AIC's 44th Annual Meeting

A survey of approximately 150 artifacts with resinous materials or residues at the Arizona State Museum were characterized using multiple techniques including UV examination, micro-chemical tests, and Fourier transform infrared spectroscopy (FTIR). A special focus was placed on micro-chemical testing, which is an invaluable tool in conservation as often analytical instrumentation is not available. Especially useful was a reevaluation of the o-toluidine test, which can distinguish between gum/mucilage and starch. A new test was developed to confirm the presence of unprocessed lac based on the color change of dyes in the resin in the presence of alkali. The study identified problems encountered with each technique that may lead to misidentification. As part of a Save America’s Treasure Grant, basketry, sandals, wood artifacts, bows, arrows, textiles, cordage, vegetal artifacts, and botanical specimens representing 2000 years in the US Southwest were identified. Those with resinous material were selected for further examination and analysis. The peoples of the southwest used a variety of organic materials including pine resin, plant carbohydrates such as mesquite gum and mucilage prepared from cacti flesh and roots, and creosote lac (a resin exuded from the insect Laccifer larrea that is similar in composition to shellac). This study found that resinous materials are often misidentified and the terminology is inconsistent in the archaeological, ethnological and ethnobotanical literature. Consequently, museum records are often erroneous. Results from the collaborative work of conservators and conservation scientists identified regional differences in the use of various gums and resins. These differences reflect different environmental regions. Also, there is evidence that cultural groups within the regions utilized and processed resinous materials in different ways possibly reflecting cultural traditions or trade.