The scientific study of the materials used to create the Tahitian mourner's costume in the British Museum collection

Abstract

• The British Museum houses one of the few examples of a complete mourner's costume from Tahiti in the world. For the 250th anniversary of Captain Cook's first voyage, the costume was displayed for the first time in over forty years. The conservation assessment of the numerous parts that compose the costume provided a unique opportunity to undertake scientific analyses with a particular focus on the plant materials (wood and fibres), the dyes and the pigments. Non-invasive investigations, including observations using ultraviolet light and fibre optic reflectance spectroscopy (FORS) suggested the presence of turmeric (Curcuma longa) and red ochre in some of the yellow and red areas respectively. Several samples were then taken. Scanning electron microscopy (SEM) was used to identify the plant materials, such as paper mulberry (Broussonetia papyrifera) for all the barkcloth components, coconut (Cocos nucifera) fibres for the cordage, Pandanus sp. leaves for a plaited cap and Pacific rosewood (Thespesia populnea) for a figure discovered inside the costume in the 1960s. High performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was also used to confirm the presence of turmeric, identify noni (Morinda citrifolia) dye in some red areas, and an unknown red dye, probably extracted from a plant belonging to the Musaceae or Haemorodaceae family, was also found. Raman spectroscopy enabled carbon black to be identified in the black areas. The materials were consistent with local sources. This work reports the first scientific confirmation of the use of these materials in such a unique and precious object and, considering the limited examples of such costumes, the results will be extremely useful to other researchers.