I've used duralac and monel rivots in the past for fitting stainless steel fittings on my boom.

It looks like more than the fittings. I got the same on an old boat of mine. My next mast was anodised - much nicer.

I think one problem of painting a mast is that we can do all these nice things like etch priming the outside but less than 3 mm away, the inside of the mast is unpainted and can oxidise away with rain water and sea air helping oxidise interior surfaces. Then you can get a small set of galvanic cells going and your paint blisters off again. It takes just a small speck of dirt or similar to make a zone of different electronegativity and a small cell is created and oxidation starts again.

Maybe one day we will hook our masts up to the negative of a small battery (positive to a stainless cathode) and protect electrolytically.

cheers

Phil

Hi
I had the same issue with my mast earlier this year before a refit.
Removed the mast, used paint stripper to strip all paint and removed the fittings, after the paint stripper 240 grit and ended up with 800 wet and dry with lanolin spray instead of water, mast came up like new all bright and shiny all but small areas of pitting, given that it is 30 years old. refitted all the fittings with stainless rivots and duralac. The mast has dulled a lot and now looks great like it was never painted.
Aluminium will protect it's self to a large degree if you can isolate the fittings well enough.
My advice for what its worth is strip the paint, don't repaint and spend your money on properly isolating the fittings.
cheers