Susan and other Histarchers,

Could it be salt water getting into the sherd? When salt water dries, 
the formation of crystals can cause ceramics to spall/split.

Nearly all of my white earthen ware ceramics from a coastal Maine site 
(c. 1800) were split. I think it was due to a combination of freeze/thaw 
cycles and salt water. At this point most are from relatively close to 
the surface.

Ben Carter

On 11/10/2010 6:18 PM, Susan Walter wrote:
> Hmmm, the site is in San Diego County...
>
> ----- Original Message ----- From: "Mark Branstner" 
> <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Wednesday, November 10, 2010 11:40 AM
> Subject: Re: split ceramics
>
>
>> Susan,
>>
>> I don't know what part of the country that you're working in, but
>> "frost spalling" is a relatively common phenomenon ...
>>
>> Essentially, moisture gets into the porous fabric of the pottery and
>> it splits the pottery when it freezes during the winter.  It
>> certainly does not happen all the time, but it does occur with some
>> regularity.  Sometimes just the glaze spalls off the fabric, but the
>> fabric itself can split.
>>
>> Mark
>>
>>
>>> Nov. 10, 2010
>>>
>>> Hello all,
>>>
>>> I have a site with several sherds of transferware that are split so
>>> that there is a transferware / glazed surface on one side and the
>>> paste interior on the other side.
>>>
>>> This makes them about 1/8 inch thick.  They tend to be about 1 inch
>>> long, and about 3/4 inch wide.
>>>
>>> The edges are not shaped; in "plan" view the pieces are
>>> miscellaneously trapezoidal.
>>>
>>> In appearance they somewhat remind me of porcelain pin
>>> trays/childrens toy tea trays that are decorated and glazed on the
>>> top and bisque on the bottom, except these transfer pieces are not
>>> smoothly finished on the bottom ("bisque") like the porcelain items
>>> are.
>>>
>>> I do not think these were made intentionally.
>>>
>>> I've not seen so many of these at one site before.  Has anyone
>>> knowledge of what did this?
>>>
>>> Thanks every one,
>>>
>>> S. Walter
>>
>>
>> -- 
>>
>> Mark C. Branstner, RPA
>> Historic Archaeologist
>>
>> Illinois State Archaeological Survey
>> Institute of Natural Resource Sustainability
>> University of Illinois at Urbana-Champaign
>> 209 Nuclear Physics Lab, MC-571
>> 23 East Stadium Drive
>> Champaign, IL 61820
>>
>> Phone: 217.244.0892
>> Fax: 217.244.7458
>> Cell: 517.927.4556
>> [log in to unmask]
>>
>>
>> When you think of that perfect retort five minutes after the
>> conversation is over -  that's when you're:
>>
>>  "... bursting with the belated eloquence of the inarticulate ..."
>>
>> Edith Wharton in the "The Age of Innocence"
>
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