Thom-
<br>I have seen multiple painted masts, Mystere I think even had them sort of standard at one time and many monohulls utilize painted masts/booms. Most aluminum fittings/extrusions that are specific to marine applications come with an anodized coating from the maker- Anodizing is simply a chemical process where the metal is actually essentially oxidized in an environment where a uniform coating ends up on the surface of the metal. Common "colors" that result are dull (or whitish- the most common), gold and black depending on the final aluminum oxide produced. I would suspect your SC 20 has the typical anodized coating, scratches in the coating appear more "silver" due to the removal of the coating. A natural oxide layer will develop very quickly over raw aluminum (this is what Phill was referring to in his post as the "discoloration"). Anywhere the anodizing is "lost" the aluminum will begin to "oxidize" on it's own, including corrosion (this is why your boom and mast often corrode only around the rivets, holes, and mast foot and base). If you keep that SC in fresh water shouldn't be an issue, if you get it in a more corrosive environment, especially where there is "movement" etc. (ie. not just a surface blemish but the aforementioned rivet holes, etc. that get "worked" and stay wet, especially if in contact with a dissimilar metal- like stainless steel) you can get severe corrosion and failure of the piece. This is why it's important to try to seal all these areas w/ silicone, anti-sieze/anti-corrosion materials initially and periodically inspect/reseal.
<br>Another reason to stay in Big D ;-)
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<br>Kirt<br><br>Kirt Simmons
<br>Taipan #159, "A" cat US 48