In haste,
it sounds as though you have managed to collect a calcareous deposit via
percolation of seawater into the voids in the ceramic and on drying it has
had the pores blocked, probably via concretion formation, and so it has
incredible internal surface pressure and volume expansion on
crystallization and hence kabooomie!
I hope that this helps, rather than confuses.
Yours aye
Ian
At 09:37 18/01/2001 +0000, you wrote:
>Kathy Hall wrote:
>
>> Hi all,
>>
>> We have an interesting ceramic phenomenon, and were wondering if anyone has
>> seen anything similar.
>>
>> A pithos raised intact from a marine site where it had spent the past 3000+
>> years was broken in an accident in the Bodrum Museum. The ceramic walls are
>> on average at least 2cm thick and the fabric is fairly high fired, dense
>> and non-porous.
>>
>> Looking at the break edges, running parallel to the surfaces, roughly in
>> the middle of each sherd is an almost continuous layer of white, opaque
>> mineral deposit approx 1mm thick. A sample of this deposit reacts strongly
>> with dilute HCl.
>>
>> The deposit has caused many of the sherds to delaminate into separate
>> exterior and interior surface fragments.
>>
>> My question is, has anyone seen such a phenomenon before in a ceramic?
>> What would you ascribe it to?
>> We are wondering about manufacturing processes or factors relating to
>> burial and recovery.
>>
>> Apologies for cross posting,
>>
>> Kathy Hall
>>
>> Conservator
>> Institute of Nautical Archaeology
>> Bodrum, Turkey.
>
>--
>
>_____________________
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>Centre for Environmental Resource Management
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