Coating for inside NEW aluminum holding tank

[Scout 30]

Originally Posted by Rowglide

Well her is the plan...
I will be getting a fuel tank sealer from Aircraft Spruce and "sloshing" the inside very carefully, (I can see throughout the tank throught the fitting / level gauge holes)
Then I will follow up with a glass / epoxy wrap over the entire tank. The only place I cannot really cover is the threads on the fitting hole, but they are really heavy aluminum (Over 3/8" thick) so I won't lose too much sleep there, may use tank sealer as thread sealer when installing fittings.
And then we will start the clock. Tanks is a breeze to install / remove so if it has to go at some time in the 2-3 year future, it'll only take a few hours to deal with it.
I'll report back with results, but don't stay up waiting, it could be quite a while.
Jim

If you glass the tank I doubt you'll ever have to replace it.

[estarzinger]

Two things:

(1) coating 'clean' aluminum . . . . to have a solid bond to aluminum you pretty much need to degrease, abrade and then 'prime' with one of the aluminum specific products ( like the aluminprep & alodine combo). This is because 'clean' aluminum usually has both some sort of greasy or wax from the foundry, and also oxidization, and leaving either will cause bonding problems. This is an issue with pretty much any 'thin' coating, less of an issue with 'thick' (the 5200 thickness and thicker) coatings that can remain intact with bubbles and poor bonding underneath. Note: it is possible to acid etch rather than abrade but is trickier, especially if you can not closely inspect it.

I have a lot of experience with aluminum coating.

(2) Making relatively thin fiberglass layers actually totally fluid impermeable is more difficult than you might think - the glass weave is obviously not impermeable so you are depending on the resin having no pin-holes and developing no cracks, when the aluminum will be expanding and contracting with thermal changes. It can be done . . . but is trickier than you might expect and (usually) requires more layers of glass. The guys in the C-Class learned this about their carbon wing skins and superthin carbon laminates (the core would soak pretty quickly because it was often not entirely vapor tight).

Really . . . if you are going to this effort . . . get a plastic tank and be done with it.

[johnnymaddox]

Don't be $$ stupid. Get a poly tank now.

[GordMay]

Greetings and welcome aboard the CF, Johnny M.

[Scout 30]

I've actually glassed an aluminum water tank during my refit & it made sense to me because it was in good shape & I already had the plenty of materials. That being said, even though it would probably work, I'd have to fall into the buy a new tank camp. Aluminum holding tanks just don't make sense & it's a boat so if something can go wrong it will.