Painting powder coated aluminum
When working with powder coated surfaces, priming is an important part of the process of repainting. Select a primer appropriate for the alloy in question, whether aluminum or steel. After the first attempt at sanding, use the primer to test the adhesion level of the area. Apply a small spot of primer and allow to dry for 20-30 minutes. Attempt to wipe the spot off. If it wipes off, or smears, it is an indication that there is not enough adhesion to continue. After sanding to remove the powder coat, the bare area will need a full coat of the primer to allow the paint to adhere. Consult a professional for the proper primer for the project.
Selecting the right paint for the job is essential when painting over powder coat. Even with the right primer, certain paints may not adhere completely. Epoxy-based paints will stick to most surfaces, but may be costly and limited in the colors available. Enamel paints may be a better option cost-wise and should adhere well to primers needed for metal alloys.