Sunday, June 17, 2012

Apple #590: Why are Blue Jeans Blue?

Continuing my theme of blue-related topics (later historians will refer to this as my blue period), instead of reaching for some exotic blue thing, i.e., the blue-footed booby of last week's entry, I thought, what about some common thing that we take for granted as being blue?  Like blue jeans?  Why are they blue, anyway?

That's a lotta jeans, and they're all blue.
(Photo from Zoe's Sketch Book)

  • The short answer is:
    • 1. because blue was a popular color when jeans were invented, and 
    • 2. cotton is difficult to dye, but for whatever reason, it doesn't mind indigo.
  • But of course, you know me.  There's more to the story than that, and I can't let it go without telling you the rest.

How Blue Jeans Were Invented
  • OK, so Levi Strauss owned a dry goods store (that means he sold a lot of clothing and fabrics and textiles).  He was originally from Germany, grew up in New York, then moved out to San Francisco to sell stuff to the miners and scads of people going West for the Gold Rush.
  • One of Strauss's customers was a tailor from Reno, Jacob Davis. He was taking Strauss's fabrics and turning them into horse blankets and tents and selling those. 
  • He, too, was born in Europe -- Latvia, to be precise -- then moved with his family to New York, then headed West. This business about both guys being from Europe is important; you'll see why in a bit.  
  • Davis's customers told him their pants kept getting ripped, especially at the pockets, while they were working.  One day, while using rivets on horse blankets, Davis thought he'd try using rivets on his work pants to keep the pockets from getting ripped.  He made some pants like that, and they were a hit with his customers.

Jacob Davis (born Jacob Youphes, from Latvia) came up with the idea for riveted work pants.

Levi Strauss (born Loeb Strauss, from Germany) sold Davis the fabric and had the money to pay for the patent.
(Photos from The Great Idea Finder)

  • Davis wrote to Strauss in San Francisco about his idea, Strauss said it sounded good to him, and he agreed to help Davis file the patent.  The key feature of the pants was that they were like overalls except without the bib-like top -- for many years they were referred to as "waist overalls" -- and they had rivets which were sturdier at holding the garment together.
  • The first pairs of jeans came in two styles, blue denim and brown cotton "duck," which was another kind of sturdy fabric.  The duck never got as soft as the denim so that fell out of favor rather quickly.
  • Denim had been around for a long time -- the history of denim is its own interesting story which I won't get into here -- and Strauss and Davis dyed their denim blue because, as I said, cotton (which is what denim is made of) is difficult to dye, but indigo works with it quite well.  So it was one of the easier choices of colors for denim.
  • Specifically, they used indigo to dye their denim. And as it happens, indigo had been very highly sought-after for a long time.  For centuries, actually.  

Europeans Sure do Love that Indigo
  • Indigo dye comes from the indigo plant, which is a flowering shrub.  The precise name of the plant varies a little depending on where it's grown and what species it is.  There's indigo from India, and indigo from Africa, and another type of indigo from the tropical Americas.
This is the Indigofera tinctoria, which is the type of indigo that grows in India.
(Photo from the Prelude Medicinal Plants Database)

This is Indigofera arrecta, which is the species of indigo that grows in Africa. I couldn't find a photo of this species with flowers, but you can see the difference in the leaf shape. 
(Photo by Bart Wursten, Flora of Zimbabwe)

