Beta-radiography plates

Siew Wah Lee <lee_siew_wah [at] nhb__gov__sg> writes

>Beta plate is used for recording watermarks on paper. It contains
>C14 inside a sheet of polymethyl methacrylate, and gives out Beta
>radiation. I would like to know whether people are still using it
>for imaging watermarks, as the plate do gives out radiation, i.e.
>radioactive. Also what are the health and safety considerations in
>terms of storage, handling, exposure, etc. in the conservation lab.

I am a graduate student in the Art Conservation Program at Queen's
University, Kingston, Canada. I am specializing in paper
conservation, and I have been doing some work on watermarks this
year in my lab class. With the assistance of my professor John
O'Neill, I have been using a beta plate owned by our program to make
images of watermarks and we have made about a dozen images on x-ray
film in the last two months. Once the correct exposure time was
established, I found the process very effective and satisfying.

According to my professor, the level of C14 in the plate is so low
that occasional handling does not affect the user at all. We are
required to keep the plate in a locked location when not in use, and
my professor is the only one licensed to actually handle the plate,
but students use it with his assistance quite frequently.

As a side note, I have been working with another professor, George
Bevan, on a project using Reflectance Transformation Imaging (RTI)
in an attempt to record usable images of watermarks. We have been
comparing this technology to beta-radiography, and have found that
although beta-radiography is definitely more effective for producing
clear images, in some cases RTI can also produce useful images, at a
fraction of the cost and time. If you have any questions about the
technique you can reach him at bevan<-a t->queensu< . >ca. We hope to publish
our findings shortly.

Jennifer Robertson
Paper Conservation Graduate Student
Queen's University
Kingston, Ontario, Canada


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                  Conservation DistList Instance 24:48
                  Distributed: Tuesday, April 19, 2011
                       Message Id: cdl-24-48-004
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