Cleaning a dolphin skull and mandible to enable assessment of an unusual mid-nineteenth century scrimsham

A very dirty skull and mandible of a rough-toothed dolphin with two scrimshaw images engraved on its surfaces needed to be cleaned so that the artwork could be properly assessed. A suitable and effective method of cleaning the bones was required which would not damage the artwork and, in particular, would not adversely affect the pigment used in the scrimshaw. No method could be found in the published literature so an existing gentle technique for cleaning osteological museum specimens was tried. After tests on the specimen provided good results, a conservation grade non-ionic detergent was used: Synperonic A7 alcohol ethoxylate. Small areas of the bone surface were gently swabbed with very small amounts of a dilute solution of the detergent in distilled water, then swabbed again just with distilled water and dried immediately with paper towels. The cleaned scrimshaw proved interesting. It shows a sailor by a ship's wheel and a three-masted ship under sail, rigged with a 'main spencer' and was probably engraved between 1830 and 1860. Pictorial scrimshaw left on a complete bone such as a skull or a mandible is unusual.