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Thanks Jim n Frank, I downloaded a whole lot of info last time this thread came up
but couldn’t see anything on galv n corrosion etc. So this goes in. Cheers, Hugh From:
owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of ShellyDalg@aol.com The most commonly used method is what Vance mentioned. Epoxy
paint. That's the stuff that's a two part mix and it's tough stuff. Jim K.
is a painting contractor and he can give you brand names that are available
now. I talked to a painter using epoxy paint a while back for some large
columns exposed to salt air and he said it's expected life span in that
environment was about 5 years. I know that a zinc coating uses the "sacrificial"
properties to create an oxide on the surface, preventing oxygen from reaching
the metal below. Steel, aluminum, stainless, and probably all metals react that
way ( I think.) In the jobs where I've used it, zinc rich paint exposed over long
periods to weather and sun gets a little "dusty" layer that develops
on the surface. That's the zinc oxide. We used a paint called "Zincalate" and you had to keep
stirring it so the zinc would stay in solution. It went on pretty thick and dried to a dull silver. It lasts a
long time when used on metal legs and stuff on the roof. I've seen things over
10 years old and the paint coat was still complete, although a little
"dusty" as mentioned. This is on the roof......not submerged. A friend made a small metal ladder for his sail boat and painted
it with the Zincalate. It lasted quite a few years and was often submerged in
salt water for weeks at a time. That's what interested me in that Rhino stuff. It's more a rubber
coating than a hard paint. The sales info described it as creating an
"impervious, monolithic " layer on the metal that was flexible enough
to allow the metal to flex without breaking the bond and/or leaking. If we painted over the Zincalate painted surfaces, it was
just for looks, and the color wouldn't last very long. I guess the zinc dust would form on the surface as it was oxidized
and allow the colored paint to flake off. Maintenance comes into play here. Regardless of what paint is
applied, at some point it needs repair. Whether it's caused by scratches or
just normal wear or salt water corrosion, nothin' lasts forever. Epoxy paint is the norm and it's probably the easiest to repair or
"touch up". Because we are taking our subs out and drying them daily a good
epoxy paint would probably still win out in an overall test of reliability. It's expensive to buy, and a pain to spray on, but still has a
known track record with documented results. I'll still be asking questions about that Rhino type stuff, but
for now, the epoxy is the safe bet. I think it still runs $600 for a mix of two 5 gallon buckets, part
A and part B. One nice thing though, it comes in all colors ! ( even the
dreaded YELLOW !! ) Frank D.
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