The Chemical Era

Discovery of Synthetics    Indigo in 20th Century Fashion    Cottage Indigo Industries Today      and the Blues 

Efforts to bypass the British monopoly on indigo led to the German development of synthetic indigo dyes, and, ultimately, to the development of aspirin. However, the ensuing German monopoly on synthetic indigo contributed to the death of tens of thousands of French soldiers in World War I. Production of synthetic indigo may also have contributed to countless deaths from cancer. In the last eighty years these synthetic dyes helped popularize blue jeans and Mao suits. However, indigenous knowledge of the art of indigo dyeing persists in tropical regions, awaiting a renaissance from the current interest in natural materials.

Discovery of Synthetic Dye


indigo reduction 

In 1859, the first year of the Bengal indigo disturbances, the world's first modern synthetic dye (purple) was distilled from coal tar. The German chemist August Wilhelm Hofmann researched the constituent parts of a byproduct of the coal gasification process and discovered how to convert benzene into dyestuff.  Hofmann dubbed these synthetics  “aniline” dyes, named after the Sanskrit “anil” for the elusive indigo blue. 

In 1865 the German chemist Johann Friedrich Wilhelm von Baeyer began to research indigo and soon discovered indole and the partial synthesis of indigotin. Indigo had fascinated him since his childhood, and in 1878 he developed a full synthesis of indigo. Other chemists from Germany traveled to England to study in the British dye industries, and returned home with updated scientific and technological ideas. By 1897 the German company BASF (Badische Anilin und Soda Fabrik AG) had developed a method for industrial scale production of synthetic indigo dye that radically transformed the world market for natural indigo. 

The British monopoly on indigo from India became meaningless as natural indigo soon became almost completely replaced by the synthetic German substitute in the manufacturing of textiles. In 1904 Germany's export of synthetic indigo was valued at over 25 million marks, and the price of Bengali indigo had fallen to one third of its former price.[1] Technology had produced access to industrial quantities an indigo dye without coerced labor.

Early Aspirin marketed by Bayer 

This search for synthetic indigo dye contributed to the emergence of applied organic chemistry. In 1880 the German dye-manufacturer Bayer & Company began to apply scientific expertise to the profitable business of producing pharmaceuticals. The first product they produced and marketed, acetophenetidin, was derived from a by-product created while making synthetic indigo. In 1897, a German chemist named Felix Hoffmann, a student of Adolf von Bayer's, while researching a way to reduce the undesirable side effects of salicylic acid, employed another intermediary by-product of dye synthesis to create acetylsalicylic acid, or aspirin. (He invented heroin two weeks later.) In 1905 the Nobel Prize in Chemistry was awarded to Johann Friedrich Wilhelm von Baeyer “in recognition of his services to the advancement of organic chemistry and the chemical industry, through his work on organic dyes.” His childhood fascination with the indigo dye process had led, by the turn of the century, to new drugs being developed and produced in unprecedented quantities.   In the 1930s, chemical research into dyestuffs and their intermediaries led to the discovery of sulfonamide drugs. Dye manufacturers and doctors interacted in a producer-consumer relationship that profitably led to the creation of better medicines.
In 1877 BASF helped formulate a patent law that protected their synthetic indigo profits. Whereas slavery produced indigo profits in the Americas, and financial structures perpetuated indigo profit in Bengal, patent law created wealth from synthetic indigo in the Age of Chemistry. By 1914 BASF was producing 80% of the worlds synthetic dye. Indian exports of natural indigo fell from 187,000 tons in 1895 to 11,000 tons in 1913.[2] The long-suffering farmers in Bengal switched to the production of a more lucrative export crop, opium. The story of the industrialization of indigo thus involved exploitation of labor, capital, and technology.
At the outbreak of World War I, supplies of synthetic indigo dropped from the market. German industries needed the chemists and their chemicals for the manufacture of explosives. The decline of woad and natural indigo production, precipitated by the advent of the cheap synthetic substitute, meant that the allies had no source of blue dye for their soldiers’ uniforms. In France, this shortage was particularly acute. After the Haitian Revolution, Napoleon had foreseen the consequence of dependence on foreign imports and tried to resuscitate woad production. However, it never became productive enough to meet military demands. In 1829, the blue pants of French soldiers were replaced with bright red pants dyed with madder, grown in Provence. Unfortunately, this audacious color transformed the French soldiers into visible targets on the battlefield. Yet, the war minister declared, “to do away with all that is colorful, all that gives the soldier his strutting air, to go against French taste...the red pants, c'est la France.”[3]  French soldiers were stuck wearing bright red pants until after 1915, by which time they had already suffered over 980,000 casualties.

