Traditional dyeing methods for preparing dyed silk model tapestries were taken from a mid-sixteenth century Italian treatise (the Plictho). Instructions for mordanting silk with alum and iron, and dyeing with madder, brazilwood, weld, dyer's greenweed and young fustic were interpreted and converted to metric units. An early seventeenth century European treatise (De Nie) was used for the dyeing of silk red with cochineal. Expertise was sought from SPINDIGO, another EC-funded project, for dyeing with wood/indigo.
To ensure that the correct biological source was used for the models, authentification was undertaken by analysing test samples and dyeings with high performance liquid chromatography with photodiode array detection (PDA HPLC). The yellow and redwood dye sources used were confirmed as Reseda luteola L. (weld), Genista tinctoria L. (dyers' greenweed), Pterocarpus santalinus (sanderswood), Caesalpinia sappan L. (brazilwood) and Curcuma longa L. (turmeric). Commercial sources of Cotinus coggygria L. (young fustic) were not botanically correct, but supplied instead by the Association de Garance in Lauris, Provence, France.
These well-characterised references were essential for identifying the dye sources of the historic samples as well as for modelling ageing behaviour of tapestry materials. Their value as standards extends beyond MODHT, for example in the exchange of expertise to develop a dye analysis strategy for heritage textiles though EU-Artech, a COST G8 network.