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[oletrucks] Further adventures in rust removal

To: virtualvairs@corvair.org, oletrucks@autox.team.net,
Subject: [oletrucks] Further adventures in rust removal
From: mark@noakes.com
Date: Mon, 27 Oct 2003 19:24:25 -0800 (PST)
After my prior post on electrolytic rust removal, I got a few more suggestions 
and a
couple of challenges as to how safe this technique is from various lists and so 
did some
more checking with the following comments.  The most important thing to note is 
I'm just
a hobbyist like you guys exploring what my options are and reporting results; 
I'm not a
professional in this field.  Treat the info accordingly.

1--White Vinegar can also be used to clean some rust; I haven't tried this one 
others have reported that it works.  It shouldn't have any negative effects per 

2--A more thorough treatise on electrolytic de-rusting can be found at:


For some reason, I couldn't get the whole document to print though.  If you 
intend to
try this technique, read that whole article.

3--There is one major concern with electrolytic cleaning and that is hydrogen
embrittlement.  ShopNotes (my experiment reference) didn't mention it at all 
(but in all
fairness, their interest was in cleaning tools), but the site in item 2 does 
even though
they treat it mundanely.  After a comment from one email that I had ruined my 
arms, discussing this issue with a PhD metallurgist specializing in hydrogen
embrittlement and a little further study, I came up with the following:

* The issues are embrittlement of the metal due to hydrogen takeup and possible 
cracks from hydrogen buildup in the material around internal defects in the 
Hardened steel tends to be susceptible; softer material is not usually.

* Hydrogen embrittlement is temporary.  it will go away on its own after a few 
weeks or
can be removed by heating the treated object to about 160C for about 14 hours.

* Obviously the stress cracking that may occur during hydrogen embrittlement 
would be
permanent and could lead to catastrophic failure of the object, hence the 
reason for not
using this technique on safety-related items.

* Sodium bicarbonate electrolytic cleaning is mild and would not normally be a 
on any steel for an hour or so.  However the effect is time, material, and 
dependent; at the very least, hardened steels should not be treated for extended

* Final suggestion is don't use this technique on hardened steel such as 
springs and
restrict use on any high strength steel components...such as steering arms 
suspension components, etc.  Stick to good old sandblasting for hardened steel. 
electrolytic technique is fine for non structural items or anything that is not 
strength steel.  Of course,  my interest in this technique was that I didn't 
have a sand
blaster, and I have had parts damaged by over zealous commercial blasters that 
I have
taken parts to. 

*  Since I had already treated my steering arms, one suggestion to determine 
was to use a file on a safe portion of the object.  If the file can readily 
material, then the object is relatively soft and was probably not affected.  
The file
cut into the one I tried fairly easily...shouldn't these be pretty hard?  I'll 
see if I can get them tested at the local university metallurgy lab to see if 
they are
ok.  The only way to be sure is not to electrolytically treat critical parts.

4--I tried another experiment, this time with the center mount tail light 
assembly from
a 50s era Suburban tailgate; these are very rare and I have managed to collect 
complete units plus most parts for a third. This particular unit had heavy rust 
so much so that I couldn't even begin to work the nuts on the internal screw 
studs to
take things apart to restore it.  Sandblasting would have ruined it.  I put it 
in the
bath for about 12 hours and it reduced the rust about 80%,  to the point where 
I can
work with the internal parts.  I'll disassemble it as much as possible and and 
then dunk
the subassemblies that need it again.  There are no structural issues with this 
part so
the dunk time is not an issue.  This is the kind of cleaning task for which the
electrolytic technique is perfect.
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959

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