“WIENER BLAU” – natural indigo from Vienna

Before the invention of synthetic dyes, all dyes were based on natural resources. Dyeing with indigo was a possibility to achieve lightfast blue colours on textiles. Woad (Isatis tinctoria L.) was the only source for indigo in Europe for a long time. From the 16th century onwards, it was replaced almost completely by imported tropical indigo, which was replaced, in turn, by synthetic indigo at the end of the 19th/20th century. The aim of the project is to estimate the possibilities to produce natural indigo in organic farming and in the region, i.e. Vienna and the surrounding areas (“Wiener Blau”). The species suitable for our climate are woad and dyer’s knotweed (Polygonum tinctorium Ait.). As a first step, we want to find out which quality can be achieved compared to samples available at the market and what needs to be further optimised. The indigotin content in the extract will serve as quality criteria. Indigo has to be extracted from fresh plant material, therefore plants are cultivated for the project. Different extraction methods described in literature will be tested. The indigotin content in the extracts produced in the project compared to the samples available at the market will be determined by photometric methods.