The frosts are coming so it was time to cut back all of my Woad and Japanese Indigo plants. I harvested about 800 grams of fresh leaves from about 10 woad plants and about 250 grams of fresh leaves from the Japanese Indigo plants.
There are many different instructions on how to make a Woad or Japanese Indigo vat using fresh leaves. I read through several and thought I would try my own approach. I followed a similar procedure for both the Woad and Japanese Indigo vats.
The directions I’ve read warn that Woad (or Japanese Indigo) is sensitive to hot water >90 Deg C yet the woad needs to be heated up to help release the indigo pigment.
I used hot tap water rather than heating this on the stove, so I could control the amount of heat. Since my tap water wasn’t quite hot enough, I added a kettle full of heated water to the water to raise the temp to about 80 deg. C. I cut the woad leaves into small pieces and let them soak in the hot water for about an hour.
Apparently 115 deg F (or 46 deg C) supposed to be the optimum temperature for the release of Indigo pigment from the plants.
When the temperature decreased to <50 deg C I scooped the cut leaves into an organza mesh bag. I thought that this would help prevent the messy leaf sediment in the bottom of the indigo vat. Then I transferred the Woad dye water into a large plastic bucket.
I thought I would try to use a fructose fermentation method, following Michael Garcia's 1,2,3 guidelines, as I've had good success with my previous Fructose Indigo vat.
I have no idea how much indigo pigment is really in the leaves, so I added 20 grams of Calcium Hydroxide to the indigo vat and 40 grams of Fructose. The pH rose to 10.4.
I put the organza mesh bag filled with the Woad leaves back into the bucket and put the lid onto the vat. I did the same with the Japanese Indigo vat.
I checked both of the vats about an hour later and was pleased to see some blue bubbles and the organza bags turning blue.
Now I wait patiently.. perhaps tomorrow I can dye some beautiful indigo grown in my own garden.
There are many ways to prepare an indigo vat, some use soda ash and spectralite, some use some use sulphuric acid, some use iron and some urine. For this indigo vat, I am using a fructose base. You can also use ageing fruit instead of fructose sugar.
The fructose indigo vat was developed by Michel Garcia. The addition of the fructose sugar acts as a reducing agent to the Indigo. The sugar removes one of the oxygen molecules from the indigo making it soluble in water.
The addition of the Calcium Hydroxide (slaked or hydrated lime) changes the pH from an acid to a base. The proper pH to get good colour on wool should be about +9 and for cotton and cellulose +10.
When the yarn or fabric is dipped into the indigo dye vat, it turns a green colour. When the yarn is raised into the air, the oxygen molecules from the air, bind with the indigo and turn the green into blue. To get darker and more intense blues, the yarn needs to be dipped into the indigo vat and raised into the air to oxidize several times. The colour builds up onto the yarn or cloth in layers. Keep dipping and airing out the yarn until the desired level of colour is achieved.
An Indigo vat can be re-used and kept alive for several weeks until all of the indigo has been exhausted.
If the Vat still has indigo but has turned blue, reheat the Vat to 50 deg C. Check the pH. Add about a teaspoon of fructose crystals and wait 15-30 minutes.
The Vat should turn green. If it is still blue add some Calcium Hydroxide. pH should be +9 for wool, or +10 for cellulose.
The Fructose Indigo Vat uses a 1-2-3 ratio of substances.
1 part Indigo
2 parts Calcium Hydroxide
3 parts Fructose
I purchased some Tamil Nadu Indigo from Wild Colours.
I decided to make a starter indigo vat using 25 grams of Indigo. In theory, 25 grams of Indigo will dye about 1 kg of fibre. This will vary depending on the strength and depth of colour that you produce, and the Vat can be kept alive by checking pH and adding more Calcium Hydroxide or Fructose as needed.
I put about 200 ml of hot water into a large Kilner jar and added the Indigo powder. I stirred this until the indigo was dissolved.
I then added more warm water to fill the jar almost to the top.
I measured out 50 grams of Calcium Hydroxide
and 75 grams of Fructose.
I added the Fructose into the Indigo mixture and stirred until it was dissolved.
Then I slowly added about half of the Calcium Hydroxide, trying not to introduce air bubbles into the mix.
The Indigo starter needs to be kept warm while it reacts, so I placed the Kilner jar into a slow cooker filled with warm water. I left it on a low setting and gently stirred the jar about every 20-30 minutes.
After about 3 hours, a bronze film had developed on top of the water, and the indigo bath had turned green.
I let this starter vat sit overnight and kept it warm by wrapping a towel around it.
The following day the Indigo starter had separated into several lovely layers.
I put 10 litres of hot tap water (50 Deg Celcius) into a large plastic pail.
I carefully lowered and submerged the jar of Indigo starter into the pail. I gently tipped the jar to pour out the indigo taking care not to introduce extra air into the water.
I gave the Vat a gentle stir and let it sit beside the warm radiator. More patient waiting…
A few hours later: Indigo Fructose Vat: pH +11.2 Temp 30 deg C.
The Indigo Vat looked like it was ready to go.
A coppery finish had formed across the top and the dye water looked green.
I tested a few wool yarn samples and dipped them into the Vat. They came out green, but quickly turned to blue in the air.
Indigo Fructose Dye Vat Sample No. 1
For my first real test piece I dipped in a skein of handspun bleached flax. I dipped the skein into the Vat, pulling it out after about a minute and let it air for about a minute. I repeated the dipping 5 times and got quite a dark blue that I was happy with.
60 gram skein 160 m
approx. 260 m/100 gr
Indigo Fructose Vat Dye Sample No. 2
I tied a silk scarf with some marbles and elastics, creating a Shibori type of effect.
I dipped the scarf (dry) into the Vat, swirled it around and pulled it out to air for about a minute. I repeated the dipping 5 times.
First set of samples drying outside.
After you have finished dyeing your pieces, rinse them thoroughly in cold water until the water runs clear. Add a bit of vinegar to the final rinse, to neutralize the high pH of the yarn or fabric, as this can be damaging to your yarn if it is left.