  • There's also another plant entirely grown in Europe, called woad, which also produces a blue color. It's woad that the Celts used to paint themselves blue, by the way.  Robin Hood's Saxon green was made by combining woad and a yellow dye that came from wild mignonette. But woad's blue is not the same as indigo's blue. Even though Queen Elizabeth I banned indigo in an effort to support the use of woad at home, people still wanted their indigo.
  • For a long time, the only place where Europeans could get indigo was from India.  I'm talking the 1400s now.  People had to sail those dangerous, long-ass freakin' trade routes to India and back to get indigo to Europe and dye their clothes with it.  So you had to be pretty rich to have any garments colored blue, which meant that for a long time way back then, only royalty wore indigo.
  • (Which means, by the way, if anyone gives you guff for wearing blue jeans, you could always retort, "Once upon a time, kings would have killed to be able to wear blue pants like these.")
  • By the late 1500s, the Europeans just had to have their indigo, so folks in India started growing the plants like mad.  There was something of a boom in India over indigo, but for some people that was a bad thing.  Plantations developed and so did slavery.
  • By the 1700s, Europeans had become totally hooked on their indigo, but they were sick of sailing all the way to India to get it. So they started coming up with other ways to get their indigo.  So the Spanish colonists began growing it in Central America and in Louisiana.  British colonists started growing it in the early US colonies. 
    • Actually, the first indigo crop in today's US was started in South Carolina by a 16 year-old girl, Eliza Lucas Pinckney. After her mother died and her father went to Antigua to become governor there, she took over her father's homestead and decided to start growing indigo. Her first two attempts failed but the third one worked. Soon indigo exports from South Carolina took off like wildfire.
    • Indigo might have been the king crop of the south by the time of the Civil War, if the Revolutionary War hadn't happened and people hadn't needed rice more.  Then the cotton gin was invented, which made it even easier to convert cotton from crop to thread, so by that time, if anyone was still growing indigo in the south, they switched to cotton.
  • If the south could have grown the two together, indigo and cotton, things might have turned out very differently for them.  That and if they hadn't gotten into the whole nasty slavery thing.

Detail from a map of the Parish of St. Stephen in Craven County, showing slave laborers harvesting and drying indigo on a plantation.
(Map from Duke University's Special Collections Library section, Slave Voices)

Indigo and Slave Labor
  • Now, when I say the "colonists started growing indigo," what I mean is they had the idea to do it, and they bought the stuff needed to get the crop going, but the people who did the actual work were slaves.  
  • In the Central Americas, it was the native peoples.  Strangely, they kept getting sick and dying from working with the indigo. (Dying while dyeing. It's a pun, but it's not funny.) The Spanish thought, hey, those black slaves from Africa might not be as frail. So they switched to African slaves.
  • Since indigo also grows in Africa, some of the African slaves already knew how to work with it. So they made their own improvements to the cultivation of indigo, and they also improved dyeing methods. But they kept getting sick and dying, too. 
  • As far as I can tell, it wasn't the plants themselves that were making people sick. To get from a leaf or a flower of the indigo plant into a dye that will adhere to a fabric, you have to extract the color from the plant, and then you have to make it water-soluble.  In the process of doing that, at one stage you get something called indigo yellow. It is thought that the indigo yellow by-product is probably the thing that was toxic.
This woman in Thailand is working with natural indigo. Knowing how many people died back in the day from using natural indigo, this photo makes me very nervous.
(Photo from Tammachat Natural Textiles)

  • So in the big picture of indigo, it was becoming more widely available as it was being grown in more places. But it was the Europeans who wanted it and who had the money to pay for it.  
  • So the initial reason for why Strauss & Davis dyed their denim blue is probably because, having worked for years with textiles, they would have known that cotton doesn't mind being blue.  So blue would have been an easy choice, from a manufacturing standpoint.
  • But I also think their origins in Europe have something to do with it.  Because they came from a place where people really wanted to have clothes and garments dyed blue. 
  • So even though Strauss & Davis's work pants were intended for people who were most definitely not rich, they might have assumed that people would want very much to have blue pants. As it turns out, they were right.

From Natural to Synthetic
  • But the fact that people were getting sick and dying from working with indigo, that was kind of a problem. And it was also a problem that the supply of indigo just couldn't keep up with demand.  So some chemists started to figure out how they could make a synthetic indigo.
  • Most of the advanced chemistry at the time was being done in Germany (this is why so many of our chemical and pharmaceutical companies today are based in Germany or have German names). One German chemist named -- get this -- Johann Friedrich Wilhelm Adolf von Baeyer started working on figuring out how to make a synthetic indigo.  That was in 1865.  By 1880, he'd found the answer.

How indigo was synthesized in the 1900s, beginning with naphthalene and using potassium permanganate as the oxidant. 

