is 35 years old, has never been painted, or treated in anyway.
Yes it is grey, and has always has been, and always will be.
There is ONE reason to paint
a mast, and that is cosmetic. If you have a mast made of inappropriate alloy that will actually corrode itself to pieces paint
is not likely to help. (Do you paint the inside of the mast????)
Painting does nothing to protect against galvanic corrosion
, that you have to take care of by careful hardware