White residue on leather

Laura Cunningham <lcunningham [at] torontopubliclibrary__ca> writes

>The Toronto Reference Library has four, full-bound leather books
>from 1808 which are covered in white, circular streaks that appear
>to be from a previous application of a leather dressing or
>consolidant.  It is unknown when this dressing was applied, but it
>is believed that it was prior to the 1980s.
>
>The substance is hard and brittle. Under low magnification, it is
>opaque, shiny and opalescent.  It appears to be somewhat
>crystalline.

What you may have is the remains of a soluble nylon treatment. There
is much written on this back in the 1980's (eg. Sease Studies in
Conservation, Vol. 26, No. 3 (Aug., 1981), pp. 102-110)  as it was a
popular choice in organics conservation 40+ years ago.  I have never
heard of it being used in book conservation, though I did see a
reference of it being used for wet paper, so it is not
inconceivable.

The only successful removal treatment I know of is using ethanol at
warm temperatures, and unfortunately this does not always work
either.  I hope I am wrong, as its removal has always been
problematic and applying heat to old leather is certainly not
advisable.  If it is soluble nylon, however, it would be a good
thing to remove as much as you can, as it would only do the leather
more harm to remain as it tends to shrink and become more stiff and
insoluble with time.

Linda S. Roundhill
Art and Antiquities Conservation, LLC
Woodinville, WA


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                  Conservation DistList Instance 23:36
                  Distributed: Monday, March 22, 2010
                       Message Id: cdl-23-36-002
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