Analysis of natural dyes and metal threads used in 16th -18th century Persian/Safavid and Indian/Mughal velvets by HPLC-PDA and SEM-EDS to investigate the system to differentiate velvets of these two cultures

Abstract

Introduction: Analyses of natural dyes and the metal of the metal-wrapping threads used in 16 th -18 th century Persian/Safavid and Indian/Mughal period velvets were performed on these textiles in the collection of The Metropolitan Museum of Art. The purpose was to determine whether velvets from the two cultures, which have shown problems in the past with attribution based on historical and iconographical studies, could be more precisely differentiated with the additional evidence from identification of their natural dyes and metals along with information of weaving techniques. Dyes and metal of the metal-wrapped threads from fifteen Persian velvets and six Indian velvets were analyzed by high performance liquid chromatography with photo diode array detector and by scanning electron microscopy with energy dispersive X-ray spectrometry respectively. Results: There seem to be types of dyes which specifically characterize the velvets of each culture, as well as types of dyes commonly found in velvets of both cultures. Dyes typical of Persian velvets are cochineal and yellow larkspur, while lac and turmeric are characteristic of Indian velvets. The dyes commonly found are a combination of yellow larkspur and indigo dye in green, as well as safflower, indigo dye, soluble redwoods, and tannin dye. There were exceptions however. Because of those exceptions, examining the range of dyes used in the velvets would be important in differentiating the velvets. Metal used for wrapping the threads was in all cases found to be silver of fairly high purity, the majority of which had been gilded. The silver from Persia metal threads showed very slightly higher copper content, while Indian threads showed nearly pure silver. This is the first extensive comparative study of dyes and metal threads of Safavid and Mughal velvets: the first evidence of yellow larkspur being the most used yellow dye in Persia, and of the possible differences in the two cultures' metal threads.

Traditional Yellow Dyes Used in the 21st Century in Central Iran: The Knowledge of Master Dyers Revealed by HPLC-DAD and UHPLC-HRMS/MS

“…Based on the HRMS/MS spectra, the more intense signals at 18.63 (6.08) and 19.03 (6.41) min were identified as rutin and quercetin-3-O-glucoside, respectively, in accordance with previous results [21,22]. Minor peaks eluting at 19.77 (6.66), 19.87 (7.03), and 20.33 (7.43) min were assigned to O-glycoside derivatives of kaempferol. Although the more abundant yellow components were 3-O-glucoside flavonols, signals related to their aglycones were not found in the dyed wool extracts.…”

“…On the other hand, chromatographic profiles of extracts from textiles dyed with these plants could only be found in cultural heritage studies for D. semibarbatum, Table 1. For this biological source, we had access to both the characterization of the plant extracts and of the solutions extracted from textiles [19]. For the other natural sources studied in this work, data on the yellow chromophores were only available for the plant extracts.…”

“…HPLC-DAD-MS remains one of the best methods available for identifying the colorants used in historical works, and can provide information as to where, when, and how historical and archaeological textiles were made, allowing their quantification when a calibration curve is used [24]. The main published works using HPLC-DAD or HPLC-DAD-MS for characterizing yellows in Persian textiles were carried out at Boston University, at the University NOVA of Lisbon (Department of Conservation and Restoration), and at the Metropolitan Museum of Art, MET, (New York) [19,[25][26][27]. The main results are listed in Table 2 and show that in the Portuguese collections, the main chromophores are based on luteolin-7-O-glucosides, and in the MET collection, on flavonol 3-O-glycosides.…”

“…The main results are listed in Table 2 and show that in the Portuguese collections, the main chromophores are based on luteolin-7-O-glucosides, and in the MET collection, on flavonol 3-O-glycosides. In two of the publications, the authors proposed as plant sources Reseda luteola in [26], Delphinium semibarbatum, and Carthamus tinctoria in [19]. For more details, please see below.…”

“…Persian velvets embellished with metal threads in the MET collection were studied by Shibayama et al by HPLC-DAD [19]. These authors proposed the use of yellow larkspur (Delphinium semibarbatum) based on the identification of quercetin 3-O-hexoside, kaempferol 3-O-hexoside, and isorhamnetin 3-O-hexoside as the main flavonoids ( Figure 1 and Table 2).…”