I don't know if this has ever been posted before on this site, but this may be of value to anyone making booms using black Goldspar mast material, or just wanting to touch-up or match the finish.
I'm in the process of assembling three rigs for my old Dumas boat. I've purchased three black Goldspar masts, and am using the masts (natural aluminum Goldspars), that came with the boat, to make the booms.
Being a retired gunsmith, I have on hand a supply of Brownells' Aluma-Hyde II Aerosol, a non bake-on Epoxy paint for refinishing aluminum gun parts, such as actions,scopes and mounts.
The black semi-gloss, stock# 083-002-112 is an EXACT match for the factory black finish on the Goldspar masts. I made five booms of the natural aluminum masts, and one of black mast material. I sprayed all of the natural booms with the Aluma-Hyde, but only the bare edges where I sawed off the sail track on the black boom. On close examination, it was impossible to tell one from the other.