Scientific characterisation of the dyes, pigments, fibres and wood used in the production of barkcloth from Pacific islands

Abstract

Barkcloth production is one of the most distinctive traditions in Oceania. The aim of this work was to investigate the materials used to create 36 objects from the British Museum’s Oceania collection associated with this tradition, including a selection of clothing items (such as loincloths, tiputas and ceremonial head-dresses), beaters and beating boards from various Pacific Islands. A range of scientific analyses were carried out to identify the fibres and colouring materials (dyes and pigments) used in the barkcloths and the wood used for beaters and boards. Scanning electron microscopy (SEM) revealed that plants used for barkcloth include Broussonetia papyrifera (paper mulberry), Artocarpus altilis (breadfruit tree), Ficus spp. (fig/banyan) including Ficus prolixa, Pipturus albidus (māmaki) and Hibiscus tiliaceus (hau, beach hibiscus). Syzygium effusum, Eugenia reinwardtiana, Acacia koaia and Styphelia tameiameiae were identified as the woods used to produce the barkcloth beaters and beating boards. FTIR and Raman spectroscopies indicated the use of reddish-brown earths, dark clays and carbon-based blacks from vegetable precursors among the pigments; high pressure liquid chromatography coupled with electrospray ionisation and quadrupole-time of flight detection (HPLC-ESI-Q-ToF) highlighted the use of noni (Morinda citrifolia), turmeric (Curcuma longa), indigo and tannins as the main dyes. The results of FTIR and HPLC-ESI-Q-ToF analyses provided preliminary information on the painting materials, suggesting the predominant use of binding media from vegetable sources (most likely gums and plant exudates, possibly containing oils and resins). Proteins were also identified on a number of objects, but further investigations are needed to clarify the use of binding media. An attempt was made to identify patterns for the use of certain materials in specific areas, but, despite some interesting results, the database needs to be expanded.