It looks like someone painted your project using good aircraft technique. Good news/bad news. Th e paint looks easily strippable. Bad news...the primer looks like acid etch zinc chromate. Designed to form a great and strong bonding primer. The best stripper I have found for that is regular airplane paint stripper. It will take some "agitation" as the stripper works. When you do the final wash off of the stripper use aluminum wool or 3M green pads and you will have your clean aluminum surface . Same procedure for any paint you have there if not zinc chromate type.
"If it can't be reduced, reused, repaired, rebuilt, refurbished, refinished, resold, recycled or composted
then it should be restricted, redesigned or removed from production."