Oklahoma is derived from the Choctaw Indian words "okla" meaning people and "humma" meaning red. Oklahoma is my home. Tinctoria is Latin, meaning to dye or color things; this is my work.

17 March 2010

Notes on Dyeing the Blues

Sky and Moon, Oklahoma, 2009.

Dyeing with Indigo is an art, a science, a skill and it is magical.
Blue is rare in the natural world except for our expansive sky and reflective water. There are not even very many blue flowers. Indigo is the only natural blue dye. Indigo plants inhabit every continent, making it one of the oldest natural colorants in continual use. Because of its extensive geographic accessibility, many cultures have developed their own practices for growing and extracting these valuable and desirable blues. 

Close up of Indigo Dyed & Over-dyed Yarns.
Heather Clark Hilliard, City Arts Center.
'Dyeing the Blues' Workshop, 2010.

The process of extracting and dyeing with indigo is mysterious and complex. In fact, the plant leaves from which the blue color is extracted do not show any indication of “holding” the valuable blue dye called indigotin. Indigo has been in use since at least 2000 B.C. but it was not until the late 1700’s that indigo’s chemistry was beginning to be unraveled. Although we are able to explain the chemistry of indigo in modern scientific terms, it still possess elusive behavior and captures our imaginations.

Fresh Polygonum Leaves, 2009.
'Dyeing from the Garden' Workshop w/ Liesel Orend.

Indigo is a vat dye, meaning that it is only soluble in an alkaline liquid and the dye is fixed on the fiber by oxidation. Therefore, indigo also does not require a mordant. There is a colorless substance in indigo bearing plants which is called glucoside or indican. The indican is released from the plant material when the leaves are crushed and covered with water. Once bacterial enzymes develop, they consume the indican/glucoside, leaving behind indoxyl or indigotin. Indigo is a very light-fast and wash-fast natural dye source.

Indigotin is the insoluble form of indigo. This is the form of indigo that is marketed and sold. Indigo vats can be made from fresh leaves if one grows their own indigo plants. Rita Buchanan’s book A Dyer’s Garden: From Plant to Pot, Growing Dyes for Natural Fibers gives instructions for growing and dyeing with the fresh leaves of Indigofera suffruticosa (p.104), Polygonum tinctorium (p.106), and Isatis tinctoria (p.108).

Fresh Leaf Indigo Bath, 2009.
'Dyeing from the Garden' Workshop w/ Liesel Orend.

The quality of the indigo growing and production determines the quality of the dye. Some indigo may contain a high percentage of impurities, diminishing the valuable blue dye.

Making indigo soluble in water requires alkalinity and the reduction of oxygen. This can be a chemical process or it can be a natural process. Indigo White refers to the stage in the dyeing process when the insoluble indigo has been made soluble. When the indigo bath turns the decidedly beautiful green/yellow color, the indication that the vat has been properly reduced of oxygen, and the alkalinity and temperature are appropriate for the kind of fiber being dyed, then the dyer may proceed, gently submerging their cloth, dyeing to the desired depths of blue. 

Indigo Dyed & Over-Dyed Skeinlettes
Heather Clark Hilliard, City Arts Center. 
'Dyeing the Blues' Workshop, 2010.

There are many plant species containing indican that vary in geographic locations and growing conditions. The indican-bearing plant species range from small trees to shrubs to biennials or annuals. They are represented by several plant families: Leguminosae, Cruciferae, Apocynaceae, Polygonaceae, Acanthaceae-Acanthoideae, Papilionoideae, Asclepiadaceae, and American Eupatorieae. The following plant species are the most common for indigo dyeing and most of them are currently cultivated. 

Polygonum tinctorium (dyer's knotweed) is in the buckwheat family and is cultivated in Japan.
Indigofera tinctoria or tinctorium is a legume and grown mostly in India.
Indigofera suffruticosa is grown mostly in the Americas.
Indigofera guatemalensis is grown in Guatemala and possibly other Central American countries.
Isatis tinctoria (woad) is a biennial  and grown in Europe, especially France.
Lonchocarpus cyanescens or Philenoptera cyanescens is used in West Africa.
Nerium tinctorium or Wrightia tinctoria is an oleander and used in India and Southeast Asia.
In recent years there has been a resurgence in the cultivation and use of indigo. Growing Indigofera genus is good for the soil; many of the cultivated indigo plants are legumes which add nitrogen back to the soil instead of depleting it. The subtle colors of natural indigo cannot be duplicated by synthetic indigo, therefore there is a desire among artisans to continue to use natural indigo. There is an art, science and skill to growing indigo plants which is not only imperative but also beneficial to preserve. The article “Ai-shi, Japan’s Indigo Masters” by Rowland Ricketts, III in Shuttle Spindle & Dyepot Winter 2000/01, p.25-29 discusses in detail the Japanese methods of growing and producing indigo from Polygonum tinctorium. 

Indigo Shibori with Painting, sample on cotton.
Earth Pigments Workshop w/ John Marshall, 2009.

Dorothy Miller introduced Polygonum tinctorium into the US. The excellent book Indigo From Seed to Dye remains a valued resource about indigo history, cultivation and artisan dyeing methods.

There are many recipes for dyeing with indigo. The following  article in HAND/EYE, “Get blue at home: do it yourself indigo” is about Earthues' process for making an Indigo Stock Solution and preparing an Indigo Vat:

Additional Bibliographic and Information Resources about Indigo:

The article “Close Call”, published in 'Turkey Red Journal', by John Marshall, is about saving the production of Indigo in Japan:

INDIGO, Jenny Balfour-Paul, Archetype Books, 2007. 

Visual article about Jenny Balfour-Paul from Inspired Magazine:

SPINDIGO: the sustainable production of plant derived indigo

Woad Production and Products:

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