Woad -

Woad
Isatis tinctoria

The woad plant has a fresh wildflower appearance that brightens any garden. It has become known as the origin of the blue dye used in ancient Celtic body art and coloring textiles. However, woad has a long complex history.

Botanical Information and Plant Properties

The plant is native to Europe and Asia. Its botanical name is Isatis tinctoria and belongs to a genus of close to 30 species. It is either biennial or perennial and grows in branches of small leaves and yellow flowers in the summertime with black seeds resembling pods.

Woad's medicinal uses have been known as far back as the late 1500s in traditional Chinese medicine. It is an astringent plant known for reducing fever and inflammation and is reported to have antiviral properties. The parts of the plant used in natural medicine are the leaves, roots, and pigment.

Woad Plant and Dye in History

Films such as Braveheart starring Mel Gibson popularized the concept of woad being used in Celtic body art. Julius Caesar, in the Conquest of Gaul, used the Latin word vitro in reference to the paint the Celts and Picts used which past scholars believed to mean woad. However, this translation is debated and possibly means a blue-colored glass. Other suggested origins of this blue color mentioned by Caesar for the body paint are iron and copper pigments, the latter however being very toxic.

Woad was long used as a dye plant for its blue color in textiles. It became a subject in the Indigo Wars when the plant indigo began to be imported from the tropics. Woad growers fought to retain their status as leaders of the production of blue dye pigment. Indigo won the war however replacing woad because the process of producing dye was less expensive from indigo than from woad.


Growing and Harvesting Woad


Woad grows best in zones 3 through 8. It's best not to grow it in the same ground for more than a couple of years. It thrives in well-drained soil and can be planted by seed in the spring or autumn.

Caution: Woad aggressively self-seeds and can become a pest problem.


Woad is very easy to grow in sunny or partly sunny locations. As a biennial it grows one year, flowers and produces seed the second year and dies.

All above ground parts of the plant will produce indigotin, but in fairly small concentrations so be willing to plant as much as you have room for. The dye can be processed any time with any amount of plant material, but being a biennial, flowers are only produced the second year, but in tremendous abundance. To prevent woad from becoming a serious weed problem cut back all but one or two flower stalks and the remaining flowers will provide all the seeds you need for the next season.


Home growers still use woad leaves to extract pigment for dying fabrics and for medicinal purposes. If planted in the spring, harvest the leaves between July and September. If planted in the autumn, harvest them between June and August.

Regardless of its history, woad is still being used for blue dye and to add a splash of yellow to a dull corner in the garden.

A bit of vocabulary first: "indigotin" is the blue dye, whether you get it from woad- Isatis tinctoria, true indigo- Indigofera tinctoria, or some other source. To process fresh woad into blue dye, you will need fresh woad plants, sparkling non-sudsy ammonia, an egg-beater, cooking whip, or electric mixer; some glass jars and a non-stick cooking pan. Be prepared for a small yield because woad contains only one tenth of the indigo that true indigo plants contain. I have had trouble growing indigo, but here in Michigan I can grow all the woad I want. Woad spreads so aggressively that some states have laws prohibiting it, check first.

Once you have grown woad and have leaves to harvest you can move onto the following process.

1. Cut woad plants, including leaves, stems and all above ground parts of the plants and chop into small parts. Do not finely shred or put the leaves through a food processor because it will be difficult to separate the vegetable matter from the dye later on.

2. Pack chopped leaves into a glass jar until full and carefully add boiling water to avoid breaking the jar. Put on lid, and let steep for 1 hour.

 3. After an hour the water will have turned a dark red-brown. Pour the woad tea out though a colander with a linen cloth. Be careful to strain all herb matter out now while the dye is dissolved and the liquid is easy to separate.

Next, first make the solution alkaline by adding ammonia and then the liquid must be oxidized by beating air into it. Be sure to use non-sudsy, sparkling ammonia, as the regular sudsy type will produce large amounts of unwanted foam when air is worked into it. An eggbeater can be employed effectively, but an electric mixer is my choice. Put the woad liquid into a mixing bowl and add enough ammonia to give a pH reading of 9 or more on litmus paper. Most litmus paper will not read as high as that, but adding extra ammonia will not hurt. Turn on mixer to "whip" or medium to high speeds, making sure that the beaters are not completely immersed in the liquid: the goal is not to mix the solution, but to get air and oxygen into it. Keep working the solution for 10-15 minutes and watch as it darkens and some blue particles begin to appear on the top.

