Pilot Supplies, Avionics, and Homebuilt Aircraft Parts from Aircraft Spruce and Specialty Co.
sells the materials needed for stopping corrosion and prepping aluminum for painting. Their materials are of the nature of those used to preserve aircraft in a salt water environment, such as on an aircraft carrier. Their website is useful.
When I repainted my mast and boom, I used their alumiprep #33 and alodine #1201, buying a quart of each, and had excess after prepping my 34 foot mast and 11 foot boom. Instructions for use come with the order. They are very easy to use.
I didn't take all the paint off my mast and boom. I removed fittings and sanded until I got all the loose paint and corrosion off. Paint that was well-adhered stayed on the mast. I painted both mast and boom with a brush and put on two coast of Interlux Brightsides. I had a couple of minor runs on the mast, but I thought it looked great for a thirty three year old boat.
It still looks pretty good after a year of use including stepping and unstepping the tabernacled mast myself using the boom as a lever, and hauling the boat on my trailer with the mast laid across padded pulpits and center support.