Carole Dignard, Amanda Salmon, and Season Tse
Abstract
A 19th century Mi’kmaq birchbark box decorated with porcupine quills and spruce root from the McCord Museum in Montreal was treated at the Canadian Conservation Institute. The box’s black spruce root was brittle and showed extensive losses, and the quilled birchbark lid cover was detached and curved. Dyes and mordants were analyzed: for the black spruce root, iron was confirmed using bathophenanthroline test strips as well as by atomic absorption spectroscopy. Iron and other metal ions are known to catalyze the oxidative degradation of cellulose. The birchbark lid cover required flattening while avoiding any compression of the quillwork decoration. This was accomplished by exposure to methanol vapors, followed by vacuum restraint pressure. The iron-dyed spruce root was chemically stabilized by applying calcium phytate / calcium carbonate solutions by brush. Problems included the swelling of the root during treatment due to absorption of water, and the migration of iron ions causing staining. The spruce root was physically repaired using toned Japanese paper facings or backings and Lascaux 498 HV acrylic dispersion. The quills’ fading rates were measured using the micro-fading technique in order to provide specific display lighting recommendations.