Indigo Paper3

7/29/2019 Indigo Paper3

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Indigo DyeingBantiarna Brighid Anraith

Copyright 2007

Blue dyes from Plants

There is only one known source of natural blue dye used for clothing, a natural chemical calledindigotin.1 Ancient and Medieval writings record a number of plants which will produce this blue

colour; in fact, there are over 500 plants that can be used to make indigo dye.2

The Plants

The most common source of indigo is from plants in the genus Indigofera, native to tropical climates,though not all indigofera contain indican, the indigo-precursor in Indigo-dyeing plants.Indigofera

tinctoria, also known asIndigofera sumatrana, is the species most commonly used in Asia and India.Indigofera suffructiosa was used in Central and South America. Indigo is a member of the legumefamily and related to peas and beans.

In Northern and Western Europe, being a temperate climate and unsuitable to grow indigo, dyers used

woad (Isatis tinctoria), part of the mustard family, and distantly related to cabbages. Woad is native tosouthern Europe, but can be cultivated in more northern climates.

Chinese and Japanese dyers, also living in a temperate climate, used dyer's knotweed (Polygonumtinctorum), also known as Chinese Indigo, belonging to the buckwheat family, a plant not native to

Japan, but brought from China in the 5th or 6th century CE. These plants also produce indican, but in

much smaller quantities.

History

Indigo dyeing in the Western world has been traced back to ancient civilizations in Mesopotamia,

Egypt, Greece and Rome, including a garment found in Thebes dating to c. 2500 BCE3 and a cuniform

tablet from the 7th century BCE, found near Babylon, describing a recipe for dyeing wool lapis-coloured by repeated dipping4. India, China, and Japan, have used indigo as a dye for centuries,

creating elaborate patterned cloth through both dyeing and resist-printing.

The oldest indigo dyeing centres are believed to be in India. In the Greco-Roman period, it was theprimary exporter of indigo dyes to Southern Europe. Herodotus (writing around 450 B.C.) describes its

use in the Mediterranean area. During the Crusades, indigo became one of the highly prized spices

aquired in Cyprus, Alexandria and Baghdad, at the end of the trade routes from the India and the Far

1 Huxtable2 Emmett3 Mattson4 Scott


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East. 5 Marco Polo talks about the production of the dyes in his Travels.6 But because these dyes had

to travel through many lands on their way to Europe, suffering from heavy export duties in Persia, the

Middle East, and Greece, indigo-derived blue dye was rare in Europe during the earlier part of themediaeval period, and most blue in the rest of Europe was from woad, which was cultivated in northern

Italy, southern France, and parts of England and Germany.7

In 1498, Vasco da Gama, a Portugese explorer discovered a sea route to India. This allowed for directtrade with indigo producers in India, reducing its cost, and increasing its availability. Indigo flooded

into Europe through ports in England, Portugal and the Netherlands,and quickly over-took the use of

woad due to its ability to produce clearer, brighter blues. Not unnaturally, those area which had madetheir fortunes from woad, sought to stem the destruction of their industry by imported indigo, and in

1598, both France and Germany banned the import of indigo, and dyers were forced to swear, at risk of

death, not to use it.8

In Asia, blue dye has been used since the Zhou period in China (1045-771 BCE). Most often the

source of the indigo dye is Dyers Knotweed (Chinese Indigo). In Japan, blue dye was used early on,

but it was a native dye known asyama ai (Mountain indigo) that was used in a technique calledrubbed blue, created by rubbing the leaves directly onto the fabric. Because this did not bond the dye

to the fibres the colour faded quickly and ran when washed. When Chinese Indigo (known in Japan as

tade ai) was first introduced in 5th or 6th century CE, it was used the same way as the Mountain Indigohad been, until vat dye technology was introduced as well.

Blue is a popular colour in Japan because the colour is considered auspicious. It also hides dirt well,has some insect-repelling qualities and is one of the few natural dyes that dye cotton easily, an

important consideration since silk was expensive and at some points forbidden to the common people.

