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Subject: Blood


From: Ellen McCrady <whenry>
Date: Thursday, November 29, 1990
Karen Pavelka asked about identifying blood and whether there was a way
to keep it from fading in light or dark storage.  I don't have any
answers, only comments.  Walter McCrone distinguished blood from two
artist's pigments in his paper on the Shroud of Turin at AIC in 1986.
Forensic scientists identify blood all the time, I understand from
mystery plays on TV.  There are standard reference books in the library,
used by forensic scientists, telling how to identify substances
(including blood) by spot tests.  As for light fading, I would guess
there is no good way to prevent it except by protecting the stuff from
light.  The Germans have done some good work on fixing inks, which
decreases water solubility, and the paper chemists now talk
optimistically about ways to keeping newsprint from yellowing, but I
think conservators would be the first to know if there was a way to
render something less vulnerable to light.  As for dark fading, as a
general rule I think you should get good results by excluding oxygen,
pollutant gases, moisture and heat, or at least minimizing them, because
this will slow down chemical changes. Remember the bright colors that
were observed in the tombs of the pharaohs when they were first opened,
and how the colors faded after tourists had breathed on them for a few
decades?  (I know you can't remember 70 years back, but you know what I

                  Conservation DistList Instance 4:30
                 Distributed: Sunday, December 2, 1990
                        Message Id: cdl-4-30-001
Received on Thursday, 29 November, 1990

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