Risks of DYLUX recording of watermarks

I am presently involved in a bibliographical project that is recording
watermarks using the method developed by Thomas Gravell (_A Catalogue of
American Watermarks_, New York: Garland Publishing, 1979). This
technique is like beta-radiography in that it makes a contact print of
the watermark except that exposures are made utilizing florescent 'Cool
White' light instead of a radioactive source.

I am dragging a desk lamp into my institution's library that contains 2
15-watt Cool White tubes and exposing leaves of paper for up to 20
minutes at distances between 1 and 3 inches.  How much of a bad thing is
this?  The UV spectrum is what activates the DYLUX paper which records
the watermark, so it must be somewhat damaging.  I was told rather
off-handedly that this kind of exposure is tantamount to leaving a book
on display in a florescent-lit room for a few days.

Also, when making these exposures it is imperative that the leaf with
the mark be perfectly flat.  What I would like to do is open the rare
book, place two pieces of beveled-edge glass with the DYLUX in between
under the leaf with the watermark, then lay the leaf on top. In order to
insure that the paper remains flat, I would like to place another piece
of beveled-edge glass on top with a few cotton-covered lead weights,
like so:
                           _____________
                          /             \
                         /_____LIGHT_____\
                             /   |   \

               |%%%%|    <--Lead weights-->     |%%%%|
Glass >>       ---------------------------------------
               _________ Leaf in rare book ____________
Glass >>       --------------------------------------- \
DYLUX Sheet>>  ***************************************  \
Glass >>       ---------------------------------------   \___________


Can anybody suggest alternative materials to use for this procedure, or
is this approach a relatively decent way to win friends and influence
people in the curatorial world?  Or at least keep them from bludgeoning
me as a destructive bibliographer?

I would appreciate any and all comments.  Thanks very much!

Brett Charbeneau
Williamsburg Imprints Program
Colonial Williamsburg Foundation
P.O. Box 1776-MHW
Williamsburg, VA 23187
804-229-1000
Fax: 804-221-8948

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                  Conservation DistList Instance 7:59
                Distributed: Tuesday, February 15, 1994
                        Message Id: cdl-7-59-010
                                  ***