[meteorite-list] Experiment Update #1

From: Norm Lehrman <nlehrman_at_meteoritecentral.com>
Date: Fri Mar 3 00:40:22 2006
Message-ID: <20060303054019.93454.qmail_at_web81009.mail.mud.yahoo.com>

G?ran & all,

I don't understand the chemistry involved, but I have
personally used a concentrated sodium hydroxide bath
to remove rust from very rusty Campos. It took weeks,
but scales of rust just kept detaching untill the
bottom of the pail was a centimeter deep in rust
flakes. I did do a final treatment with a wire brush,
 but ended with a beautiful metallic specimen. This
treatment wasn't just a rust stopper. It removed rust
in large quantities. The solution didn't discolor as
if iron was being dissolved. Flakes just popped off
and fell to the bottom.

Cheers,
Norm
http://tektitesource.com

--- G?ran Axelsson <axelsson_at_acc.umu.se> wrote:

> This is not a rust cleaner treatment, it is a rust
> stopper treatment.
>
> To remove the rust you have to use more traditional
> methods, like polishing.
>
> Acidic solutions with a low Ph makes it easier to
> dissolv the iron
> hydroxides in rust but at the same time the iron
> will be unprotected
> against oxidation. Basic solutions with a high Ph
> stops the iron
> hydroxides to dissolv but protects the iron against
> oxidation by
> passivation, it becomes chemically inert.
>
> The idea behind the hydroxide solution is to protect
> the iron while
> chloride ions are leached out of the meteorite.
>
> I would recommend small volumes in the bath, maybe
> twice the volume of
> the meteorite but at least covering it, combined
> with numerous
> replacement of the solution. In the beginning it
> should be closer
> between the changes of the solution as it faster
> gets contaminated. When
> the chlorine levels in the meteorite and the
> solution is in balance it
> doesn't help to let it lie longer.
>
> Archeologists sometimes uses ordinary tapwater in
> the initial bath but
> at the end they use deionised or distilled water.
>
> And whatever you do, don't use chlorinated water,
> that could make it
> rust even faster.
>
> /G?ran
>
> tracy latimer wrote:
>
> > About 10 days ago I dunked my poor Fredericksburg
> in what I hoped
> > would be a rust removal bath of half Liquid Drano
> and half anhydrous
> > alcohol. Since then, I have swirled it about at
> least once a day, and
> > some of the rust has come off, but not all. The
> bath is lightly
> > tinged with brown and there is a fine peppering of
> rust flakes on the
> > bottom of the glass jar. I will give it another
> week or so, but if
> > there is not a significant change in the quantity
> of rust in
> > suspension rather than on my meteorite, Freddy
> will be taken out of
> > the bath and more old fashioned methods of getting
> rid of rust will be
> > regretfully employed.
> >
> > Watch this space for more fast-breaking news!
> > Tracy Latimer
> >
> >
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Received on Fri 03 Mar 2006 12:40:19 AM PST