Adhesion Defect

Poor Galvanized Metal Adhesion as well as Paint that has lost its adhesion to a galvanized metal substrate

Possible Cause

Improper surface preparation, such as inadequate rust

Failure to apply a primer before application of an oil-based or vinyl latex paint

Failure to sand baked-on enamel finishes or glossy surfaces before painting

Solution

Any rust on the metal should be removed with a wire brush; then, an acrylic latex corrosion-resistant primer should be applied (one coat is usually sufficient). New or previously painted galvanized metal that is completely rust-free can be painted with a top quality acrylic latex paint without applying a primer; however, a metal primer should always be applied to unpainted galvanized metal before applying an oil-based or vinyl latex top coat

Source: Paint Quality Institute

Adhesion Problem 1