The now oxidized liquid has indigo-blue in it ready to settle out and purify. Put the liquid into tall, narrow jars and watch the darker indigo settle out over an hour or more. When there is obvious sediment on the bottom, carefully pour off the clearer solution while keeping the dark sediment intact. Add water to the sediment and let the indigo settle out again. Repeat these steps until you have a clear liquid with blue sediment on the bottom. You now have fairly pure indigo and water and are ready to evaporate the water off and powder up the indigo for storage. Pour off the water and pour the remaining water and indigo into a Silverstone or Teflon pan and let the water evaporate. When I tried other surfaces to dry out the indigo, the indigo stuck to it and had to be chipped off so I turned to more high-tech non-stick surfaces with great success. Indigo dried on Silverstone tends to peel up from the pan and can be easily removed, powdered and stored in a jar for further use.


Note- From this point on the dye will be referred to as indigotin since woad and indigo produce the same chemical just in different amounts, and indigo-based indigotin is virtually indistinguishable from the woad-based product. -R. The blue dye chemical indigotin, from indigo or woad, is the only natural "vat" dye in widespread use and though it is complicated to dye with, indigotin yields long-lasting and beautiful colors. Vat dyeing involves changing the normal indigotin, or indigo blue, which is not water soluble and will not bond to fibers, into another form called indigo white which will easily dye about anything. The indigo white is then returned to its blue form, and the now blue dye is locked into the fiber and is resistant to being washed out, which makes it a very powerful and long-lasting dye.

In practice, the fibers are dipped into a specially prepared dyebath of indigo white and when removed from the bath the dye reacts with the oxygen in the air and rapidly becomes indigo blue. The more often the fibers are dipped the deeper the blue color. Thus, the only truly complicated part of the process is preparing the dyebath.

To prepare the dyebath a "reduction" reaction to remove oxygen from the solution is required along with a change in the pH required to dissolve the dye. The reduction reaction was historically done by bacterial action in a vat of indigotin, aged urine, wheat bran and other additives that was a long and very strong smelling process. This was the traditional indigo vat or blue-pot. The fermented urine produced ammonia that shifted the pH level of the vat into the alkaline levels required for the effective use of the dye. More modern techniques involve chemicals such as sodium hydrosulfite or commercial preparations like Rit brand Color Remover and ammonia or some other alkaline agent.

[From:  http://my.net-link.net/2E/EB/rowan/Woad%20Page/woadpage.html ]

Woad (Isatis tinctoria) is a native of the Mediterranean and belongs to the family Cruciferae (the brassicas), as do broccoli, cabbage and rape seed.




The neon yellow flowers, which appear in May, have a wonderful fragrance and attract plenty of bees.



The black seeds are winged, resembling small tongues, and can produce an olive dye.

Woad is a biennial plant. That is it grows for two years before dying down.

In the first year, it forms a low-growing cluster of leaves like spinach.

The leaves are harvested for dye production at this stage, and in the first year only, because they have little or no colour when they reach the second year.

In the second year, the plant produces tall stems up to five or six feet in height that are surmounted by sprays of small, neon yellow flowers.




The leaves become longer and thinner and the plant looks quite different.



After producing seeds, the plant dies down.
 
 
 
 
 
 
 

When the harvest is finished, leave a couple of strong plants for seed production. It is best to dig up the other plants before they become too large and, therefore, difficult to dig up.




Collect all the seeds as soon as they are ripe. The seed stalks can also be used in flower arranging.



Be careful not to let woad self-seed, as it can be an invasive plant . It does not however spread vegetatively.
 
 
Woad as an anti-cancer agent


It is not only a blue dye that can be extracted from woad; the woad plant has also become a weapon in the fight against breast cancer. Recent research has found that this plant has 20 times more of the anti-cancer chemical glucobrassicin than broccoli. It is difficult to extract the chemical from broccoli, so woad provides an effective alternative. Woad can produce even more of this chemical if the young leaves are damaged. Do not try to eat woad though as this plant is not edible.