Identifying parchment

James Elwing <elgur [at] acay__com__au> writes

>I have a problem I have not experienced before, distinguishing
>animal from vegetable parchment. The document is an Italian
>university degree from 1933 which has slight mould. It has unrolled
>with humidification and difficulty It is mottled dark and hard. I
>have assumed it to be vegetable parchment, probably supported by its
>pH of  approximately 3.75, and the fact that I have never seen
>parchment or vellum go so dark or hard, but it cockles to some
>extent similar to true parchment.

Parchment can be easily identified by light microscopy by using just
a minute sample, if sampling is possible.  Viewing it only in water,
it  shows typical collagen bundles, and if polarized light is used,
shows brilliant birefringent colors. An alkaline solution can be
draw under the slide cover, the collagen will swell dramatically.
Plant fibers show a distinctive cell wall along the length of the
fiber. The dark color--if parchment, sounds like over treatment with
thymol which is adsorbed without constraint by parchment--it has an
insatiable desire to drink it in--to the point of almost
solubilizing the collagen,. This darkens it. Check the  conservation
treatment records to see if this may be the cause of the darkening.

Mary-Lou Florian
Research Associate Royal BC Museum


                                  ***
                  Conservation DistList Instance 15:76
                   Distributed: Friday, May 10, 2002
                       Message Id: cdl-15-76-003
                                  ***