Architectural drawings

Kathryn Kidd <paperkate [at] yahoo__co__uk> writes

>We are currently working on architectural drawings on tracing paper
>from the 1930's to the 1970's, and are encountering problems unique
>to this type of collection. The primary problem is paper edge tape
>which was applied by the architectural firm to protect the edges of
>the support, but is now losing its adhesion and is coming away,
>leaving exposed adhesive. ...

Your problem of the edgetapes interests me very much. In 1982, I
published an article with David Enke on "Stages in Deterioration:
The Examples of Rubber Cement and Transparent Mending Tape" (in
Science and Technology in the Service of Conservation, Brommelle and
Thomson eds. IIC 1982,19-23)  We demonstrated that as many such
materials age they may develop peroxides and pass through a "sticky"
stage (in which adhesion will suffer), after which the adhesive
material is likely to become gradually less readily soluble. Because
of the latter aspect, we suggested that the sticky stage marks the
time that one should begin to think about removing the material.

There are several aspects of your encounter with this problem that
have interest to those of us who study the reasons and manner in
which organic materials deteriorate:

    1.  We are interested in the "induction time" before a problem
        of deterioration "shows up". Therefore, if there is some
        indication of the times, even in a general sense, when the
        tapes were applied, you might note their behavior passing
        through various states or stages. To confirm that behavior
        in "real time" experience would be valuable information.
        (Our Fig. 7 followed discoloration of rubber cement over a
        period of 20 years).

    2.  Many of us are interested in the role that peroxide
        formation may play in long term deterioration. There has
        been little or no information that peroxides have been
        detected in any museum conservation situations. (Peroxide
        seems to be at its maximum level in the sticky stage. I
        found it significantly present in an industrial tape that
        had become soft and sticky on a carton after some years).
        This is "rather academic" as far as your immediate problem,
        I know,but if a suitable sample is available and if the help
        of a chemist can be called upon, the demonstration that
        considerable peroxide had been built up, would do much to
        advance our understanding of the phenomenon.

    3.  It would of course be useful to know the brand(s) of edgetape
        used. An infrared analysis of the adhesive material could be
        useful in identifying its basic chemical composition.

I have no direct experience with the conservation treatment in such
a problem as you describe, conservators at the Library of Congress
have written extensively on the subject of mending tapes. However,
if as a chemist (very much retired) I can be of further help, please
do not hesitate to contact me. Very truly yours,

R.L.Feller


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                  Conservation DistList Instance 19:13
                 Distributed: Friday, September 2, 2005
                       Message Id: cdl-19-13-013
                                  ***