While at the Oxford Guild, a lady asked me about the difference between indigo and woad. This is a good question as the difference is really one of name rather than dye, as the blue dye in woad is the same as the blue dye in indigo, so woad is just another source of indigo-blue dye. Woad was, and still is, the native European source of indigo blue dye. The name “indigo” is usually used to refer to species of Indigofera, although it may also refer to one of the many other sources of indigo blue dye, such as Polygonum tinctorium from Japan, Strobilanthes flaccidifolius from China or Lonchocarpus cyanescens from Nigeria. In fact, I suppose the term “indigo” tends to refer to all sources of indigo blue dye, except for the blue dye from woad. This is confusing as the blue colouring matter in woad is the same as the blue colouring matter in “indigo”, but the dye is much less concentrated in woad leaves, which is why “indigo” eventually largely replaced woad in Europe. It would make things clearer if we referred to woad-indigo to distinguish it from indigo-blue from other sources. In England, until the 1930s a law demanded that some woad had to be used in the indigo blue dyeing of policemen’s uniforms, presumably to preserve the tradition of woad dyeing & to protect the livelihoods of woad farmers.
Today, the farming of woad on a commercial scale has been started again, largely through the efforts of one farmer in Norfolk, Ian Howard, who has made a valuable contribution towards the revival of one of our traditional dyeing techniques. For more information, click onto the link to Ian’s website.