Synthetic Indigo Today- Dystar

Trade protections continue to ensure wealth for select synthetic indigo producers. In 2001 BASF merged its textile dye operations with Bayer and Hoechst into Dystar.  (These same three companies also merged on the eve of  WWII to create IG Ferben, producer of the notorious chemical Zyklon-B. After the war the allies re-divided, and indemnified, the companies.) Dystar is now the world’s largest supplier of textile dyes. In 2001 they reported over 1 billion DM worth of sales. The annual production of synthetic indigo was then estimated at 22,000 tons of dyestuff.[4]  In 2006, Dystar sought to defend its patent on Indigo vat dye solutions in both US and Brazilian courts. However, Dystar’s patent, originally issued to BASF, was found to be invalid.[5]
In 1999, 2000, and 2001 the United States International Trade Commission, in an effort to protect the sole domestic producer of synthetic indigo, Buffalo Color Corp, issued sanctions against China for dumping bulk quantities synthetic indigo (and aspirin in the same shipments) onto the market at “less than fair value”. However, despite these protections, BCC went bankrupt by 2005 and the commission revoked the anti-dumping order in April of 2006.[6] Dystar opened a $55 million dollar plant in Nanjing the following October.

Environmental Concerns

Image from USGS Amphibian Monitoring Site 

Environmental issues related to the indigo dye industry date back to antiquity when the Greeks required all dyers to move their odoriferous workshops to the edges of the city. In the 1970s attention began to focus on the pollution produced by the synthetic dye industry. Synthetic indigo smells like rotting fish, ignites readily, and is toxic if inhaled as a vapor. To create synthetic indigo dye, benzine is treated with corrosive chemicals such as hydrogen cyanide. The production of benzidine dyes are now widely associated with bladder cancer. Furthermore, the hydrosulphites used in the transformation process are environmentally harmful. There is concern that their presence in wastewater may cause DNA damage to amphibians.[7]
In 2007 the United Nations Environment Programme awarded a grant to a group in India to promote the use of natural dyes in the textile industry. Natural indigo currently accounts for less than 1% of the total indigo dye market. However, a resurgent interest in natural products suggests that its use may be on the increase. Several organizations in Bangladesh are seeking to produce high quality natural indigo in an environmentally sustainable manner. With populations showing more interest in natural fibers and dyes, consumer enthusiasm for blue may yet lead to the large scale production of indigo again.

Synthetic Indigo in Fashion

In the 1920s uniforms of policemen and postmen joined sailors and soldiers in adopting blue as a standard color. In the 1930s the navy blue blazer replaced the black suit in business circles. Arguably the most mythic article of indigo dyed clothing in America, blue jeans entered this world in response to the California Gold Rush. To meet the demands of miners, Levi Strauss produced durable overalls and pants with fabric from Genoa (Genoese gives us the word jeans) starting in 1853. In the 1860s his company began to use serge de Nimes (or denim), a strong cotton fabric dyed with indigo. However, since the denim was so densely woven, it did not completely absorb the indigo dye, and thus the color wore off in response to the rigors of use. Faded blue jeans became a symbol of the rugged American frontiersman.

