Cellulose nitrate-coated Solander boxes

We'd like to know if anyone has encountered Solander boxes that
appear to be flaking their black finish.  During a recent survey,
WACC paper conservators discovered tiny flakes of a black substance
which had adhered to the outside surface of mats containing works on
paper.  The matted works were stored inside Solander boxes.  We
analyzed the flakes and a sample of the black finish from one box
using infrared microspectroscopy (IMS, or FT-IR microscopy).  IMS
analysis showed both sets of materials to be the same--bone black
pigment dispersed in cellulose nitrate (a.k.a. nitrocellulose,
pyroxylin).

Caldararo has reviewed the history of the Solander box, and
describes the black finish used by several manufacturers as
pyroxylin based (Museum Management and Curatorship (1993) 12,
p.392).  Some finishes were reported as acrylic, while others were
unknown.  Caldararo includes Anne Clapp's earlier caution regarding
the stability of this pyroxylin-based finish, saying that it
degrades with liberation of nitric acid (Curatorial Care of Works of
Art on Paper.  NY: Nick Lyons Books (1987): 135).

When the survey resumes we will investigate the extent of the
possible auto-degradation of the black finish on these Solander
boxes.  We would like to know how common this circumstance (I am
deliberately avoiding the word, problem) is in other collections,
and what actions and investigations other facilities have undertaken
by members of the DistList.  This inquiry will be cross-posted to
Materials-L.

James Martin
Director of Analytical Services and Research
Associate Conservator of Paintings
Williamstown Art Conservation Center
413-458-5741
Fax: 413-458-2314

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                  Conservation DistList Instance 10:43
                Distributed: Thursday, October 31, 1996
                       Message Id: cdl-10-43-002
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