Dyed Not Dead: A Pilot Study of Dye Analysis in Preindustrial Textile Case Studies from Icelandic Collections Using FORS and Spectragryph

In Iceland, dyed textiles carried meanings beyond aesthetics and function. Through textile production and circulation, woollen cloth, including vaðmál as one historically important example, became central to the Icelandic economy and offers a material perspective on technological practice, exchange systems, and regional connections. This paper presents a pilot methodological study exploring the combined use of fibre optic reflectance spectroscopy (FORS) and a reference corpus developed in Spectragryph for the preliminary assessment of possible dye classes in preindustrial textile case studies from Icelandic collections. The approach provides a rapid, portable, and non-invasive framework for spectral comparison prior to complementary molecular analysis, with targeted LC–MS of selected archaeological textiles planned as the next phase of the research. Following botanical and ethnographic research, a reference corpus of 351 wool samples was assembled, including undyed fleece controls, experimentally dyed fibres, and ethnographic dyed yarns preserved in museum collections. Seven case studies are presented, comprising four archaeological textiles and three early modern ecclesiastical textiles preserved in the collections of the National Museum of Iceland. The spectra show reflectance features consistent with possible indigoid and anthraquinone-related dye classes in several of the analysed textiles, whereas possible flavonoid- and tannin-related patterns generally remain non-diagnostic. At the same time, degradation, contamination, natural fleece pigmentation, and overlapping chromophoric signals frequently complicate interpretation, particularly in archaeological materials and darker tonal ranges. The study illustrates the potential of FORS combined with structured spectral comparison as a non-invasive first-stage methodology for dye analysis in Icelandic textile case studies, while highlighting the limitations of reflectance-based interpretation and the need for complementary molecular analysis for definitive compound-level identification.