blue jeans

Today, it would be impossible to grow enough natural indigo to dye the more than a billion pairs of blue jeans produced annually. Synthetic indigo has been extensively used since the 1920s. However, when synthetic dyes were introduced, they made the pants more colorfast, and consumers were not pleased; jeans companies had to introduce new chemicals so that the synthetic dye could mimic the flaw of its natural indigo precursor. In 1935 Vogue magazine accepted its first ad for blue jeans, and this indigo clothing entered the domain of the chic. After World War II, James Dean transformed faded blue jeans into a symbol of youthful discontent.[8] Just as indigo dyed cotton blurred social distinctions in eighteenth century Britain, indigo jeans blur social distinctions today.
Synthetic indigo entered the realm of revolutionary chic with the advent of the Mao suit. In 1949 Mao Zedong, resisting pressure to conform to the black business suit culture of western leaders, chose to wear a dark blue cotton tunic that resembled the indigo-dyed tops and trousers common to peasants of both genders.[9] Enormous quantities of synthetic indigo dye had to be used to produce similar outfits for the population of the newly communist nation. Worn extensively during the Cultural Revolution, the ubiquity of indigo blue was seen within China as a symbol of proletarian unity, whereas within the West it was seen as a symbol of cultural homogeneity imposed by a socialist state.

Mao Suit from 1970s. From Powerhouse Museum Collection 


Natural Indigo Production Today

In certain tropical areas conducive to natural indigo production, synthetic dyes never completely displaced indigenous knowledge of the uses of indigofera. The balance between local production and consumption of the dye helped to keep these areas from falling into the web of global trade networks in the early modern period. The inability of European powers to assume control of indigo producing lands and labor kept the cottage indigo industries of these regions independent.
In Indonesia, artisans are famed for their production of resist dyed indigo fabrics. A wax or some other substance is patterned on the fabric and the fabric is immersed in a vat of dye. Since indigo dyeing only requires tepid water, there is no danger of the wax melting as would happen in other dye baths. Furthermore, repeated dipping changes the hue, offering versatility in blue to black color selection. The Javanese term Batik is associated with this hot wax resist dye method. Other places known for their use of batik include Japan, Vietnam, Thailand, India, Sri Lanka, Turkistan, and countries in West Africa. Although other dyes can be used with this method, the earliest known examples of resist dye printed fabrics used indigo.
Indigo is the most frequently used color on Javanese Batik. By the early seventeenth century Central Java was famous for their production of soga batiks in which intricate indigo blue patterns were drawn on a crème brown fabric made from the soga tree bark. These indigo and cream batiks were highly valued in the inter-Asian trade with the Chinese as well as the European trade conducted by the Dutch. Indonesian women are able to draw very precise lines in hot wax by using a bamboo-handled instrument with a copper reservoir and small spout. In the mid-nineteenth century, in response to competition from Dutch machine produced imitation batik, Indonesians invented a method of stamping hot wax onto fabric.[10]

printing by hand 

Once the Indonesians developed the faster method, the Dutch sought to off-load their imitation batiks on the Gold Coast of Africa where Dutch missionaries, mercenaries, and traders already had a taste for the Javanese styles prints. The popularity of this style spread in the general market, and the Dutch began to produce “African prints” to compete with the local market. To this day there are still Dutch and British companies that manufacture imitation wax print fabrics for the West African market. Until the mid-1980s, all of these were dyed in indigo.
In West Africa, the Yoruba of Nigeria are also famous for their use of indigo resist dye “batik” methods, called adire eliko. There, a starchy resist paste made of cassava flour is applied free hand with a comb, chicken feathers, or sticks. As in Java, in response to competition from European machine produced imitation batik imported in the mid-nineteenth century, the creative process changed; the use of stencils and the involvement of men were introduced to the industry. Still, in the 1930s almost half the population of Yorubaland was involved in the indigo industry, producing 200,000lbs sterling worth of cloth annually.[11] In the 1990s most of the millions of meters of cloth produced for the home market in Ghana's wax-print factories were dyed indigo patterns. In Ghana, indigo is considered the color of love.
In Yorubaland the women are in charge of dyeing, and girls are taught the indigo dye process from a young age. (In the north, the Hausa dyers are Muslim men.) During the dyeing process, Yoruba women make offerings to the Goddess Iyta Mapo, the divine protector of women.[12] Banu Yoruba women themselves weave “marriage cloths” from indigo dyed, hand-spun cotton. Of the thirteen specially named and patterned cloths kept in the marriage basket, only two lack indigo dye.[13] In Sierra Leone, where women dyers can charge a fee for training an apprentice, it is said that hands that are always black with dye can identify a free woman.
In both Mali and Sierra Leone the status of dyers is very high. Indigo dyers in Mali belong to the caste of artisans that include sculptors and praise singers. Indigo is considered to have a powerful but potentially destructive spiritual energy.

