[NHCOLL-L:4154] RE: Cleaning oxidized pyrite mineral specimens

[Robyn Hodgkins]

Thank you everyone for your comments. I now have a pdf of the Waller 
paper. If anyone else is interested in reading the article, I can send 
you the file.
Thanks again!
Robyn Hodgkins

Chris Collins wrote:
> Robyn,
>
> As Simon suggests, we would tend to use the 'waller method' using 
> ammonia solution with PEG 400 as this is the more reliable method. 
>  The ethanolamine thioglycollate method (cornish and doyle, etc.) is 
> time intensive, can be inefficient and can if used  incorrectly lead 
> to further damage to the specimen.  It does remove decay products from 
> the specimen however it requires some care in use. If you use the 
> 'waller method' then ensure you also set up the measurement tube (as 
> laid out in waller's paper) as if left too long the relative humidity 
> can rise in the chamber above a critical point and you can end up with 
> further damage as the PEG 400 acts as a sorbent rather than a buffer. 
> We tend to monitor progress quite closely and remove specimens as soon 
> as the measurement system indicates that there has been complete 
> migration through the specimen.  You should check Wallers paper 
> however -  Waller, R. (1987) An experimental ammonia gas treatment 
> method for oxidised pyritic mineral specimens. ICOM  8th triennial 
> meeting Preprints Sydney 1987.
>
> Regards
>
> Chris
>
> Chris Collins
> Head of Conservation
> PCU
> Natural History Museum
> Cromwell road
> London
> SW7 5BD
>  
> Tel: 0207 942 5039
> Mobile: +44 7920007065
>
>
>
>
> On 9/1/09 10:05, "Moore, Simon" <simon.moore at hants.gov.uk> wrote:
>
>     Hi Robyn,
>
>     I always use Rob Waller's method (I think that it was his!) of
>     using ammonia vapour to neutralise the iron salts and to reduce
>     the size of the water of crystallisation molecule.  Sorry I don't
>     have the reference handy but I think it's in/ Collection Forum/ c.
>     1990.
>
>     Closed container with small beakers (100ml) half-filled with
>     PEG-400 (poly-ethylene glycol), then add about 3ml of 0.880
>     ammonium hydroxide, leave overnight.  Not used ETG as yet nor
>     heard of Super Iron Out....?
>
>     Hope that this helps but I'm sure you'll have plenty of replies!
>
>     With all good wishes,
>     Simon Moore, MIScT, FLS, ACR,
>     Senior Conservator of Natural Sciences.
>     Hampshire County Council
>     Recreation & Heritage Department,
>     Museums & Archives Service,
>     Chilcomb House, Chilcomb Lane,
>     Winchester SO23 8RD. UK.
>     Internal  8 327 6737
>     01962 826737
>     _http://www.hants.gov.uk/museum/biology_
>     <http://www.hants.gov.uk/museum/biology>
>
>
>
>     -----Original Message-----
>     From: owner-nhcoll-l at lists.yale.edu
>     [_mailto:owner-nhcoll-l at lists.yale.edu_
>     <mailto:owner-nhcoll-l at lists.yale.edu> ] On Behalf Of Robyn Hodgkins
>     Sent: 09 January 2009 00:54
>     To: NHCOLL-L at lists.yale.edu
>     Subject: [NHCOLL-L:4140] Cleaning oxidized pyrite mineral specimens
>
>     I am a UCLA chemistry graduate student helping the Natural History
>     Museum of Los Angeles County Mineral Science department. They have
>     several minerals containing iron sulfides that have become brown
>     in color. The corrosion has not been completely identified, but we
>     believe it is mainly oxidized pyrite corrosion. The Museum is
>     interested in cleaning these minerals. I have found literature
>     about using ethanolamine thioglycollate to clean. Has anyone used
>     this or has an opinion of how this would compare to Super Iron
>     Out? thanks!
>
>     Robyn Hodgkins
>     Graduate Student
>     Garrell Group
>     UCLA Chemistry and Biochemistry
>     hodgkins at chem.ucla.edu
>     310-206-9434
>
>
>
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