Ok, I just have to weigh in here.

First, I know that many people swear by Duco, especially those who
mend archaeological sherds, but Duco has been long in disfavor in
professional conservation. It does not age well and will become
brittle and lose strength over a time span of a few years. I have seen
vessels collapsed from Duco adhesive failure and once even saw one
break apart when being picked up. Not good. Polyvinyl Acetate (PVA)
most recognizably known as white glue (Elmers, for example), used to
be used a lot in conservation but it's applications have eroded due to
its soluability in water and also the fact that it can contain acids.

There are an array of adhesives and approaches to mending ceramics but
it entirely depends on the nature of the body, the vessel type, and
where any losses are located. Getting close fitting tight joins is
essential as you mend. Often historic ceramics have an internal stress
within them from firing that releases when cracked or broken and thus
many vessels might be "sprung" - this presents a real challenge to
mending a vessel and you should not attempt to push in or place sherds
back under stress to achieve alignment. And then there is a whole
approach to filling losses and cracks on vessels as well.

I would say that if there pieces are archaeological then leave them
alone unless there is a compelling reason to mend the sherds (study
collections, exhibits). And if there are cross-mends with the
fragments between features on the site you'll need to record the
numbers on each sherd with a photo or sketch before you mend. If this
is an historic ceramic that has been dropped and broken then just know
that once mended it will never be perfect - its a rare occurance but
occaisionally you'll get a broken ceramic where the fragments align
and register perfecftly.

There is also the health and safety issue. The majority of the good
adhesives contain solvents and can have significant health effects.
You always need to mend where there is adequate ventillation and
really good light.

If you have never mended before of have only done this a time or two -
please practice on flea market or thrift store pieces first before
diving into an aracheological or historic ceramics.

Cheers!
Dave

David Harvey
Conservator
Los Angeles, California


On 8/16/06, =?windows-1252?Q?Elizabeth?=
<[log in to unmask]> wrote:
> In my lab we use polyvinyl acetate glue [
> http://www.lightimpressionsdirect.com/servlet/OnlineShopping?
> DSP=50000&PCR=30000:120000:122000:122200:122201&IID=2744 ].
>   In another
> lab I worked at, they reconstructed prehistoric ceramics with DUCO
> ($.98/tube at WalMart).  Both glues are able to be removed with nailpolis
> h
> remover.  DUCO worked wonders, but I constantly questioned it's integrety
> .
>
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