Thanks for the information Graham, I especially appreciated the link to th e
galvanic process.
Jerry Flaherty
----- Original Message -----
From: "ensoramanda" <[EMAIL PROTECTED]>
To: "dean bessey" <[EMAIL PROTECTED]>;
<[email protected]>; <[EMAIL PROTECTED]>;
<[EMAIL PROTECTED]>
Sent: Tuesday, October 23, 2007 7:17 PM
Subject: [meteorite-list] Cleaning a 13kg "Bessey Spec"! :-)
Hi Dean, all...
Many thanks to all those who replied to me with tips on cleaning caliche
from meteorites and to you, Dean, for my 13kg "spec" which has become the
subject of several hours of careful cleaning.
The monster before cleaning, below...showed great potential even though
quite weathered....but most was hidden under 2/3rds caliche. The exposed
area had some fusion crust but most had been scoured away and polished by
the sand and wind. Lovely thumbprints though.
http://i117.photobucket.com/albums/o43/LaburnumStudio/13kgNWA/DSCN0009.jpg
http://i117.photobucket.com/albums/o43/LaburnumStudio/13kgNWA/DSCN0008.jpg
http://i117.photobucket.com/albums/o43/LaburnumStudio/13kgNWA/DSCN0007.jpg
http://i117.photobucket.com/albums/o43/LaburnumStudio/13kgNWA/2080_1.jpg
Looking closely when it arrived I could see tantalizing glimpses of what
appeared to be flow lines, lips and bubbly fusion crust in some thinner
areas of caliche. So I decided to brave it and set to work cleaning.
Because of the delicate features I wanted to preserve I did almost no
mechanical scraping or wire brushing but used brick cleaner (dilute HCl
acid) and small stiff paint brushes to gradually dissolve the caliche and
I was surprised how well it worked.
I regularly washed the acid away with deionised water and bicarbonate of
soda to try and stop too much acid penetrating too deep. After a while
some of the well preserved fusion crust was revealed. Some areas almost
look fresh with bubbling and very thick accumulation. Remnants of flow
lines and roll over lips too....
I did try some rust removers on some of the rust spots too....but they
seem very difficult to remove...nothing really worked ...infact I had to
reuse the brick cleaner to remove residues that were left.
Once I was satisfied I could reveal no more without damaging the meteorite
I decided to make sure I had removed all the acid and chlorides left which
might cause future problems and used the galvanic method described here...
http://www.alaska.net/~meteor/Galvanic.pdf
I used the less agressive washing soda method in a large bucket with
plenty of perforated aluminium foil wrapped around the meteorite to allow
circulation and electrolosys to work overnight. I did this twice until
the bubbling reaction stopped.
Finally I rinsed well again with plenty of dionised water and left the
meteorite to dry thoroughly in the oven on a low heat for a couple of
nights. It remains to see how stable this meteorite is over time...we will
see.
I know many collectors like to leave pieces as found without tampering
with their looks....but in this case I felt that the exercise was worth
it. There was so much hidden away under all that caliche.
Take a look here and see what you think of the cleaned up result!
http://i117.photobucket.com/albums/o43/LaburnumStudio/13kgNWA/IMG_4198b.jpg
http://i117.photobucket.com/albums/o43/LaburnumStudio/13kgNWA/IMG_4170b.jpg
http://i117.photobucket.com/albums/o43/LaburnumStudio/13kgNWA/IMG_4177b.jpg
http://i117.photobucket.com/albums/o43/LaburnumStudio/13kgNWA/IMG_4189b.jpg
http://i117.photobucket.com/albums/o43/LaburnumStudio/13kgNWA/IMG_4195b.jpg
http://i117.photobucket.com/albums/o43/LaburnumStudio/13kgNWA/IMG_4194a.jpg
http://i117.photobucket.com/albums/o43/LaburnumStudio/13kgNWA/IMG_4199b.jpg
Please be aware that these methods are probably risky and who knows what
the long term effects may be...so I would advise caution to anyone trying
this with acids etc.(The troilite and probably other surface minerals in
the meteorite will obviously be changed to some degree, as evidenced by
some sulphurous smells during cleaning) Different meteorites may react in
different ways and some deposits may not dissolve away. So please don't
try this on something you may regret ruining. I would not like to be held
responsible for that. I was more interested in the aesthetic external
qualities in this case...so was willing to take the risk....although I may
polish a window in an uncrusted area next...just out of curiosity! :-)
Regards
Graham Ensor.
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