Alodisation

[L.Pi...@univ-mulhouse.fr]

I am a chemist but I have never manege to protect correctly Aluminium parts.
None of my mixtures have maneged to have the results offerd bu commercial
alodisation products. I have herd about something like "chromic treatment"
Dose anybody knows what it is?
Dose any body knows what an alodisation process is (chemicaly?)

Leon Pikros
France

[John G Wright]

I assume "alodisation" is a misspelt anodisation - the creation of a thicker
layer of Al2O3 than normal to totally seal off the metal from the atmosphere
and prevent the otherwise very reactive aluminium from oxidisation.

If I remember correctly chromic treatment is immersion in a bath of chromic
acid, a very powerful and corrosive substance, which causes rapid oxidisation.
of the metal surface. Chromic acid (Cr2O3 in sulphuric acid) also eats human
flesh rather efficiently. Hence it's not recommended for casual use by
inexperienced persons.

John G Wright, 742.

[John Giddy]

John G Wright wrote:
>
> I assume "alodisation" is a misspelt anodisation -

<<snip>>

No, "Alodising" is a commercial process using a solution which
is brushed over the aluminium part (or it is dipped into the
solution). It does not use an electrolytic process to enhance
the thickness of the oxide, as is done in anodising, so the
protective layer is not very thick. It is usually used
as a pre-treatment before painting.
I don't know the chemistry of the process, so can't help
with how to do it. I believe it is used in the
aviation industry, so someone else may have more
accurate information, including where to get the stuff.
John G.

[F.L. Whiteley]

Dupont alodining process consists of two parts 225S(mild acid) and
226S(unknown chromating composition, part chromic acid at least). It is
not for sale to the general public and use is for trained personnel.
Alodine is a trademark of Amchem. There is an interesting perspective at
http://xre22.brooks.af.mil/608.htm

Frank Whiteley
Colorado Soaring Association

John Giddy <jgi...@melbpc.org.au> wrote in article
<33A87D...@melbpc.org.au>...

[F.L. Whiteley]

More is found at

http://www.eaa1000.av.org/technicl/alodine/alodine.htm

FLW

F.L. Whiteley <gre...@greeleynet.com> wrote in article
<01bc7d3a$1c15d7e0$83f292d0@greeley>...