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Subject: Water glass

Water glass

From: Stephen Koob <koobsp>
Date: Wednesday, May 16, 2001
Barbara Appelbaum <aandh [at] mindspring__com>

>I got a question from a colleague not on the list about water glass:
>was it commonly used in restoration, particularly as a coating on
>gilding?  What is its solubility and is there some way to recognize

Waterglass, also known as "sodium silicate" (Na2SiO3) was commonly
used as an adhesive, and was recommended as such for the repair of
glass in the 19th-20th centuries, e.g. Gaudens, P. and Jackson, A.
"How to mend china and bric-a-brac", Boston: Charles Branford Co.,
1953, p. 105. Waterglass was also used as a binder and flocculant
for ceramic glazes, an additive for concrete, manufacturing paper,
and in fireproofing textiles. The proportions of silica:alkali
(SiO2:Na2O) can vary from 2.5:1 to 4:1, to make a water soluble
"glass", but since the important CaO stabilizer is missing, it
remains soluble in water, and is only effective if it is kept dry.
The only examples that I have seen have been gray and crumbly-- much
like broken up "rock candy".

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

                  Conservation DistList Instance 14:63
                   Distributed: Tuesday, May 22, 2001
                       Message Id: cdl-14-63-003
Received on Wednesday, 16 May, 2001

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