Cochineal Dyes and Dyeing Techniques in Historical Lielvārde-Type Patterned Sashes from Latvia: Analytical and Historical Evidence

Lielvārde-type patterned sashes are among the most recognisable symbols of Latvian cultural heritage, yet reliable information on their chronology, dyes, and dyeing technologies remains limited. This study investigates the red wool yarns of five historical Lielvārde-type patterned sashes from Latvian museum collections. The study combines UPLC–DAD/MS dye analysis, ICP–QQQ elemental analysis, reflectance-based colourimetric measurements, experimental dyeing, and the analysis of historical sources. The analytical results identified cochineal-derived anthraquinone compounds consistent with Mexican cochineal (Dactylopius coccus Costa) in all analysed samples. Elemental analysis revealed the presence of both aluminium- and tin-based mordanting systems, while experimental dyeing demonstrated that the bright red shades characteristic of the historical textiles were achieved by combining tin mordants with cream of tartar. The identification of tin provides the first analytical evidence for the use of tin-based mordants in historical Latvian peasant textiles. Historical sources further document the availability of cochineal, mordants, and imported textile materials in the Baltic region during the nineteenth century. The combined analytical and historical evidence indicates that the production of the analysed sashes was closely connected to broader European networks of trade, knowledge exchange, and technological development. The results also call for a reassessment of previously proposed dates and support a production period in the second half of the nineteenth century, most likely between the late 1850s and the 1870s. The study contributes new knowledge on historical dyeing technologies and the circulation of imported dyestuffs in the eastern Baltic region.