Paid Post-graduate Interns at CCI — 2009
Jessica Lafrance
I began my internship in the Archaeology Lab at CCI in October 2008, prior to which I had obtained a diploma in Applied Museum Studies from Algonquin College of Applied Arts and Technology (2005) and a BSc in Conservation of Objects in Museum and Archaeology from Cardiff University (2007). I had also completed internships in archaeological conservation with the Museum of London, the Newport Ship Project, and Parks Canada, and served as a conservation lab assistant at Algonquin College.
While at CCI, I have been working on rubber and leather shoes and fragments (1850–1870) from Old Songhees Reserve / Shutters Site in Victoria, BC. The rubber objects are particularly interesting and challenging, presenting a great variety in the thickness, texture, type, and colour of rubber as well as the level of degradation.
These rubber shoes and fragments had been buried in clay within a metal cistern. As the cistern corroded over time, it left corrosion products and stains on their surfaces. In some cases, corrosion processes had caused whole pieces of the cistern to bond to the rubber surface.
Mechanical removal of the corrosion products has been possible only on the thick outer layers of rubber. The thin inner layers cannot withstand even the lightest mechanical cleaning, so a chemical removal method has been devised, tested, and used on a case-by-case basis for them. Following removal of the corrosion products, calcium and chlorides must be removed (these salts had been absorbed from the burial environment and, if the rubber is dried before they are removed, they may migrate to the surface and harden/crystallize). Once all the residues are removed, the rubber can be reshaped and dried. When treatment is complete, the rubber objects will be packed in an oxygen-free environment to prevent further deterioration.
The various materials used in the manufacture and vulcanization of rubber make it very unstable and susceptible to oxidation. However, because vulcanized rubber is a relatively new product, it has not been treated often and literature is limited. Therefore, treatment options to slow degradation of rubber are still severely restricted.
