Historical Data
Dye analyses of Turkish rugs and flatweaves from the 19th century show that Rumex sp roots were often used together with Rumex olympicus and indigosulfonic acid to dye green. Personal experiments showed that such a green can be very quickly produced: the yarn is heated in a dye bath of Rumex sp. roots, indigosulfonic acid, and alum, and within only half an hour the green appears. When the blue from the water-soluble indigosulfonic acid later washes out, the yellow from Rumex is left, which turns brown, and then is often taken for camel's hair. Rumex species, e.g., Rumex nepalensis, and related species from the Rheum genus, are used in Nepal and Tibet as a yellow dye plant.
