The dyestuff content in historically used dye plants such as madder, dyer’s broom or weld can be subject to greater fluctuations depending upon ground conditions, origin or time of harvesting. In addition the use of various extraction and precipitation methods results in heterogenous chemical compositions of artists’ colorants. On the basis of six selected colorants (Dyer’s Madder - Rubia tinctorum L., Wild madder - Rubia peregrina L., Our Lady’s Bedstraw - Galium verum L., Weld - Reseda luteola L., Dyer’s broom - Genista tinctoria L., Dyer’s sawwort - Serratula tinctoria L.) this range of variation is to be investigated more precisely. Future dyestuff analyses on works of art or archaeological artefacts are to become more meaningful and comparable with the development of protocols for the pretreatment and analysis of extremely small samples, the execution of round-robin tests with partners, as well as the synthesis of rare references. Besides employing High Performance Liquid Chromatography for their analyses the Doerner Institut also wants to test Raman microscopy for this specific purpose.