It is still popular today as a dye for the cotton summer robes calledyukata. A raw indigo dyeingprocedure, uses fresh leaves in the dye bath itself was developed, but the colours are not nearly as fast,

and fermentation vats were preferred.9

Synthetic Indigo was first developed c. 1880 and quickly overtook naturally sourced indigo for dyeingas the synthetic indigo was cheaper, clearer and more consistant due to its lack of natural impurities. It

does not adhere as well to fibres as natural indigo, however and will start to wear off sooner.

Producing the Dye

The indigo plant itself does not produce the blue dye. Indican, the indigo-precursor in the indigo plantand in dyers knotweed, which is a by-product of the plants metabolic process meant to resist insect

attack10, is a colourless, glucose-based substance, and during the fermentation process that results in a

usable dye, a bacterial enzyme created in the vat consumes the glucose, leaving indoxyl. The indigo-

precursor in woad is isatan-B, which also hydrolyses in the fermentation process to form indoxyl, twomolecules of which bond together with an oxygen molecule during oxidation to form indigotin. It is

from this substance the dye powder is made. Chemically, the two dyes are identical. Any

5 Mattson6 Polo7 Mattson8 West9 Wisniewski10 Emmett


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discrepancies in the dyes from different sources are a result of natural impurities in the dyes, and in the

quality of the crop they were derived from, and the skill of the dye producer. 11

In India, the traditional method of producing blue dye from indigo plants is via giant fermentation

vats.12 These vats, usually brick, lined with cement can be as much as 400 square feet, and are usually

arranged in rows, with the bottom of each vat roughly even with the top of the next, connected by

drains.

Indigo is harvested starting at 4-5 months after sowing, and can be re-harvested at 3-4 month intervals.

The plant produces usable leaves for 2-3 years, after which the plant may live but the dye produced isdistinctly inferior.13

Bundles of freshly indigo plants are placed in the first vats, and water is poured over them. Sometimeslogs or other weights are used to hold the plants down. The plants are steeped until fermentation has

almost ceased, which can take up to a day and a half. During this process, the indican is hydrolysed

into glucose and indoxyl, the glucose being consumed by the fermentation process. It has to be

carefully timed, as over-fermentation can ruin the batch, so this is usually controlled by an experienceddye-maker. When the liquor is dark blue and sweet to the taste, the indoxylhas been extracted from the

plant and is ready to be turned into indigotin.

The liquid is then drained off into the next vat, where men standing in the vat agitate it with large

paddles, to oxidize it, adding the oxygen bond to the indoxylmolecules and thereby creating indigotin.

The colour changes from dark blue to a yellow-brown, and the indigotin begins to separate into flakes,which are then allowed to settle to the bottom. A drain set into the vat above the sediment level drains

off the liquid to stop the fermentation process. Sometimes the resulting run off is drained into a third

vat and allowed to settle again to maximize the yield of the crop. The remaining indigo pulp is heatedto remove impurities, filtered through cloth and pressed to remove as much moisture as possible. The

solid mass is then cut and dried, ready to be transported to the dyer.14

In Europe, woad dye was produced by fermentation as well, though the leaves were dried beforefermentation. The young leaves of the woad plant were picked (once the leaves turn blue, it is too late

to produce dye from them), crushed and hand-kneaded into balls, which were then dried and stored

until the dyer needed to use them. When more dye had to be produced, the balls were ground intopowder and piled up in layers in couching houses, where the layers were made wet and allowed to

ferment for two weeks, causing the isatan-B (the sugar-bearing molecule) to break down into indigotin.

Woad fermentation is particularly foul-smelling, as woad plants contain sulphurous chemicals, whichmay explain why Queen Elizabeth I famously ordered no woad dye to be produced within 5 miles of

any of her homes. After the woad had been couched, it was formed into cakes and sent off to the dyers.

