Cellulose nitrate

Has anyone ever found white, acicular crystals growing on the
surface of a cellulose nitrate object?  We recently removed a chair
upholstered in faux-leather from exhibit after 12 years and found
the sides and part of the back fairly uniformly covered with the
crystals. The crystals brush off easily and there is no visible
damage to the surface.  I tested the coating of the upholstery and
found it to be cellulose nitrate, which is common in faux-leathers.
The chair was made in the 1950's.  There was no camphor smell, or
other odors, and none of the other objects in the case with the
chair underwent any changes, so we have ruled out VOC's from the
case materials. The crystals were soluble in water, ethanol and
acetone.

I do not have access to FTIR, but hope to have that done eventually.
There was a recent post by Ellie McFadyen Supervising, Conservator
(Preventive), of the National Archives of Australia, that mentioned
that she identified white needle-like crystals of triphenyl
phosphate on a cellulose acetate object.  My thoughts are that the
crystals are also the sublimate of a plasticizer from the cellulose
nitrate that slowly grew in the still air of the case.  I would be
interested if anyone else has ideas on this.


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                  Conservation DistList Instance 18:21
                 Distributed: Tuesday, November 9, 2004
                       Message Id: cdl-18-21-004
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