As part of my foray into the natural world for research for my new novel, the other weekend I learned all about dyeing with colors derived from plants.
I attended the “Indigo Colloquium” at the UC Berkeley Botanical Garden.
Why indigo, I wondered as I signed up? What is it about that particular color that attracts such interest?
Turns out indigo is the color of denim. And since over a billion pairs of blue jeans are sold every year, how they are colored is important commercially and environmentally.
Coming at the subject from a level of complete ignorance, I learned that weekend that many plants throughout the world produce the color blue. Remember woad? If you were taught history in the dark ages as I was, you may remember that the Celtic warriors who opposed the troops of Julius Caesar when he invaded Britain terrified the soldiers because their faces were painted a fierce blue from the woad plant.
Woad (isatis tinctoria) is now considered an invasive weed in California. But it can be grown in home gardens to produce the blue dye.
Indigo, however, produces a stronger blue. Hundreds of different plants producing the color indigo are grown throughout the world, and the most popular for dyeing is persicaria tinctoria, otherwise known as polygonum tinctorium. The common term is Japanese indigo.
Indigo is a dye that adheres to the textile without the use of mordants. That’s a fixative produced by alum,iron, copper,or tannic acid often mixed with an acid like vinegar. For that reason, working with leaf-based indigo is safer for the home dyer.
I love the idea that over hundreds if not thousands of years, people have experimented with creating gorgeous color from plants that grown nearby. The process is a series of chemical reactions to release the color from the plant. For the home dyer, this involves heating the harvested leaves in a pot of distilled or rainwater to release the indican in the leaves, and adding a base such as baking soda, washing soda or ammonia to increase the pH to 8 or 9, which helps the hydrolysis of the indican to produce the molecule indoxyl. Then air is introduced to the mix, allowing the indoxyl to combine with oxygen to produce indigo. Finally, in order to make the color water soluble the mixture is reduced over heat with the addition of thiourea dioxide (helpfully available from the drug or craft store as Rit Color Remover). Add your previously wetted fabric to the dye for up to fifteen minutes, lift out carefully and hang to dry. The exposure to air makes the dye color fast and produces the final blue.
The color changes in the dye-in-process are fascinating. The flowers of the plant are actually pink. The composted or heated leaf brew is reddish-brown. Adding the alkali produces a yellow color, and agitating it to add air turns it to green. As the reduction process happens, and you add your fabric, your textile appears yellow green. Taking it out of the dye bath and hanging it up exposed to air turns it first turquoise, then indigo blue.
Indigo can also be produced synthetically. However, this is a petroleum based product (from benzene) and so toxic that synthetic indigo dye is no longer produced in this country. Most of the jeans sold in the world today are colored with synthetic dye made in China.
Some researchers have created a microbiology-based indigo by gene transfer from persicaria tinctoria into ecoli. It may be commercially viable in the future, but so far indigo manufactured through microbiology has not proven cost-effective.
But for now, there’s an opportunity for the revival of dyeing with natural sources of indigo to become a real alternative to synthetic dyes. If enough farmers can be persuaded to grow the indigo plants so that minimal dye batch sizes of consistent color are produced, then clothes manufacturers will be interested.
That’s the hope anyway.
In the meantime, I now know how to work the process of cloth dyeing into my story, in which there’s tension between old ways of doing things as rediscovered by a group of ageing hippies in Northern California, and the encroaching modern world. Can the old be made new again? As I learned, that is very possibly fact, not fiction.
By Jane Goodall, with Gail Hudson
Grand Central Publishing, 2013
This week I’ve abandoned my usual practice of reviewing a book by a non-famous author. That’s because the great Jane Goodall has, in her unique way, cut through journalistic “the sky is falling” tropes as well as academic gobbledygook to show us how plants can save our planet.
I’ve been reading a lot lately about trees and organic farming for my new novel-in-progress. So when I picked up Jane Goodall’s book, which is sub-titled Wisdom and Wonder from the World of Plants, it was in anticipation of learning about plants through her habit of keen observation. Ms. Goodall has, of course, achieved world-wide fame for her pioneering studies of chimpanzees in Gombe Stream National Park in Tanzania.
Seeds of Hope is far more broad-ranging than that. Written in a delightful conversational style, the book’s topics range from tales of early European plant hunters and a very brief history of our understanding of plants to the fate of the planet due to climate change and agri-business’s monocultures. It ends with a discussion of organic farming, and the remarkable ability of plants to adapt. As a conservationist, Jane Goodall sometimes lets her mission get in the way of facts, as for example, in the chapter on GMO foods. Her arguments on their dangers are anecdotal rather than scientific. However, she is making a broader point – that human hubris has led to a loss of plant diversity. Nonetheless, as she also points out, flora indigenous to one area have been hybridized for centuries to provide an even greater variety and range of their species.
Never polemical, but written in a tone that invites the reader to join in, as if we were sitting with Jane around her campfire, the book inspires a re-thinking of what we wear and how we eat.
The book starts with a description of The Birches, her grandmother’s home in southern England. Born in 1934, Jane was sent to live there with her sister and mother while her father served in World War II. It was an exceptionally happy home, with a grandmother who cooked from the garden, baked bread, and made her own jam. Lucky Jane! Her freedom to roam the garden, the woods beyond, the cliffs, and the beaches nearby inspired her love of nature.
What’s instructive about the authorial choice to include so much about this childhood in the book is that these happy memories occurred during a terrible war, in which food was rationed and suffering was rampant. Jane was a child, true, and not personally involved in the horrors of World War II. And yet within it she found her Seeds of Hope.
Jane Goodall is saying to us that even if the natural world has never seemed more threatened, we can do something about it. “If plants could be credited with reasoning powers, we would marvel at the imaginative ways they bribe or ensnare other creatures into carrying out their wishes,” she writes.
Humans are their greatest rival. But since we depend on plants for our survival, we can make sure they do. This book plants more than a seed of hope.