I painted mine a couple of years ago with Epifanes two part polyurethane. My boom was originally powder coated in 1980. I sanded off the powder coating being careful not to sand off the original primer they used under the powder coating. It took three coatings of the Epifanes. but came out with a really tough finish that looks like a brand new powder coated boom. After two years its still in pristine condition.
The boom end caps I had my neighbors body shop paint with car paint, I assume also two part polyurethane (I wanted them black instead of white). They used an auto body aluminum primer under the paint,(brand forgotten) and it came out just as good. Still in pristine condition. They also did a small hatch for me that is in sun 24/7 (black color) and still looks pristine. Two part polyurethane is car paint, so holds up very well to UV.
My friend had her mast and boom done with Awl Grip 2-part polyurethane about 7'ish years ago. Pretty much the same thing as the Epifanes two part polyurethane I believe. She sold the boat last year , but both mast and boom looked pristine. The only problems I saw were spots where stainless bolts were not properly isolated from the aluminum.
I took my boom to my work shop and just rolled and tipped the Epifanes. It was pretty forgiving to apply, but took three coats to get a nice even white finish. Not cheap stuff, but I think its well worth the price.
