Recognition of natural silk fibers, dyes and metal threads of historical Romanian textile fragments using the multi-analytical techniques approach

A multi-analytical technique approach involving the combined use of micro-invasive and nondestructive techniques was used to identify the type of fiber, mordant and natural dye constituents for eight historical textiles fragments from the 17th-18th centuries, found in monasteries in Northern Romania. The analysis was performed using optical microscopy (OM), scanning electron microscopy with an energy-dispersive X-ray detector (SEM-EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and high-performance liquid chromatography (HPLC). HPLC could determine two flavonol-based structure yellow dyes (possibly weld and Persian berries), one naphthoquinone-based structure brown dye (juglone-walnut) and five samples composed of anthraquinone-based structure red dyes (two fragments contain kermes, one cochineal, one lac and one madder). Elemental analysis using EDX was utilized to identify the possible using of alum as a mordant and the use of metallic threads (pure silver and gilt threads). OM and SEM techniques identified the fiber type and the existence of metal threads, while ATR-FTIR analysis could provide an initial idea about the functional groups of the textile components for the fiber structure substrates.