Desalination

Laura Jimenez <ljimenho [at] banrep__gov__co> writes

>We need to desalinate archeological pottery (Tairona-Colombia) and
>the objects have black pigments on the entire surface or a black
>finish related to its technology; nevertheless this is soluble in
>water.
>
>We are thinking of protecting it by consolidating with paraloid B72
>at a really low concentration ...

I don't think consolidating with Paraloid B72 is a wise move, since
(from what I have experienced, that also comes to an agreement with
its chemical composition) when this material comes in contact with
water it hydrolyzes and forms a white cloudy film on the surface. It
is possible to remove it later on with acetone or a similar
properties solvent but it is very likely to remove the paint as
well.

I would suggest to consolidate the surface with a thin layer of
cellulose ether such as methyl cellulose, or similar, and perform
the desalination from the inner surface of the pot (assuming that
can be reached) with a poultice saturated in de-ionized water.
Alternatively you can use cyclododecane as a consolidant, which is a
volatile binder, either by poulticing or if you think its safe by
immersion in de-ionized water.

A quick reference on cellulose ethers you can find in Horie's
'Materials for Conservation'. Another book is the 'Evaluation of
Cellulose Ethers for Conservation' by the Getty Conservation
Institute, 1990

    <URL:http://www.getty.edu/
        conservation/publications/pdf_publications/ethers.pdf>

Of course the references on the subject are numerous.

On the use of cyclododecane have a look at

    Vanessa Muros and John Hirx
    "The Use of Cyclododecane as a Temporary Barrier for
    Water-Sensitive ink on Archaeological Ceramics During
    Desalination"

        <URL:http://cool.conservation-us.org/
            jaic/articles/jaic43-01-006.html>

    **** Moderator's comments: The above URL has been wrapped for
    email. There should be no newline.

Konstantina Tsatsouli
BSc (Hons) Archaeological Conservation
MSc Conservation
Enou 1, Nea Ionia, Volos
T.K. 38446, Greece


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                  Conservation DistList Instance 25:6
                 Distributed: Wednesday, July 13, 2011
                        Message Id: cdl-25-6-001
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