Curious Blue


Captured by Woad

I. A Woman of Woad

You seek alchemy. You crave the mysteries of an ancient blue. So you sign up for initiation, unaware that your seduction by woad has already begun. Why else would you, a writer, join for instruction with weavers of cotton, wool, and silk? Why else plunge your hands into smelly vats at a workshop on dyeing?

Woad is an old color. A conversation with history. A natural dye. An ugly plant. Locked in green leaves, compounds that break into pigments of blue. Blues that can be as bold as a Blue Jay feather or as tender as an azure sky at dawn, as dark as ink or as milky as glacial ice.

The workshop is in the morning, in your hometown, Seattle, in the outdoor amphitheater at Magnuson Park. You sparkle with the first warm sun of spring, with the prospect of what is to come. You and your fellow students–thirty or so, mostly women–assemble on tiers of stone seats. The cotton shirt you have brought to color is soaking in a bucket of cold water. Arrayed in a circle on the arena of grass are ten blue plastic garbage cans: the vats of dye.

The Master steps before the students and the workshop begins. Denise Siméon-Lambert is French. She is an expert on woad as a natural colorant. She owns a company near Toulouse, Bleu de Lectoure, where the plants are grown and harvested, processed to extract the pigment.

She is middle-aged and has short brown hair tipped with gold. Her narrow face is tanned and she wears silver hoop earrings and a pendant of a single clear crystal. A crinkled blue scarf wraps around her neck and her long-sleeved shirt is a spectrum of woad blues.

She speaks with her whole body, leaning forward, sideways, arms waving and pointing like punctuation. Her English bears the rounded vowels of Britain and is laced with only a light French accent. She fizzes with energy as she pushes to compress into this one moment the long story of woad: how the plant arrived in Europe some three millennia ago; how the pigment was the pulse of Renaissance wealth in Toulouse, still seen today in the 16th-century mansions built by woad merchants; how Napoleon sought this blue to dye the uniforms of his soldiers; how textiles made of woad-dyed thread are colorfast for centuries. Among the most famous, the Franco-Flemish Unicorn tapestries, a series of seven woven in the Middle Ages that hang today in New York’s Metropolitan Museum of Art.

Denise is a widow. She carries on the passion for woad discovered with her late husband, Henri. Their seduction began in 1994 when they bought an 18th-century tannery in Lectoure. The window shutters were a curious blue. Later they learned that woad paint repels insects. Together they mined the notes of Napoleon’s chemists, tested for five years, and delivered to our time the formulas for turning green leaves into natural blue dyes and paints.

As the Master talks, you notice that her hands are tinted blue. Then you spot a blue tattoo that snakes across the back of her right hand and wraps around her wrist bone. And all this confirms she is indeed a woman of woad.

Because you are a weaver of words, you have brought your notebook. But your hand cannot move fast enough to capture all she provides as precedent for dipping cloth into vats. You lay down your pen and you enter her dream.

II. Labeling Blues

Woad is a word of Anglo-Saxon root: wad. In French, woad is pastel, a cousin to the modern word for paste, pâte. In 17th-century France, pastel came to mean not only the plant, the pigment, and the dye, but also blue drawing sticks that were made by mixing scum from the top of woad dye vats with chalk, honey, and a bit of gum arabic. Today’s versions of these soft pastel sticks are for sale at Bleu de Lectoure, as are pastes of pure pigment, inks, water colors, sealing wax, and paints for plaster, fabric, concrete, wood, iron, even for the bodies of cars.

The plant’s Linnaean name is Isatis tinctoria. It belongs to the Cruciferae family and is related to cabbage and broccoli. It grows from Finland to the Azores, from the British Isles across Russia. In temperate climes, woad was–and still is–the best source of a natural blue. The leaves contain colorless compounds that can be coaxed with chemistry to give up blue pigment, part of the alchemy that leads to woad-blue thread and cloth.

The plant’s origins are in the Middle East and Asia. European textiles 2700 years old have been found dyed with this most durable and colorfast blue. In North America–in the western states of Washington, Wyoming, Oregon, Montana, and Utah–the plant is listed as noxious. So easily does the wind carry the seeds, so long the root, so invasive the plant that the propagation of woad is prohibited. Woad is a weed. Woad and weed have the same word root.