The Blues, Blue Notes, and Mood Indigo

The color blue has often been associated with death in indigo producing regions. This may reflect an understanding of the toxic effects of dye production. For the Ancient Maya, blue was the color associated with human sacrifice.[14] In Egypt and Syria warrants for execution are printed on indigo dyed paper.[17] In West Africa, burial cloths are traditionally dyed indigo blue, and in Nigeria women of certain ethnic groups wear indigo blue head cloths at funerals.[15] Tamil women call their laments nilappaddu, or dark blue songs. Women in Turkestan, Palestine, and India wear indigo blue when in mourning. In Indonesia songs of lament express indigo’s relationship with death.[16]  In the West, people call melancholy songs, “the blues.”
“Blue notes,” notes that veer from major to minor scale, are common in Islamic influenced West African music. This expressive style traveled with slaves to the Americas where the lowered third and fifth, with dominant seventh, transformed a major scale into what is now called “the blues.” In the 1920s, the blues migrated from the rural South to northern cities as African Americans sought urban job opportunities; there the blues were transformed into jazz. “Mood Indigo” written by Duke Ellington in 1930, is arguably one of the most famous jazz compositions.

Lyrics to Duke Ellington’s Mood Indigo
You ain't been blue; no, no, no.
You ain't been blue,
Till you've had that mood indigo.
That feelin' goes stealin' down to my shoes
While I sit and sigh, "Go 'long blues".
Always get that mood indigo,
Since my baby said goodbye.
In the evenin' when lights are low,
I'm so lonesome I could cry.
'Cause there's nobody who cares about me,
I'm just a soul who's
bluer than blue can be.
When I get that mood indigo,
I could lay me down and die.

Duke Ellington at the Hurricane Club 1943. Photo by Gordon Parks 

 To see & hear Duke Ellington playing Mood Indigo, click here





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[1]  From a speech given by Professor A. Lindstedt, President of the Royal Swedish Academy of Sciences, on December 10, 1905. Nobel Lectures, Chemistry 1901-1921, (Amsterdam: Elsevier Publishing Company, 1966)
[2] Christopher Freeman, The Economics of Industrial Innovation. (London: Pinter, 1997), 90
[3] Michel Pastoureau. Blue: The History of a Color (Princeton: Princeton University Press, 2000), 160
[4] T.Bechtold et. al., “Process balance and product quality in the production of natural indigo from Polygonum tinctorium Ait. applying low-technology methods” Bioresource Technology, Vol. 81, No. 3, February 2002, 171-177
[5] “Battle for the Blue” IP Frontline, Oct.11, 2006
[6]  Stephen Koplan et. al. Synthetic Indigo From China. Investigation No. 731-TA-851. Publication 3846, (Washington: US International Trade Commission, 2006)
[7] Sanjida O'Connell, "Harming the Environment: Jeanie Greenie", The Independent, 10, August, 2006.
[8] Pastoureau, Blue, 192
[9] Verity Wilson, "Dressing for Leadership in China: Wives and Husbands in an Age of Revolutions (1911-1976)"  Gender & History 14 (3) , 608–628
[10] Jenny Balfour-Paul, Indigo (London : British Museum Press, 1998), 151
[11] Ibid., 155
[12] Anne Varichon, Colors: What They Mean and How to Make Them (New York: Abrams, 2006), 186
[13] Joanne B. Eicher, Dress and Ethnicity: Change across Space and Time (Washington, D.C. : Berg, 1995), 123-125
[14] Balfour-Paul, Indigo, 207
[15] Ibid.,186
[16] Ibid.,181

[17] Jenny Balfour Paul, Indigo in the Arab World, (Richmond, Surrey: Curzon, 1997), 157