Restoration of mosaics in situ

In response to Mark Vine's suggestion of using Primal (Rhoplex in
the U.S.) AC-33, I would strongly discourage this application.  If
you check a little further into its properties, AC-33 has a glass
transition temperature of 16 degrees C and will surely exhibit loss
of structural strength during warm periods.  Regarding its freeze
thaw stability, Rohm and Haas states "Rhoplex AC-33 will withstand
five or more freeze-thaw cycles without coagulation... Addition of
other materials, particularly those with high soluble salt content,
may reduce freeze-thaw stability."

Stephen Koob
Department of Conservation and Scientific Research
Freer Gallery of Art
Smithsonian Institution
Washington DC 20560
202-357-4880 x276

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                  Conservation DistList Instance 9:42
                Distributed: Thursday, November 16, 1995
                        Message Id: cdl-9-42-003
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