What describes a color? Shall we say woad produces blues that mimic the sky? May we specify the shades as the spread from the pale horizon at noon on a summer day to the overhead darkening as stars appear? Does it help to know that woad is not as purple as new blue jeans, nor as green as a swimming pool in the sunshine? Should we be surprised that synthetic dyes and computer screens cannot replicate the blues of woad? Shall we mention that the kings of France once controlled this color? What of the Roman stories of ancient Britons, the Picti, who are said to have painted their bodies blue with woad before battle? Why is the pigment from woad called indigo? Does it cast light to say that a different dye plant, grown only in the tropics, produces the indigos so familiar as denim? Is it useful to know that the word “indigo” means “from India” and comes from Latin, indicum, and from Greek, indikon?

III. A History of Differences

Woad and indigo are the same. Woad and indigo are different. This contradiction is key to an education in woad.

What is different: the plants and the climates they prefer. Isatis tinctoria, woad, grows in a range of temperate climates. The tropical indigos are found in Indigofera tinctoria, which thrives only in the hot latitudes.

What is the same: the compounds in the leaves that, when extracted and reacted, produce blue pigment. The names: indican, indirubin for reds, flavonoids for yellows.

Different: The ratios of compounds that determine the hues. More red (indirubin) means more purple, like denim; more yellow (flavonoid) fosters the sky blues of woad.

Same: The blues produced, no matter the plant, no matter the hue, are all named indigo. A confusing sameness.

More differences from history: For centuries woad was the local color of the British Isles and Europe: grown locally, locally produced and traded. Beginning in the Middle Ages and through much of the Renaissance, the coveted blue dye (for blues are rare in nature) was a local source of riches and power. But the low concentrations of indigo compounds in the leaves of woad yielded a dye that was good only for wool. The higher concentrations in the tropical indigos also worked on cotton and flax. For many years, the imported pigments were a luxury in Europe. Then shipping routes between the Asian and European continents matured, a vast trade opened, and prices fell. At the end of the 16th century, this set loose confrontations: The French and Germans, entrenched and invested in their empires of woad, fought the arrival of the preferred and now-affordable indigo that came mostly from India. Bans were raised against imports; deceits were disseminated about their low qualities. In Germany the foreigner was called the devil’s dye. Fortunes seesawed, but in the end, woad lost.

There was a brief revival in Napoleon’s era. It was 1806. French ports were blockaded by the British. Imported indigo used to dye the uniforms of soldiers ceased to reach France. Napoleon was desperate for a local blue. Massive plantings of woad ensued, research and experimentation. Notes were made by chemists, the notes rediscovered by the Lamberts. But when the blockade ended, indigo imports resumed. Dyeing with the European blue was too difficult, too complex. Woad slid away again. By the late 1800s synthetic dyes reigned and even foreign indigos faded out of favor.

IV. Alchemy From Green to Blue

Woad is a slow blue. Creating the pigment requires a patient and complicated alchemy. Alchemy: a word with ancient roots in Arabic (al-kimaya) and Greek (chymeia, a mingling, an infusion; chymos, juice, especially as extracted from plants). The alchemy of the Midde Ages, with its quest to change base metals into silver and gold, was a pseudo-science; it was also a protoscience that led to modern chemistry. And although the transformation of woad into a colorant for cloth is simply a series of chemical reactions, the word “alchemy” better captures the magic of extracting beautiful blues from the green leaves of plants.

In Europe and in the British Isles, when woad was the only affordable blue, processing began with the crushing and composting of leaves. The mixture was shaped into balls dried for storage and transport. Inside the balls, a tiny secret was at work: a bacterium, Clostridium isatidis, thriving in the interiors, using up the oxygen, beginning a transformation by fermentation that led to blue pigment.

Next, woad balls were crushed and wetted and spread on the ground. The growth of bacteria further encouraged, more fermentation fostered. The sludge, which heated up like compost, was turned and tended for as long as nine weeks to achieve the highest concentrations of pigment. According to an old account, the fermenting mass exhaled “a Urinary Volatile Salt” that filled neighborhoods with its rank ammonia smell. The dried-out residue–couched woad–was packed and sent to dyers for the next stage of alchemy.

This cumbersome and slow extraction by fermentation was improved by the chemists of Napoleon, though the goal was the same: conjuring blue pigment from green leaves. The research of Denise and Henri Lambert applied 21st-century knowledge and techniques to the Napoleonic work. Extraction was simplified so that no fermentation was required. One of the keys: the release of indican, the precursor of the pigment, depends on soaking fresh leaves in hot water that is precisely 113 degrees Fahrenheit.

