Design by Nature: Producing Blue Dye From Woad Plants

Design By Nature is an ongoing GC series in which Garden Collage explores aspects of modern clothing design that were inspired by plants. This week, GC investigates one of Europe’s oldest sartorial traditions: how blue dye is produced from the Woad plant (Isatis tinctoria) — it takes a lot of work.

Producing blue dye from the Woad plant (Isatis tinctoria) is a trade that dates back to the neolithic period, 5 to 10,000 years ago. Woad is a flowering plant native to the Mediterranean occasionally known as Asp of Jerusalem– it’s a cousin of broccoli and cauliflower that originated in Turkey and the Middle East, before spreading to Europe where textile makers picked and crushed the leaves into balls, which turned the workers’ hands black.

The process of producing dye from Woad was a smelly job. The balls were dried and ground into powder which had to be watered and allowed to ferment and oxidized– a process called “couching.” When the woad was dry, the powdered woad was packed up and sent to the dryer, who poured hot water over the substance and mixed it with urine (yes, human urine– which was stored in a vat whose pH was maintained by the male workforce). Today, those interested in natural, hands-on dying have replaced the urine with diluted ammonia.

This mixture was left to ferment for several days up to a year– a process that yielded a horrible, sulfurous odor. The woad mixture, however, produced a lovely shade of blue that was the only light-fast blue dye in Europe until the introduction of indigo from Asia, which found it’s way into Europe throughout the Middle Ages (as early as 1140 in mainland Europe and 1276 in London). Workers would lower garments into a vat of dye very slowly, careful to avoid air bubbles that would cause the fabric to dye unevenly. Then, they would pull them out quickly, and when air hit the garment it would oxidize from yellow to green to blue so rapidly that, as one modern blogger has phrased it, the process was “almost like magic.”

Woad was used in England to dye the coats of military officers and policemen as late as the 1930’s; it was also prized by Napoleon, who used it to dye his army’s uniforms. Documents from the period, meanwhile, note that Woad has antiseptic properties and may have been used to heal battle wounds, which at the time gave it dual functionality and made it the cornerstone of France’s economy.

The ancient Egyptians also used woad and indigo, as dyed cloth dating back to 2500 BC has been found among mummy wrappings. Woad dye was likely not used in common clothing in Egypt until 300 BC., since most Egyptians wore linen, which is a difficult fabric to dye (as a result, color was used sparingly, mainly in the border of fabrics). Today, makers of traditional textile honor the dye’s legacy by hosting workshops on Woad extraction– a popular craft activity in the UK.