Sheet mica mends on pith painting

I am treating a set of three paintings on pith that were mounted in
a 19th century missionary's scrapbook.  The edges of the paintings
were directly adhered to the pages with animal glue.  On the back of
one painting are two very tiny patches of pith, and they are held in
place by what I thought was transparent tape, which was surprising,
(I assumed the painting had been glued in place in the 19th century,
meaning no one in the self-adhesive-transparent-tape generation
would have had access to the back of it).  But on further
inspection, I believe the material to be very thin, transparent
sheets of mica.  Two layers sheared off while I was examining it
under the microscope.  I can't tell what adhesive was used, if any;
it looks like there's no adhesive at all, but it's definitely well
adhered.  Perhaps it was wetted and the pith just stuck to its wet
surface?

Has anyone else encountered sheet mica used as a mending material?
It's quite a clever idea.  Any opaque mend would have showed through
the translucent pith.  I think the pith patches (and possibly the
mica) were adhered before the artist began his work, because the
paintbrush seems to have skipped over the slight bumps.

Additionally, this pith painting has been trimmed to follow the
curving shape of the image, a seashell.  I'm wondering if the artist
would have done that, or the scrapbooker, which is my guess.  One of
the other paintings looks to have been trimmed to fit within a
decorative printed border on the scrapbook page. (The scrapbook also
contains a marmotinto sand painting.  It's a wonderful album of
treasures!)

Grace White
Conservator for Special Collections
Duke University Libraries
Preservation Mailbox #90189
Durham, NC 27708
919-660-5906
Fax: 919-684-2855


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                  Conservation DistList Instance 28:19
                Distributed: Saturday, October 11, 2014
                       Message Id: cdl-28-19-019
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