Sarah-

These are the issues that you should consider when thinking about mending a
ceramic object or artifact:

First - Do you have all the pieces? If not, will the losses affect the
structural integrity of the object? In order to acertain this you will need to do
the "puzzle work" (e.g. matching the fragments onto the body) before attempting
to use adhesive.

Many ceramics have an inherent internal tension as a result of firing and
this is released as a result of breakage - so they can be "sprung" and the
ceramic form no longer lines up when the fragments are mended.

Second - What kind of ware is it?  Is a soft-bodied earthenware? A dense
heavy stoneware? Or a porcelain? Is the object tall - like a vase? Or is a more
horizontally oriented object like a plate? This will affect the sort of adhesive
and approach to mending that should be taken.

You've got to be especially aware of fragile ceramics such as the very
low-fired crumbly ethnographic wares or the ones with fragile surfaces like
delftwares or majolica (tin-glazed earthenwares).

Third - the "safe" adhesives that are used in conservation are not available
at the hardware store. I am sure that many people on this list have
encountered examples of ceramics mended 20 to 30 years ago that have either come apart
or the adhesives have discolored (the "Duco" phenomenon). The adhesives in use
now have been tested for longevity and stability - though you must always be
aware of the glass transition temperature. I have heard of instances of pieces
coming apart under the heat of photography lamps.

If you do acquire some Acryloid B-72 (Paraloid B-72 in the UK) at the
appropriate strength for mending you are still not "Safe". These are solvent-based
adhesives that take time for the solvent to evaporate and for the adhesive to
cure at full-strength. You will require excellent ventilation to do this -
especially in a work space shared with other people. You've got to meet OSHA
standards in this regard.

Cheers!
Dave

David Harvey
Artifacts
2930 South Birch Street
Denver, CO  80222
303-300-5257
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