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Subject: Adhesive for stone

Adhesive for stone

From: Olaf Pung <olaf_pung>
Date: Monday, March 9, 1998
To Helena Jaeschke, thanks for your tips!

The conservation of the sculpture is part of my education at
Fachhochschule Hildesheim, Germany. Therefore I'm doing a little
test-program for stone adhesives in museum-environment. Mechanical
properties of the bond like modulus of elasticity, tensile/shear
strength and creep rupture will be tested with different adhesives
on porous limestone. Paraloid B72 will be enclosed in the testing
program beside wheat starch, methylcellulose, a dispersion of
acrylic polymer (Primal AC33) and others. Properties of adhesives
mixed with fillers (fumed silica, sand, micro-balloons) will also be
tested.

I think B72 will be a good choice for all the smaller parts I have
to fix. Will it also be probable for the bonds that will have to
take more stress, e.g. to fix new dowels? Do you have any experience
with that, especially concerning the "cold creep"?

I didn't mean to consolidate the limestone, because the strength of
the stone is not high, but homogeneous: Consolidation of the bond
areas will only move the weak zone deeper into the stone. Complete
impregnation of the sculpture with a consolidant is out of question,
because it is partly painted.

A conductive test showed that there are no soluble salts. I used a
water-ethanol mixture to loosen old shellac bonded joints, no
efflorescence or discoloration showed.

Olaf Pung

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                  Conservation DistList Instance 11:76
                 Distributed: Wednesday, March 11, 1998
                       Message Id: cdl-11-76-011
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Received on Monday, 9 March, 1998

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