[meteorite-list] how do you get off desert varnish from a oriented stone?

From: Pict <pict_at_meteoritecentral.com>
Date: Tue, 11 Dec 2012 17:02:34 -0600
Message-ID: <CCED12F2.D9DB%pict_at_pict.co.uk>

If it is caliche (carbonate buildup) then mild acid should dissolve it.
Perhaps an aqueous solution of 5% Hydrogen Chloride solution (HCl
available as muriatic acid in concentrations around 35% from hardware
stores - use eye and hand protection and good ventilation. Add acid to
water to dilute not vice versa). Try a small spot of acid on the surface
first. If it is going to do anything useful you will observe
effervescence. Downside is that the acid will also attack any free iron
but provided the acid is weak any carbonate should be dissolved away much
quicker. Once any application of acid is complete the stone will need to
be thoroughly rinsed and dried. Hcl is a gas at normal temperatures so
should evaporate away with the water when it dries. I wouldn't try this
with anything I was extremely fond of. Ideally you have another less
precious stone from the same area with the same surface deposit that can
be experimented on.

Regards,
John


On 11/12/2012 16:30, "bill kies" <parkforestmet at hotmail.com> wrote:

>
>Desert varnish in itself shouldn't obscure flow lines. He must mean
>caliche.
>
>----------------------------------------
>> Date: Tue, 11 Dec 2012 10:57:34 -0600
>> From: chicagosteve1954 at gmail.com
>> To: Meteorite-list at meteoritecentral.com
>> Subject: [meteorite-list] how do you get off desert varnish from a
>>oriented stone?
>>
>> Hi list. I have a real nice 31 gram oriented stone that has desert
>> varnish on one side. It has very nice flow lines under it that I would
>> like to see more of. Can someone please tell me how to that varnish
>> off. Thanks and have a great day.
>>
>> --
>> Steve R. Anold, chicago, ill.
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Received on Tue 11 Dec 2012 06:02:34 PM PST