It is exciting to see such a passion for indigo these days, and especially the active exploration that is happening. With this also comes with a deeper understanding of indigo dyeing and process.
Vats reduced with chemicals such as sodium hydrosulfite or thiourea dioxide used to be the norm when I first learned indigo dyeing in the 1970’s. But now, many dyers have abandoned those chemical reduction vats and are returning to more benign processes. They are now making quick-reduction vats that are reduced with sugar, fruit, plants, or iron – thanks to the teaching of Michel Garcia. Some are growing their own indigo to explore fresh leaf dyeing and pigment extraction. Others are making sukumo – a long process of composting persicaria tinctoria leaves – Thank you Debbie Ketchum Jirik for offering an online class this past fall. Recently, Stoney Creek Colors has introduced a natural, pre-reduced indigo. And more dyers than ever are now exploring vats that are reduced by fermentation.
Fermentation is the process that has captured my interest in recent years. The long-term committment seems to fit my own “stay at home” life right now. The lower pH is suitable for all fibers. Most of all, it’s been an interesting adventure. Something that once felt out-of-reach has now become my preferred process.
The fermentation vat utilizes plant material to initiate and maintain an alkaline fermenting process, which causes the indigo to become soluble. During fermentation, plant material is broken down, creating bacteria. Lactic acid is produced, making it necessary to monitor the pH on a regular basis.
Madder root is a common plant material used in a fermentation vat. There is a long history of its use in indigo vats. It is usually combined with wheat bran, which ferments readily. There are many recipes in old manuals for this Madder Vat.
From The Dyer’s Companion by Elijah Bemis (originally published in 1815, Dover Edition, 1973)
for a vat of 12 barrels (not sure what a “barrel” is)
- 8 lbs potash
- 5 lbs madder
- 4 quarts wheat bran
- 5 lbs indigo
When I first leaned of these vats made with madder, I struggled with the idea of using perfectly good madder root to reduce an indigo vat. But I have now come to understand that these vats were most likely made with “spent” or “used” madder. I remember Michel Garcia talking about how the “used” madder from professional dye studios in the past was sold to the indigo dyers after it had been used to produce red dye. Indigo dyers have no need for madder’s red colorants and thus nothing was wasted.
So, I am dismayed each time I hear from someone who has made a fermented indigo vat using “new madder root”. “Spent” or “used” madder is every bit as effective as a fermentation booster as fresh or “unused” madder.
Most of the madder I use in the studio is in the form of finely ground roots, though chopped roots would work as well. When my madder dyebath is finished, I strain the ground roots and dry them for later use in an indigo vat. It’s that simple! And nothing is wasted.
Plant materials, other than madder, can be used in the fermentation vats. I frequently use dried indigofera leaves, as well as woad balls and have even begun a “hybrid “ vat using sukumo with indigo pigment. My most recent experiments have used both Dock root and Rhubarb root successfully. Madder, Dock and Rhubarb are all roots, all anthraquinones…..
Natural Dye: Experiments and Results 
Thanks for this interesting post! Off topic – to your knowledge, has anyone used natural dyes for snow/ice dyeing, please? Thanks.
Sorry, but I do not have any experience with ice dyeing.
Happy New Year! Thank you for sharing that spent madder bath can be “upcycled” as the redux in the indigo vat. I hadn’t considered it. I tried a madder reduced indigo vat a while back (and yes, with fresh dye stuff) but didn’t get it right. However, wondering if after so many months of it sitting I might try to revive it! On another note, I switched to Michel Garcia’s 1-2-3 vat 4 years ago and never discard fruit, etc., that can be used in the fructose vat. An economical and zero waste approach!
I love following your fermentation vat progress Catherine. Thank you for sharing so generously as always! Looking forward to the day I can commit to setting up big fermentation vats when my kids are slightly more independent- I have so much saved spent madder root! Im inspired now to make a few smaller test vats as you’ve done. Im curious about other potential local waste streams I can tap in my area- I’ve had my eye on olive trees lately with big curiosity!
I wonder how many other spent dye plant materials can be used to ferment an indigo dye vat. What are the constituents of madder that make it work so well as a indigo vat fermenter. Henna is another indigo vat fermenter.
it’s been my experience that henna requires a higher pH. But the madder, dock root and rhubarb root are all anthraquinone dyes, which should be a good starting point for exploration.
Thank you for you. I appreciate all that you so willingly share. Happy New Year.