Dyers knotweed was processed in a similar fashion to woad. After the rainy season was over, the first-cut began. The plants are cut and dried on both sides in the sun, then cut into smaller pieces. While

this was happening, the farmers would continue tending the fields and a month later a second harvest

occurs. The leaves, once dry, are placed in straw bags to preserve them until the fermentation processis begun.

11 Huxtable12 Maiwa, video documentary13 Kew Gardens14 Maiwa, video documentary


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In the fall, an auspicious day is chosen to begin process of creatingsukumo (the fermented leaves). The

first-cut leaves are place in fermentation beds and mixed with water to a height of about a metre. Every

five days, the fermenting leaves are sprayed and mixed, then sifted with wooden rakes until they regaintheir original height. The whole process is repeated up to thirteen times, with the second-cut leaves

added during the fourth sifting process. By the twelfth or thirteenth sift the leaves are placed on a

screen to help them ferment evenly. As it is important to keep the leaves warm while fermenting, the

sukumo is kept covered by straw mats. At approximately 100 days after the fermentation begins, thesukumo is packaged up in straw bags in specific weights and sent on to the dyers.15

Using the Dye(note: as Indigo and Woad at this stage are identical, these methods can be used for both)

Traditional Fermentation Vats

Indigotin is more properly called a pigment rather than a dye, as it is insoluble in water or alcohol, and

does not dye the fabric, but lies on top of it. To dye with indigo, the indigotin must be reduced to awater-soluble substance, causing the indigotin to become leuco-indigo, or indigo-white, which appears

a greenish-yellow in the vat. In the reduction process the reducing agent creates indigo white bycausing the indigotin to lose the oxygen bond between the two indoxyl molecules.16 When the fabric isspread out in the air, the indigo-white reoxidizes, and returns to its insoluble blue form, remaining

trapped in the matrix of the fibres. Indigo is a ring dye; a dye that only penetrates the outer layers of a

thread or fabric, leaving the core undyed.

While different ingredients are used by different cultures, the essential process for starting and using a

fermentation vat is the same. The vat must be alkaline, with a pH of approximately 10.5. This

alkalinity may be produced with various substances: lye, stale urine (ammonia), soda ash, lime, potashor ammonium carbonate (bakers ammonia or smelling salts). The reduction of the indigotin to indoxyl

can use a number of different substances as well: stale urine (urea), bran, madder, sake, crushed cane

sugar, Karo syrup, and dates. These substances caused the composting in the vat, creating bacteria,which produces hydrogen, and removes oxygen from the vat.

Fermentation vats are tricky, as fermentation continues so long as there is food for the bacteria. Over-

fermentation is a problem, and will ruin the vat. The vat must also be kept relatively warm, though notnecessarily as warm as when in use, so that the bacteria do not die off. Recipes for fermentation vats

often suggest exhausting the dyestuff in the vat before closing the vat, if it is going to be left unused for

any length of time. The initial fermentation takes about one week, reactivating it by adding newdyestuff and reducing agents will take 3-4 days.

One of the most common ways to accomplish this reduction was to dissolve the indigotin in stale urine.

This fermentation in urine usually takes about a week, during which the vat must be kept warm. Theurine provides nutrients to the bacteria which reduces the indigotin, and also the ammonia which causes

the vat to become alkaline. The process is complete when the solution is a greenish-yellow, and thereis a copper or iridescent blue scum on the top.

Using urine has disadvantages, not the least of which is the smell! The urine-vat is one of the smelliestfermentation methods. It does have some advantages, however. Urine is readily available to anyone,

15 Wisniewski16 Huxtable


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(everybody pees!), is milder on protein fibres, and is generally the only thing you need to add to the vat

besides the indigo.17 Poor fermentation can be fixed with additional sugars to feed the bacteria, and

ammonia can be used to increase the alkalinity.

The fabric or thread to be dyed is presoaked in water or urine, then gently lowered into the vat.

Because introducing oxygen into the vat reverses the reduction, it is best to keep the fabric tightly

bundled until underwater, and then opened. Fabric is left to soak for anywhere from 20 minutes to 24hours, then pulled out carefully, squeezing the excess fluid off, gently and as near to the surface of the

dye solution as possible. The fabric should then be spread out on a line or bush and allowed to air for

about 20 minutes, before being reintroduced to the vat.

