cisco said..samsturdy said..
Hi HG. This is a method I've heard of although I've never done it.
Brush a 10% solution of sulphuric acid on the area then scrub with a stiff bristle brush while it's still wet.
Wash area throughly with water and when dry paint with a zinc-chromate primer.
Apparently they use this method on airplanes. So it should be OK for your mast.
Good luck mate.
Hydrofluoric acid I believe is the best for ally and as far as I am aware zinc chromate is no longer available to the general public. Too toxic they say.
And Hydrofloric acid is the one that beads up on burnt Viton seals and belts after car fire, we train our rural firefighters about it because it can soak through the skin and enter bones where it continues migrating up the limb, this is then treated by amputation to arrest it's spread.
http://www.recreationalflying.com/threads/zinc-chromate-primer-alodine-preparation.63003/