Despite modern precision, the process remains a fragile alchemy. If the leaves are harvested too soon, if the water or the weather is too cold or too hot, if the dyemaker is distracted, then the instant of indican surrender will never arrive. If, however, the liquid is beaten at the magic minute of release so that oxygen is introduced, then a precipitate will form. Filtered, this becomes indigotin, pure woad pigment, the basis for paints and dyes. Four pounds of pigment require one ton of leaves.

The wizardry of dyeing cloth with woad requires reversing the chemistry of extraction. The captured blue pigment must be made to disappear, must dissolve into a alkaline liquid concoction that will deplete, reduce, the oxygen. When cloth is dipped into this potion and then exposed to air, the pigment will reappear entrapped in the fibers of cloth and will stay there for centuries.

V. Captured

The Master signals it is time to go to the vats. You wring out the water from your scoop-necked, white-cotton, long-sleeved shirt. The fibers have been opened by soaking, and are ready to accept the coming dye. You approach the vat that holds centuries of wisdom and practice. Denise and her apprentices have done the hard work of preparation; they have created and tended the dye to ensure the revelations of color that await you.

You look down at the liquid. It is olive-yellow and the surface is pocked by bubbles of blue scum. You notice the smell, a mild scent of barnyard. And you recall from the Master’s lessons that the Renaissance vats of Toulouse were nurtured with the urine of men. A convenient and abundant source of alkali, ammonia, needed to reduce the oxygen, dissolve the pigment. Today’s vats do not hold urine. You know that. There are more powerful, less pungent, friendlier modern chemicals–thiourea dioxide, sodium hydrosulfite–used by the Master.

With you at the vat is Maureen, an experienced dyer. You are both gray-haired elders. She counsels as you lower your cloth into the liquid. Gently, slowly, humbly (as Denise has advised), you watch the shirt shimmer ghostly yellow as it sinks below the surface. Oxygen is the enemy at this stage, so you must strive to prevent its introduction. You “burp” the neckline, allow bubbles of trapped air to escape. With a wooden dowel you tenderly prod the shirt to the bottom.

Maureen goes next. She eases in a long white silk scarf that billows from the breeze. You are the taller so you hold high two corners as she guides in the cloth. The dipping requires only a few moments, so it is already time to retrieve your shirt. You stir the bottom of the vat with the dowel and lever out the dripping mass of cloth. You extract your piece and then, because you know the vat is benign and because you want blue hands like the Master’s, you do not bother with gloves. With bare hands, you wring the cloth, hold it close to the surface so as not to introduce bubbles.

Your white shirt has emerged yellow but begins to turn green the instant it leaves the vat. The transformation has begun. Oxygen is the sorcerer, oxidation the reappearing act of the pigment. You shake the cloth, open the folds. Yellow turns to shards of green, emerging trapezoids of moving color. The pigment materializing.

You take your shirt to an empty spot on the grass and spread it on the ground. You smooth wrinkles from sleeves, neckline, body to fully expose it to air. You turn to answer a call for help from Maureen with another long scarf. When you come back your shirt has turned blue. Blue as if a chunk of the sky has tumbled to earth. Blue like blueberries smashed with cream, a blue cream you want to drink up, lap with your tongue, swallow.

You enter the cycle of dipping, retrieving, wringing, spreading open, returning again to the vat. The cycles of repeated transformation–yellow to green to blue. Layers of color that grow darker each dip. Satisfying. Unexpected. Controlled but not controllable. Denise has said if something goes wrong, it is you, not the vat.

Last dip, last wring, last step: rinse in clear water to remove excess dye. Then you hang the cloth on line that has been stretched between pillars around the top of the amphitheater. Your shirt joins strands of ribbon, loops of lace, a pillowcase, embroidered tablecloth, wool mittens, skeins of yarn, long scarves, t-shirts and canvas tennis shoes, tank tops, shopping bags, shawls, a ruffled blouse, a short-sleeved man’s shirt. The blooms of yellow and orange calendula at the edge of a community garden are backdrop for the lines of fluttering blue cloth. A bounty of blue that could humiliate the sky.

When you left the workshop that afternoon your fingers and nails were blue with woad. It was three weeks before the last bit of color faded from the moon above your cuticles. You wear your blue cream shirt often though the marks of a novitiate are clear: splotches of lighter blue, places that speak of the folds you left half-opened, of fibers hidden from oxygen. But you don’t care. The shirt has become talisman, as if it holds a charm, an incantation. You have been captured by the thaumaturgy of woad.

Nancy L. Penrose writes travel and personal essays. To read more of her work, please visit