I only know of powder coating as a method of applying the final paint. My questions are:
- What are other options of painting aluminum panels (e.g. aluminum gate) for outdoor use?
- How do they compare to powder coating in terms of durability?
I'm just summarising the answer I got from Ed Beal within the comments, for future reference.
When I was in the Air Force zinc chromate primer on the aluminum is what is used on air craft for the primer, there are many types , I found the self etching zinc chromate the best for aluminum then whatever paint you used stuck to the primer. I had an aluminum step van that I used for my scuba business I had painted it with my logo and it was used in tough conditions salt water soaked gear and at the coast 30-40 times a year the paint held up quite well even on the inside where gear bumped the walls when turning. So give etching type zinc chromate it works and may be cheaper than powder coat.
When I asked him about the situation where the aluminium panels are already powdercoated, he replied:
If it is already coated the zinc chromate can’t bond with the aluminum so it won’t do any good. Because aluminum oxidizes and most paint won’t bond well with it is the reason to use a primer, powder coating is sprayed and baked it should be as good as a primer.