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Subject: Reversibility of Paraloid B-72

Reversibility of Paraloid B-72

From: Stephen Koob <koobsp>
Date: Tuesday, May 29, 2007
Tietjen <lena-t [at] gmx__de> writes

>I am working on a bronze object that has been consolidated with
>Paraloid B-72 three years ago. This is my Diploma- project for
>Object conservation at the Fachhochschule fuer Technik und
>Wirtschaft in Berlin. I am asking myself now, if someone has
>experienced that Paraloid B- 72 is not soluble after a certain
>period of time. Although Paraloid does hardly change with time, it
>might get irreversible after 10-20 years. Has someone tried to
>dissolve Paraloid after more than 10 years?

I have been working with B-72 for over 20 years, and I have never
seen any problems with reversibility.  In fact, it usually dissolves
away with just a "rinse" of acetone.  I have numerous adhesive and
film samples that I made up in 1984 and they are still easily and
completely soluble in acetone.

In discussions that I had with Robert Feller many years ago, the
ageing characteristics of the resin will eventually include some
minor molecular chain scission along with some crosslinking.  Dr.
Feller estimated that these may occur at the same rate, thus keeping
B-72 at its current solubility for well over 100 years, and possibly
much longer.

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

                  Conservation DistList Instance 21:9
                   Distributed: Friday, June 8, 2007
                        Message Id: cdl-21-9-003
Received on Tuesday, 29 May, 2007

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