Glass beads

Helen Slade <sladehf [at] yahoo__co__uk> writes

>I am researching a number of late 19th century black dyed silk
>textiles which have degrading (formation of white crystals,
>crizzling and weeping) black glass beads. ...
>...
>From the published literature the degradation of black glass beads
>on black textiles form the late 19th century seems to be quite
>common, is this just a coincidence or have other people also
>observed more glass decay on black textiles than other colours?

I think you will find that it is the color of the bead, more so,
than the color of the textile, that is responsible for the bead's
instability. In general, white beads are the most stable, because
they have CaO in them. This crucial stabilizer was often removed for
the production of clear darker beads (such as red, blue, black), and
thus they are much more susceptible to moisture, and eventual
crizzling. In summary, you are most likely looking at a glass
composition problem.

Stephen Koob
Conservator
The Corning Museum of Glass
One Museum Way
Corning, NY 14830
607-974-8228
Fax: 607-974-8470


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                  Conservation DistList Instance 15:63
                  Distributed: Tuesday, March 19, 2002
                       Message Id: cdl-15-63-008
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