Cristoid Film

Can anyone help with a research source on Cristoid film?  It was
manufactured by Sandell & Sons, in London, c1899-1914 (?) and was used
quite a bit by Frederick Evans, et al.  I'm interested in its chemical
composition, manufacturing and processing because of pending
duplication/conservation work on some negatives.  Its double gelatin
structure is what I am most interested in.   I checked Luis Nadeau's
process encyclopedia first and have been unable to find many other
references.

Roderick Hook
Archivist & Conservator
Imageworkers

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                  Conservation DistList Instance 8:60
                Distributed: Thursday, February 2, 1995
                        Message Id: cdl-8-60-012
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