M. Járó - L. Költő szerk.: Archaeometrical research in Hungary (Budapest, 1988)

Analysis - TIMÁR-BALÁZSY Ágnes: Investigation of dyes on textiles from the collections of Hungarian museums

32. Spectroscopic methods Abrahams and Edelstein applied infrared spectroscopy for identifying indigo, saffron and madder on textile finds from 135 A. D. [35]. Masschelein-Kleiner and Maes also used this analytical method when investigating Nubian, Palestinian and Egyptian textiles dated between the beginning of our era and 600 A. D. Indian madder, purple, weld, madder, carmine acid and gaflotannins were identified [36]. The infrared spectra of indigo and purple were published by Schweppe [37]. In her basic work on natural dyes Hofenk de Graaff gives the infrared spectra of the introduced dyes [22]. On the basis of their UV/visible spectra Whiting identified dyes on ancient oriental textiles [38] and Saltzman on Pemvian pieces [39.]. Taylor presents a detailed account of dye determination by UV/visible spectrometry when reporting about his results in dye analysis of textile finds from a Viking settlement in York [40]. The same method was used by him for the identification of dyes on Romano-British textile finds [17]. He provides the UV/visible spectra ef 6 kinds of lichen in a publication discussing the tracing of lichen dyes [41]. Dalrymple also applied UV/visible spectroscopy for determining dyes on a 17th century dance costume [42] and on Scottish tartans [43]. Harvey identified dyes of textiles from the Mary Rose ship from the 16th century [44], Daniels investigated plant and animal dyes [45], and Taylor determined purple with the help of UV/visible spectroscopy [46]. A fluorescent assay of quinone, anthraquinone, lichen dyes and redwood was published by Wallert [47]. The explanation as to why infrared spectroscopy did not become a wide-spread method is that only the infrared spectra of pure dyes may be considered as a "fingerprint". With mixed dyes one often obtains a spectrum which is unsuitable for analysis. When studying old recipes we often come across mentions of a mixture of dyes or dyeing on a coloured base which method results in a mixture of dyes in the solution. UV/visible spectra of indigo, madder, kermes, cochineal, orchil and redwood were produced for comparing with spectra of 72 unknown samples from excavations or crypts. The working process was similar to Taylor's [40]. I recorded three spectra for the identification of one sample: one for the detection of indigo, another for examining orchil and a third one for proving the presence of madder or insect dyes. Since the samples had no colours (except the so-called "archaeological brown") I used up all the provided samples, which means 50^-500 mg amounts. On 14 samples cochineal, madder, indigo and redwood were identified [18]. 33. Chromatographic methods Masschelein-Kleiner elaborated the identification by thin-layer chromatography of some anthraquinone dyes [48] and she utilized her method to investigate a large number of museum textiles [49 , 50, 51]. In her basic work on natural dyes Hofenk de Graaff publishes the chromatographic identification of the introduced dyes [22]. She identified madder, cochineal, kermes and redwood on textiles dating back to the period between 1450 and 1600 by thin-layer chromatography [52]. Their method for detection flavonoid dyestuffs was published by Hofenk de Graaff and Roelofs [53]. Hofenk de Graaff applied thin -layer chromatography when exarnining dyes on various museum textiles [54, 55]. Schweppe also used this method for investigating historical textiles [31,32,37]. Dalrymple found it a useful method when investigating dyes of Scottish tartans [43] and Hayaski applied it too when analysing Japanese textiles [30]. Walker and Needles report on using thin4ayer chromatography for investigating dyes on Caucasian carpets and American textiles [56].