On Sat, 06 Sep 2003 02:53:32 GMT, "Flightdeck"
wrote:

We have a similar spec. (in the Aerospace Industry) that
says prime x hours after alodine or else. My guess is the impetus
for applying a quality primer asap over freshly applied alodine is the
alodined surface is very susceptible to scratches / blemishes in
handling the part (the alodined surface is very soft). In fact, if
it weren't for the susceptibility to scratches, damage, etc., a
properly cleaned, alodined aluminum surface has fantastic
anti-corrosion properties. It's just that the bare conversion coating
doesn't hold up well to abuse/wear....

Bela P. Havasreti

Hi,

Do you happen to remember the source of the article? This has never been
part of a protocol that I have worked under when painting aluminum after
using Alodine 1201. However, it has been so long since I have actually
"read the instructions" I dug out the paperwork for both Alodine and the
numerous primers I have used over the Alodine. The only time sensitive
reference I could find was related to the time between the aluminum
cleaning/etch and the application of the Alodine. None of the non-etching
primer product application sheets had a time reference to the delay since
Alodining - Except for the statement, "The primer should be applied as soon
as possible after the application of a conversion coatings such as Alodine.
" But, this was in the same paragraph that talked about the necessity for an
absolutely clean and properly prepared surface. Personally, I have never
had a problem with primer adhesion due to a time delay.

In the article you read, it could be that there was a concern for surface
contamination or coating damage after the application of the Alodine.
Alodine produces a very thin conversion coating and any agressive efforts to
clean a previously Alodined part will remove some or all of the coating. If
we need to re-clean an Alodined part (someone touched the surface or edges
with bare fingers after the final water rinse has dried) we use only MEK on
a very soft cotton cloth.

Maybe I have been lucky.

J








"Pat Yearick" wrote in message
. com...
I read an article that said that you should paint a part before four
hours (max) of applying Alodine.

What do you do if you don't get it done in that time? Wash it off,
sand it off, paint anyways?

Thanks