[Expert advice] Which automotive spray primer to choose

When a surface is painted, primers do several jobs at once. Besides improving adhesion, they can build an anti-corrosion layer, neutralize rust and hide minor surface defects. By the order in which they are applied, primers are either primary or secondary. The right primer, or the right combination of primers, has to be chosen for each particular job, and that means knowing what each of them is for and how it behaves.

Primers are either primary or secondary. Primary primers are applied directly to the metal surface as the first coat. Secondary primers go over the primary ones: they create a cushioning underlayer and fill minor defects, so that the surface is as smooth and uniform as possible before the paint is applied.