How indigo is usually synthesized today, starting with benzene and using the now much less expensive sodium.
(Diagrams from Backyard Chemistry)

  • Strauss & Davis patented their waist overalls / blue jeans in 1873. So their blue jeans came out right when the chemists were trying to solve the indigo problem.  It's a total coincidence that shortly after those waist overalls started taking off that a synthetic indigo was found.
  • It took a while before people started buying synthetic indigo.  People didn't believe it was possible to have a synthetic indigo, for one thing, and for another, the molecule looks exactly the same as natural indigo. Some chemists have a hard time telling them apart. But it was the low price and the "superior purity" of the synthetic indigo that finally convinced people en masse that they could get the same or better results from the synthetic stuff.
  • By 1913, BASF, the company for whom Baeyer worked, had sold 4,900 tons of indigo.  That's a lot of blue.  
  • While the first blue jeans were almost certainly made with natural indigo, at some point in the next 40 years or so, Levis Strauss blue jeans were made with synthetic indigo and have been ever since.
  • Today, synthetic indigo is now the most-produced textile dye in the world, largely because of the popularity of blue jeans. In 2002, 17,000 tons of synthetic indigo were manufactured worldwide.

Jeans from Japan, dyed with natural indigo on the left and right, and synthetic in the middle. You can see that the blue of the synthetic is different from the natural, but the two natural indigos also differ from each other.
(Photo by superbored at superfuture)

The Hues of those Blues
  • About the fading.  Natural indigo fades naturally over time.  So it makes sense that synthetic indigo, which looks and acts a lot like the natural stuff, would do the same.
  • Also, the results of dyeing with natural indigo can vary considerably from one batch to the next, depending on humidity, temperature, and so on.  
  • When dyeing with natural indigo, when the dye is watery and you're sloshing the pants around in the vat, it actually has a greenish-yellow color.  You hang up the pants to dry, during which time oxidation takes place, and they turn blue. (As for that photo above in which the wet dye is blue, all I can think is that the dye was exposed to the air long enough that it turned blue even while it was wet.)
  • At any point in the process -- how the dye is extracted, whether it came from an indigo plant grown in India or in Africa or in Central America, how the vat is mixed, how humid it was that day, how sunny it was when the pants dried -- any of those things can have variables, which means the blue color on the pants can be different from one batch to the next.  
  • So it's perfectly in keeping with the characteristics of natural indigo that our synthetically-dyed blue jeans vary in shade from one pair to the next, and that they fade.
Blue jeans are blue, but there are all sorts of shades and hues of blue.
(Photo from A History of American Technology)

Coda in India
  • Remember all those slaves in India who were working on the indigo plantations?  Well, when synthetic indigo became popular, the bottom fell out of the natural indigo market.  Growers in India couldn't get people to buy as much of their indigo as they used to.  So the plantation owners (many of whom were British) started putting the squeeze on their slaves/indentured servants to grow more indigo and to give up a bigger percentage of their yield to the growers.
  • This put a big hurt on a lot of people who were already hurting.  The villages where the workers lived were rife with horrible conditions. At the historic Champaran protest in 1917, the majority of the thousands who turned out to protest were indigo growers. It was during this protest that Gandhi made his first public statement advocating non-violent resistance.  
  • After that protest, Gandhi interviewed over 8,000 indigo workers and published a scathing report about how they had been exploited.  As a result of that report, the bill that was passed reforming agrarian practices in India was part of the beginning of India's victory for independence.
I'm not sure when this photo was taken, but this may have been what the Champaran protest in 1917 looked like.
(Photo from

  • Baeyer won the Nobel for Chemistry in 1905, and his discovery of synthetic indigo was one of the reasons he was awarded the prize.   I don't think the Nobel committee had any idea of the ultimately positive effect his synthetic indigo would have on so many people around the world.

Natural indigo-dyed jeans are becoming popular again, especially in Japan (which has its own history with indigo), which is where these were made. You can buy a pair of these Oni Denim Awa Shoai of your very own for only $685.00. 
(Photo from blue in green)

The moral here seems to be that just because it's got the word "natural" in front of it, that doesn't necessarily mean it's better.

The Great Idea Finder, Blue Jeans History, This Day in History, May 20, 1873: Levi Strauss and Jacob Davis receive patent for blue jeans
BASF, The Chemical Reporter, What makes blue-jeans blue? podcast
The Straight Dope Message Board, Why are blue jeans blue?
Jean M. West, Slavery in America, The Devil's Blue Dye: Indigo and Slavery
superfuture, supertalk, natural versus synthetic indigo
UCLA, Plants and Civilization, Economic Botany, Woad is Me (Isatis)
University of New Brunswick, Outreach Site for the Department of Chemistry, The history of indigo
Plant Cultures, Indigo - history
Sarah Leopold, Sewanee University, Chemistry & Art, A Brief History of Indigo in the United States

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