The blue achieved by the dyer depended on the strength of the dye solution and the number of times the

fabric is dipped into the vat. A single dip in the vat produces a pale blue, while repeated dips canproduce a blue so deep it is almost black. In fact, some mediaeval blacks were produced by repeated

indigo dips, combined with the use of tannins or iron mordants. In several dye centres lists of names

for each shade of blue created at each additional dip were given specific names, some of which are still

in use today, like Royal Blue and Navy Blue. It was these repeated dips that made blue fabric sotime-consuming, and therefore so expensive.

Some Fermentation Vat Recipes:

Recipe #1

8 ounces finely powdered indigo4 ounces wheat bran

4 ounces madder

1 pounds soda ash (washing soda)4 gallons water

Put ingredients in a large pot or bucket, and keep at 30 C, stirring well, but gently each day until liquid

is yellow-green and has a blue-copper scum on top.

Recipe #2

1 gallon urine (allowed to go stale)1 ounce indigo, powdered, in a fine mesh bag

Put mesh bag of indigo in vat with urine, and set vat in a warm place (in the sun, but protected fromdirect sunlight). Twice a day rub the bag between your fingers in the vat to help release powder from

bag. When liquid turns greenish-yellow vat is ready to dye.

Recipe #31 tablespoon yeast

1 cup warm water

1 rounded tablespoon sugar2 level tablespoons indigo powder

cup non-sudsing ammonia

17 Liles


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Combine yeast, water and sugar in a container and let stand in a warm place 2 hours. Mix indigo with

ammonia and let stand 2 hours. Add indigo mix to yeast mix in a half-gallon container, fill to top with

warm water and seal with a non-rigid seal (like saran wrap) and allow to stand several days. Vat isready to when the liquid has turned yellow.

Note: Some synthetic indigo dyes do not reduce properly in fermentation vats. It is recommended to

always use natural indigo in fermentation vats.

Chemical Vats

Chemical vats are a modern adaptation of indigo vats. A typical chemical vat uses caustic soda (lye) as

a reducing agent, and sodium sulphite, (e.g. Thio-Urea Dioxide), or sodium hydrosulfite to provide the

alkalinity.

The chemical vat has a few advantages over traditional fermentation vats, not the least of which is the

smell! A chemical vat requires only a few hours to become active, and can be allowed to cool when

not in use and left unused for a considerable length of time (my chemical vat was left approximately ayear at one point). Warming and the addition of the reducing agent can easily reactivate it. Chemical

vats can also be made much stronger than fermentation vats, allowing for much quicker build-up of

colour.

However, this speed, ease and olfactory relief come at the price of end results. Lye is extremely caustic

and damaging to fibres, shrinking cellulose and eating protein fibres (and protein human skin cells). Inthe correct amounts needed for dyeing with indigo, it should neither shrink your cotton and linen, nor

eat your wools and silks, though you do need to rinse them very thoroughly to prevent damage to the

fibres.

Another problem is that while the first few dips in a chemical vat do create a deeper blue each time,

after only a few the differences between dips become much less noticeable, as the thio-urea is a

discharging (bleaching) agent and discharges the indigo the vat previously deposited. A true, even, anddeep blue is very difficult to achieve. A very strong dye solution may give you a dark blue, but result

in a much less even, beautiful colour. Thio-Urea also makes over-dyeing difficult because it may

discharge the previous colour. Always dye with the indigo first.

Also, while a fermentation vat is used at its normal temperature, and thus is gentle on sensitive fibres

like wool, the suitable temperature of a chemical vat for cellulose fibres is 90-100 F; the temperaturefor protein fibres is 120-130 F.

