Hoof glue

I have recently analyzed by peptide mass fingerprinting samples of
both a paint binder/ground and a glue that appear to be
keratin-based.  Successive samples into the layers were all the same
precluding the possibility of a spurious surface layer.  The samples
are from an archaeological wooden Roman shield dating to around 300
AD.  In each case there is no indication of the presence of collagen
or other protein.  I have not found anything in the literature about
keratin-based glues except for a citation in Wikipedia

    Michel Feugere
   "Weapons of the Romans"
    Tempus, 2002

which, coincidentally, mentions their use in Roman shields.  This is
the first time I have encountered non-collagen-based glues in any
object or painting, and I would appreciate information or
occurrences that others may be aware of as well as a source of an
authentic reference sample.  Thanks in advance for your help,

Dan Kirby
Conservation Scientist
Milton, MA


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                  Conservation DistList Instance 29:10
                  Distributed: Thursday, July 30, 2015
                       Message Id: cdl-29-10-010
                                  ***