You can re-anodize a mast. The shop I use for anodiziing my custom parts, Metalco, will re-do a strpped clear-color anodized mast including cleaning all the corrosion off with an acid bath first. Re-anodizing won't make it a pitted, unshiney mast look one bit better, but it will ensure that an old but structurally decent mast lasts another 15 years without significant further corrosion.
When you compare the final cost of re-anodizing vs. repainting with 2-part LPU(Linear Aliphatic Polyurethane) (both will get you another 15-20 years out of a mast in a salt water environment), anodizing is cheaper. But if cosmetics are a concern, painting wins hands down.
The rest of the costs of re-anodizing are the same as painting (removal and reinstallation of hardware, rigging, etc.) except for a couple of differences:
1. You can't re-anodize without completely removing everything and re-installing it. The acid bath that must be done before re-anodization eats SS. You can paint over riveted fittings. (The pre-wash and chromate-wash done before repainting is not done in a tank, it’s scrubbed on and then hosed off, and you can leave some fittings on the mast.)
Repainting Notes:
For a long lasting paint job, the painter should prep with both acid and chromating agents like Alumiprep and Alodine, then use primer specifically formulated for aluminum before applying the compatible topcoat of your choice.
Or you can repaint with a roll and tip method yourself. LPU lasts longer than one-part poly paints because LPU is much harder and bonds better. But LPU and compatible primer will add some dollars to the cost, compared to using a one-part poly.
If the anodizing is gone on your mast, the cheapest way to keep you mast structurally sound is to paint it yourself. Painting the mast yourself, either with one-part or two part poly, saves money. If time is more precious to you, pay somebody else to paint it.
If your anodized mast is in good shape and doesn't grow a coat of white fuzz every 6 months, don't do anything other than wax and clean it periodically. Remove through bolts/fittings that move and re-bed with TefGel or Lanocote or BoatSeal every two-three years to prevent hole enlargement at "working surfaces"