As in fermentation vats, the fabric or thread to be dyed is presoaked in water, then gently lowered into

the vat. Again, because introducing oxygen into the vat reverses the reduction, it is best to keep thefabric tightly bundled until underwater, and then opened. Fabric does not need to be left to soak for

more than a few mintues. Pull out carefully, squeezing the excess fluid off, gently and as near to the

surface of the dye solution as possible. The fabric should then be spread out on a line or bush andallowed to air for about 20 minutes, before being reintroduced to the vat.

Chemical Vat Recipes:

Recipe #1

Stock Solution:


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1-1/2 Tsp lye (caustic soda), dissolved in hot water

Add 2-4 tsp finely ground indigo dye and stir for 2 minutes.

Add 1 tsp thiourea dioxide and stir for 1 minute.Put a lid on the container, and place in a warm spot for 1 hour

Solution should change from opaque blue to translucent yellow-brown.

Preparing the Vat:Put 5 gallons of hot water in a plastic bucket

Add 1/8 tsp of lye and stir until dissolved.

Add 1 tsp thiourea dioxide and stir until dissolvedCover vat and allow it to reduce for 15 minutes

Carefully lower jar of stock solution into vat and pour out contents.

Stir gently and allow to reduce for 1 hour.

Possible substitutions from the grocery store: Lye may be replaced with washing soda (in the laundry

detergent aisle, and Thiourea Dioxide can be replaced with Rit Colour Remover.

SafetyALWAYS WEAR GLOVES!!! Fermentation vats contain bacterial agents, which may cause a

reaction (and fermenting urine is just icky, even if its your own!). Chemical vats contain caustic

chemicals, which will eat you skin (or at least the top layer of your fingernails-trust the voice of

experience!). An apron is a very good idea. Always dye outside, or in a well-ventilated area, as thechemical vat in particular causes harmful vapours when heated (the fermentation vat just smells really

bad). Remember,you can wear a vapour mask. You cant put one on your cat. Trust me.

Interesting Fact:Indican is a by-product of the indigo plants metabolic process meant to resist insect

attack, which gives indigo-dyed fabric a mild insect-repelling quality!

Bibliography:

Burnston, Sharon Ann. Mood Indigo, the Old Sig Vat or Experiments in Blue-Dyeing the 18th

Century Way 2005. May 4, 2005. .

Crowfoot, Elisabeth, Frances Pritchard and Kay Stanisland. Textiles and Clothing 1150-1450. The

Boydell Press. Woodbridge. 2001.

Emmett, Susie. New life in an old dyeNew Agriculturalist Online Issue 14: 00-2. Jan 20, 2007..

Gibson, Arthur C. WOAD IS ME Date Unknown. Plants and Civilization. Apr 28, 2005.

http://www.botgard.ucla.edu/html/botanytextbooks/economicbotany/Isatis/

Mattson, Anne. Indigo in the Early Modern World. Date unknown. Jan 20, 2007.

< http://bell.lib.umn.edu/Products/Indigo.html>


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Polo, Marco. The Travels: Description of the World. Trans. William Marsden, Thomas Wright.

Konemann. Koln. 1996.

Priest-Dorman, Carolyn. Colors, Dyestuffs, and Mordants of the Viking Age: An Introduction Apr.

24, 1999. May 4, 2005. .

Indigo: A World of Blue Maiwa Handprints Ltd. Video Documentary. Date Unknown

Maiwa Handprints Ltd. Indigo: Natural or Synthetic 2005. Maiwa Handprints Ltd. Feb 22, 2007.

West, Jean M. The Devil's Blue Dye: Indigo and Slavery. Date Unknown. Slavery in America. Feb

22, 2007. < http://www.slaveryinamerica.org/history/hs_es_indigo.htm>

Wisniewski, Mark. Dyeing to Dance. Hiroba International, Japan. 2004.

Liles, J.N. The Art and Craft of Natural Dyeing: Traditional Recipes for Modern Use. University ofTennessee Press. 1990.

http://invention.smithsonian.org/centerpieces/whole_cloth/u3tc/u3materials/natDye.html

Kew Gardens. Indigo date unknown. Plant Cultures: Exploring Plants and People. Feb 22, 2007.

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