Numbering plastic objects

Bonnie Baskin <bonnieasia [at] yahoo__com> writes

>Brenda Keneghan <b.keneghan [at] vam__ac__uk> writes
>
>>We are trying to establish the current practice in numbering plastic
>>objects. We would like to hear from DistList readers to hear what
>>media they use.
>
>...  When labels must be affixed to plastic, do a
>solvent check before using organic solvents or water.  In my
>experience, which includes numbering some older and fairly degraded
>plastics, deionized water was not disruptive ...

I just want to remind folks about  the importance of not using water
on cellulose nitrate plastics if it can be avoided.  While CN  is
fully waterproof when new, age makes it increasingly hygroscopic and
susceptible to damage by water.  Even if it does not appear to
respond during a test, there may be a chemical reaction started that
will continue to progress. Also, if a water-soluble glue ever has to
be removed in the future, the object may have become even more
sensitive over time and reversing the glue may destroy the object. I
have witnessed normal-looking but degraded CN swell like gelatin and
crumble in the presence of high humidity, let alone liquid water.

Linda S. Roundhill
Art and Antiquities Conservation, LLC
Woodinville, WA
USA


                                  ***
                  Conservation DistList Instance 21:54
                  Distributed: Friday, April 11, 2008
                       Message Id: cdl-21-54-004
                                  ***