Deterioration of acrylic glazing

Over the past 18 months, the National Gallery of Australia has
noticed a breakdown in some of their acrylic glazing, both old and
relatively new stock. The breakdown has taken form as a white powder
and as a waxy deposit, seen both on the work of art and window mat,
and on the inside of the glazing. This has occurred on
screen-prints, lithographs and silver gelatine prints.

Analysing the deposit using FTIR produced a positive result for
polymethyl methacralate, and SEM/EDXA showed a strong sodium peak.
The glazing itself may have various appearances: slightly pitted,
abraded and a spider web type crazing.

The breakdown appears to be the result of a combination of various
factors: vibration/abrasion, chemical make up of the printing media,
microclimate, and perhaps use and cleaning practices.

Has anyone else noticed such breakdown of acrylic glazing occurring
on framed works, and in what form?

Caitlin Granowski
Paper Conservator - Tyler Project
National Gallery of Australia
GPO Box 1150
Canberra A.C.T. 2601
Australia
+61 2 6240 6546
Fax: +61 2 6270 6414


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                  Conservation DistList Instance 19:16
               Distributed: Thursday, September 22, 2005
                       Message Id: cdl-19-16-019
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