Sanding aggressively could damage the primer itself, undermining its intended function. Additionally, painting directly over the dried primer without any surface preparation may lead to poor adhesion and potential issues with the topcoat. Therefore, lightly scuffing or recoating is the best practice to ensure a successful application of the topcoat.