Jean’s indigo pot at dye day prompted the question: What is indigo? It turns out “indigo” is different depending on where you grew up. There are no fewer than 50 recognized indigo bearing plants grown in the world’s warmer climates. The best quality indigo (Indigofera Tinctoria) is native to India, China, Indonesia and northern parts of South America. It’s a 4-5 foot legume (bean) bush sometimes referred to as “butterfly flowers”.
In a process that has remained the same for over 4000 years, the bushes are cut and the plants are loaded into fermentation vats, where they are weighted down, covered with water, and fermented for 1-2 days. At exactly the right moment (when it tastes sweet) the whole bubbly mass is transferred to another vat where oxygen is added with hours of beating (human or mechanical). Eventually the indigo starts to separate. The excess liquid is drained off and the goo at the bottom is collected, boiled, filtered through cloth, formed, dried and sold off to market for you and I to play with. The work is smelly and laborious. The process can take months and the whole crop could be trashed by a bad day of weather.
Synthetic indigo is a aniline dye. It was developed in Germany. The first work came from a doctor and chemist who wanted to find a use for the disgusting coal tar goo that was piling up at the Berlin Gas Works as a industrial afterthought. He managed to isolate aniline oil, and turn things blue with bleaching powders, but his work was sabotaged and his results were never presented to the directors. Almost thirty years later, another German chemist started his work to synthesize indigo; accomplishing the task in 1878. It contained fewer impurities, the color was constant and manufacture was not affected by weather.
Within a decade, BASF brought synthetic indigo to the word market and changed the fortunes of empires.
2600BC earliest recorded production in China
450BC Herodotus describes it’s use in text
100AD first large scale production in Roman Empire
1498 Britain opens of sea routes to India
1598 France: use of indigo forbidden-dyers had to swear an oath to only use woad
Nurnburg Germany dyers threatened with death for use of indigo, sale of indigo dyed textiles forbidden laws lasted over 50 years, finally abolished as unenforceable
1600 British East India company formed
1602 Dutch East India Company formed
1650’s indigo plantations established in South Carolina
1834 Dr. Ferdinand Runge isolated aniline oil from coal tar-worked in the gas works in Berlin. The process was successful,but his work results were sabotaged.
1878 Von Baeyer synthesizes indigo (it took 13 years starting in 1865)
1897 first commercial production BASF/Germany
1895-96 India exports 18,700 tons natural indigo, Germany imports 20 million marks worth of natural indigo
1913-14 India exports 1,000 tons natural indigo, Germany exports 50 million marks worth of synthetic indigo
Denim: a twill cotton fabric originating from Nimes France. The original name was serge de Nimes, which our tongues eventually shortened to denim (denim info from Weavers Guild of Greater Cincinnati/Weaverbird News)