Question about Alodine 1201

I can't say why the recoat is giving you "better" results than the
first-time coat, but the Alodine/Iridite passivation treatment IS very
soft when it's first applied. It's never very abrasion resistant (it's
meant to be topcoated), but when it first reacts with the aluminum,
it's a watery gel. That's why the aluminum must be squeaky clean
before you treat it - water don't stick to oily stuff like
fingerprints.

Let the parts hand in the breeze for a day or two after you alodine
them, and they'll be as good as they get.

And remember, no aluminum Piper ever built, and damn few Cessnas ever
got alodined. You're gilding the lily in the first place....only the
Government (and mostly the Navy at that...) could ever afford to be
this picky about corrosion prevention.

"flybynightkarmarepair" wrote in message
oups.com...

snipped a good reply

only the
Government (and mostly the Navy at that...) could ever afford to be
this picky about corrosion prevention.

Agreed. And those steps Andrew listed are right out of Corrosion Control
School. I can still picture that 'crusty old instructor' lecturing us at
Naval Air Station Miramar in 1979. And it was basically the same during the
dozen or so times I sat through those lectures since.

Yep, the Navy is big on Corrosion Prevention. Follow those steps and you'll
have few problems.

On Wed, 05 Apr 2006 05:40:20 GMT, "gonefishn"
wrote:


"flybynightkarmarepair" wrote in message
roups.com...

snipped a good reply

only the
Government (and mostly the Navy at that...) could ever afford to be
this picky about corrosion prevention.

Agreed. And those steps Andrew listed are right out of Corrosion Control
School. I can still picture that 'crusty old instructor' lecturing us at
Naval Air Station Miramar in 1979. And it was basically the same during the
dozen or so times I sat through those lectures since.

Yep, the Navy is big on Corrosion Prevention. Follow those steps and you'll
have few problems.


between the water break test and the alodining there is sometimes a
prep wash of very dilute phosphoric acid to bite away all corrosion
followed by a distilled water rinse then the alodine.
Stealth Pilot

In article 8LIYf.23170$fQ6.1489@trnddc03,
"gonefishn" wrote:



Yep, the Navy is big on Corrosion Prevention. Follow those steps and you'll
have few problems.

I didn't know the Navy was renting out tie-downs on their carriers, for
the GA fleet. I've taken some heat for my faith in naked aluminum, but
then again I'm not planning to wash my plane in acid rain and soak it in
salt water spray on a daily basis. I'm also hoping that a good coat of
that fancy waterproof paint on the outside will help keep the inside
fairly dry.

And remember, no aluminum Piper ever built, and damn few Cessnas ever
got alodined.

This is not *exactly* correct. Every zinc chromate painted part in a
Cessna (or Beech or Piper) received iridite before painting. Paint
won't stick right without it. Part of MIL-C-5540 or whatever (I'm
rusty).

If you ordered the hideously expensive "corrosion resistance" package,
you got an extra couple hundred pounds of paint -- but no increase in
useful payload. Guess how popular THAT was?? The oil filter adapter
was treated and then clearcoated leaving it golden color (and priced
accordingly).

You don't mention how "clean" your part is. Are you taking off the
Clad coating? If so, the parts really need to remain *submerged* until
coating. Any exposure to air will instantly start oxidation and reduce
coverage quality (usually judged, as you're doing, by depth of color).

My theory is that your initial coating, utilitzing your stated process,
is merely adhering to an oxidation layer that, of course, scrubs right
off. The most of the surface was "sealed", if you will, against
further oxidation and once re-treated, responded in a more predictable
and acceptable manner. Just a guess.

Larry

larry wrote:

You don't mention how "clean" your part is. Are you taking off the
Clad coating? If so, the parts really need to remain *submerged* until
coating. Any exposure to air will instantly start oxidation and reduce
coverage quality (usually judged, as you're doing, by depth of color).

My theory is that your initial coating, utilitzing your stated process,
is merely adhering to an oxidation layer that, of course, scrubs right
off. The most of the surface was "sealed", if you will, against
further oxidation and once re-treated, responded in a more predictable
and acceptable manner. Just a guess.



Larry

Can you explain what you mean by Clad coating?