FTIR characterization of archaeological dyed cords and fibers from Southern Argentinean Puna (ca. 8500-400 years BP)

BABOT M. DEL P.; BEN ALTABEF A.; APELLA M. C.

Buenos Aires

Congreso; Ninth Biennial Conference of the Infrared and Raman Users Group (IRUG 9); 2010

Facultad de Cs. Naturales y Exactas de la UBA

Trends and changes in the use of dyeing materials on archaeological manufactured camelid and plant fibers, are just starting to be studied in the Sourthern Argentinean Puna. Our research considers a broad sample of dyed cords and camelid fibers from several archaeological sites located in Antofagasta de la Sierra (Catamarca Province), that covers a broad time spam, from 8500 to 400 years BP (Babot et al. 2006). Particularly, this paper deals with the identification of the natural sources of color, mordants and other additives for the dyeing process by means of the physicochemical characterization of archaeological samples through Fourier-Transform infrared spectroscopy (FTIR). Small fragments of 2-3 mm of samples were placed into KBr discs and run from 4000 to 400 cm-1 with a 2 cm-1 resolution in transmittance mode with an FTIR Perkin Elmer GX1. Fragments were recovered for further analysis. Infrared spectra of archaeological samples were assigned by comparison to those of modern dyeing fibers and published data. We tested archaeological hypothesis related to color and mordant sources on the base of a previous list of potential dyeing materials significant to our regional problem (Babot & Apella 2009). As a result, we could establish four main groups of dyed cords and fibers that group samples on the base of the combination of a generic chemical compound plus a specific mordant or additive as follows: 1)     Quinones related to alizarin and purpurin plus aluminum potassium sulphate (alum) or calcium carbonate as a mordant. 2)     a. Tannins, lichenic acids and/or carotenoids without a mordant or b. Flavonoids and/or carotenoids plus calcium oxalate mordant. 3)     Indigoids plus alum and/or calcium carbonate additives. 4)     Tannins plus ferrous sulphate (iron) as a mordant.