Aniko Bezur, Director of the Technical Studies Lab (IPCH),  visited the Gates Conservation Laboratory last month with a portable XRF device.  She and YUL Paper & Photograph Conservator, Marie-France Lemay, tested a sample of silked manuscripts recently found in a collection being processed.

Silking was a restoration method used with some frequency in the 19th and early 20th centuries to preserve important papers.  There were a number of different variations of the basic technique, that laminated documents between sheets of thin white silk or crepeline.  The adhesion of silk was achieved with a starch paste of rye or wheat flour, to which alum, oil of cloves, wintergreen, thymol, and/or arsenic was added.  Arsenic was used extensively in taxidermy as an insecticide or fungicide. It was most likely added to silking pastes to serve the same purpose.  Conservators considering treatments for silked documents must also assess the potential risks posed by any arsenic that might still be present in the paste.  Bezur and Lemay’s initial investigation with XRF detected traces of arsenic.  They will be continuing their analysis of the rest of the collection of silked documents later this fall.