Sharon
Super interesting – thanks. Especially in the context of my study on purple…..would love to talk!
Elena
Hi Catherine,
Thanks for this. I love tending my fermentation vat. It’s like having a pet. it needs to be fed and can sometimes be smelly. Last summer’s vat was made with soda ash, dried indigo leaf from Stony Creek, wheat bran and powdered indigo. It was my best vat ever. I think the question of whether you use spent dye stuff or fresh is also related to overdying mordanted fiber with indigo. With my indigo leaf vat I experimented with:
1. Indigo dyeing of unmordanted fiber which were then mordanted and dyed in weld and;
2. An indigo overdye of weld dyed and mordanted fibers.
I dyed white wool, grey wool, bleached cotton, natural linen and natural hemp. There was just the slightest difference between the two dyeing methods. With fresh madder vs. spent madder, the results may be more apparent. Just in case you are looking for another experiment!
Love your blog. Thank you, too, for your workshop on woven shibori. It launched me on a most amazing journey into natural dyes.
Annette
Hi Annette! Glad to hear that you are still dyeing and enjoying the process. Stoney Creek has continued their grand success!
Thank you so much, Catharine!! Your posts are always so interesting and helpful!
fascinating and so informative – thank you. I really want to explore these methods this year.
Can you comment on the pH level and temperature of your fermentation vat? At what point do you decide to feed it? Recently I have noticed a chalky blue layer on my fermentation vat. I have been stirring it back into the vat. Do you have any idea what this might be?
Happy New Year Catharine!
I’m also enjoying my Fermentation Vat during this home bound time.
I’m using fresh & dried Indigofera that I grow (& from the wild)and cassia found in the wild for reducing,(after searching for a local abundant plant & lots of Trial & Error!)
To create my own Blue stew.
Thank you for sharing and for all of your experimental dye inspiration!
Leigh
It’s my understanding that madder has antioxidant properties which is a characteristic that makes it useful as a reduction agent in an indigo vat. I’ve notice that my madder dyebaths seldom go mouldy and assumed that this is because of these same properties. Thank you for sharing your experiments and this comparative analysis!
Despite, its name, an antioxidant is not really a reduction agent. It prevents oxidation but does not actively reduce anything. These are the subtleties of the science that we dyers struggle to understand.
You mention dock as a source for a fermentation vat. There are many types of native docks here in the midwest. Which types or genuses are usually used?
I used common curly dock (rumex crispus). It was dried and ground.
Catherine, you wrote this: “ for a vat of 12 barrels (not sure what a “barrel” is)”. In my research a year plus ago, I discovered that a barrel was 50 gallons. I found it in an old book, possibly at archive.org or through researching whiskey barrels of 1815. 😇
Anyway, based on that, I determined that for a 5 gallon vat the following:
1 ounce potash
5/8 ounce (.64 oz) madder
1 fl. ounce wheat bran
5/8 ounce (.64 ounce) indigo
I got there by calculating 1 barrel as 8% of 12, 5 gallons as 10% of 1 barrel. The rest of the calculations followed by converting pounds to ounces and determining the amounts at 8% and 10%.
Now, I’m gonna wait until the agro shops open to call around and see if they have potash. Heaven knows they don’t have soda ash any more. I’m in the Caribbean.
It’s always interesting to try and translate old recipes and quantities. The proportions seem right on this, but, I usually use slightly large quantities of indigo and everything else per liter of volume.
Some more research turned up that boiled water buffalo belly skin yields collagen. So, the option is either animal based or plant based collagen. The latter is Irish moss, which is used in doing fabric painting. Interestingly, the collagen is applied after the indigo dyeing, and the fabric is dried and dyed again. IIRR, it binds the dye to the fabric and so would prevent crocking. Worth a shot.
You are digging deep into all the possibilities! It’s like a treasure hunt.
That’s how I see it. I love to read the old books, see what they did, how, read their solutions to problems. It’s exciting.
Hi Catharine
Thank you for this interesting post! I’m experimenting with this recipe and I want to clarify: When you say lime is it then the lime juice from a fruit or Calcium hydroxide?
Kind regards
Amalie
Calcium hydroxide
That’s what I thought. Do you think I could use ammoniumhydroxid or soda instead?
When making a slow fermentation vat, soda ash does provide the necessary alkaline for a pH of 8.5-9.5. The pH needs to be maintained. Sometimes adding small amounts of calcium hydroxide will help with that.
Alright. Thank you for your reply!