These just came through the MG-TABC list and looked really helpful, so I
thought I'd pass them on. I never considered the wet sanding technique to
avoid flash oxidation on aluminum, etc., but it sure makes sense.
I certainly agree that moat hardware store epoxies aren't worth the goo in
the tubes!. For many years we had garage customers come by our sailing
hardware store looking for JB Weld or a sub. to close pinholes in gas tanks.
By & by we switched them over to W.E.S.T. epoxy as a better product.
Basically you clean leak pinhole with whatever, then force epoxy thru hole
(enlarging if necessary). This creates a "mushroom" head in tank that seems
to produce a reliable fix. The same technique can be used to patch pinholes
in air toys, rafts, etc. Only instead of using epoxy use 3M 5200 adhesive
sealant. Force it thru to make a mushroom head on inside of vinyl & you are
back in business.
When bonding a hard to bond metal , e.g. alum. to whatever, there is an easy
technique. Just "wet" sand the alum with catalyzed epoxy & emery paper.
Sanding alum. Bnz. Copper, & other hard to bond metals to bright metal
doesn't really get the metal "bondable" clean . They may look clean, but
after cleaning they will still oxidize enough to result in an unreliable
bond. Wet sanding with epoxy insures that surface is covered with epoxy
film, isn't exposed to air & thus won't oxidize.
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