Smutt is the dark corrosion, haven't found a descriptive word for the white stuff. [Skudge?]
The dark matter is said to come from the chemical alloys Cu, Si, Zn, Fe, Mn. Mg used in extrusions. The white stuff?? Isn't bauxite white?
Looking at TonyG's mast, he hasn't got smutt.
Looking in on commanderpete's photos, one close up shows dark spots on the spars that might be smutt.
All over the stick in my possession, top to bottom, is a double layer of dark and light. An equal amount of deeper dark corrosion and a less corroded top. It is, with the 5" Makita ocillator, very hard to get into the 2 micron deeper stuff using aliminum oxide sanding disks to remove the dark aluminum oxide.
Knowledge knot knowitalls, including myself, always point out (ad nauseum) that you don't paint a mast because aluminum makes its own corrosion protection by forming oxide on the surface.
While this is true, it also is a bunch of useless BS. Anybody who looks at the mast I'm attempting to restore can instantly see that in the years it spent wired to ltlgull in a saltwater environment the aluminum did a real lousey job of protecting itself from corrosion. So this knot on the end of a line of BS is meaningless. And many unprotected masts turn up with the same problem.
It is not true that a mast protects itself with an oxide coating. The oxide anodizing it once had, if it did, also did not keep the spar from serrious corrosion.
So I'm looking for something that might dissolve the ingrained material. We are talking about oxide here that is in the same family as sapphires and rubys - it's next to diamonds on the Moh scale...but about 5 times less hard. All in all, Aluminum oxide is pretty hard.
So I thought that before sanding the dark matter should be removed, here's the short list of possibilities:
lemon, lemon and salt crystals, white vinegar, cream of tarter, baking soda, toothpaste (Crest), Hershey's chocolate [NONE OF THESE WORK]
- then there's Oxalic acid, Falseteeth soak, Flitz, NeverDull, toilet bowl cleaner, low PH drain opener, TSP, sodium hydroxide (lye, caustic soda), Penetrol, Galium and distilled H2O [none tried yet]
-then ferric sulphate, sulfuric acid, ammonium bifluoride, hydrofluric acid, phosphoric acid, methylene cloride, chromic acid and, of course, nitric acid. Nitric acid dissolves all metals. [Rediculous]
What would you do?
So many toxic choices, so little time to try them out.
I think my problem here is that aluminum is considered a porus metal,
so I don't want to have little nasty wet molecules of alkali or acid lurking deep in molecular crevises only to show up 6 coats later in the finals... just from a rediculous caustic cleaning episode.
And still in line before I get to any epoxy primer, there is the degreaser wash, the Alumiprep etch wash and the Alodine conversion wash. Still confused as to what self etching or non-self epoxy primer to use when and if or
befor (after?) the zinc chromate, strontium chromate, zinc phosphate, zinc oxide epoxy primer time arrives.
Most of those primers only come in 2-part gallons at $150 each. If ordered on line HazMat S&H gets a stiff surcharge.
I've heard that donkey urine is pretty strong...
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