J.IIC-CG VOLUME 14 (1989)
An Improved Method for Solvent Extraction of Oil from a Whale Bone Sculpture
Removal of oil from a sculpture carved out of fresh, or “green,” whale bone is described. In view of the possibility of a drying oil having being applied after carving, analysis of the oil was performed. It proved to be whale oil, which is less unsaturated than typical drying oils, and thus it is not very susceptible to drying by oxidation. From several possible treatments, the choice was made to extract the oil by soaking the whole sculpture in 1,1,1-trichloroethane within a specially constructed container. In order to minimize solvent volume and loss by evaporation, a tight fitting polyethylene bag surrounded by a water jacket was used to enclose the sculpture; the solvent was then circulated by pumping it out of one end of the bag, purifying it by distillation, and returning it to the other end. An approximation of solvent purity was obtained by monitoring the optical density of the outflow daily with a rudimentary light beam/photocell densitometer. On completion of the treatment, the sculpture was mounted on a specially constructed display stand.
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