This section is from the "A Complete Dictionary of Dry Goods" book, by George S. Cole. Also available from Amazon: A complete dictionary of dry goods and history of silk, cotton, linen, wool and other fibrous substances,: Including a full explanation of the modern processes ... together with various useful tables.
Woad. A plant formerly cultivated for the blue coloring matter derived from its leaves, but is now used only with indigo as a ferment in the vat. It is inferior to the coloring matter derived from indigo, the latter having entirely superseded it for dyeing purposes.