Adhesive for crystal

Kathryn T. Kallmes <kallmes [at] ohmaha__inetworld__net> writes

>What is the best adhesive to use in repairing crystal?

It is not clear whether "crystal" refers to "rock crystal" or "lead
crystal", but in either case you probably want to use one of the
finer epoxies, either Epotek, Hxtal, or Fynebond.  The Refractive
Index of rock crystal is 1.54, which is at the lower end of the RI's
of the epoxies, but they will still be a good match.  Norman Tennent
lists the Norland Optical adhesives (UV-curing) down at this lower
RI, but I would still recommend the epoxies.  Lead crystal glasses
have RI's in the 1.55-1-57, which fall right in the middle of the
RI's of the epoxies.  (See Tennent, N.H., and Townsend, J.H., 'The
significance of the refractive index of adhesives for glass repair',
in Adhesives and Consolidants, Contributions to the Paris Congress,
IIC 1984, pp. 205-212.)

An acrylic resin, such as Acryloid B-72, would work, but would give
you a visually less satisfying result, owing to the bubbles left in
the join from evaporating solvent. Since the epoxies do not require
a solvent, and the RI is a better match, you can obtain an almost
invisible join.

Other factors to consider: The epoxies are extremely strong, and
will yellow over time. They can be removed, however, by swelling
with methylene chloride.

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


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                  Conservation DistList Instance 13:40
                 Distributed: Friday, January 14, 2000
                       Message Id: cdl-13-40-004
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