New ways to do indigo

17 September 2014

On Friday 4 of us gathered together to dye indigo.  They had things they wanted to dye, I wanted to explore two new ways of making indigo vats.

I learned to dye indigo, and many other dyes, from Michele Wipplinger.  She taught me how to make a chemical vat using lye for the mother stock and thiourea dioxide for the reducing agent.  This has been a reliable vat for me and I have used as my default indigo vat.

One summer in the early 1990’s I kept a fermentation vat.  The biggest problem I had was keeping it warm enough. It did not like to cool off over night, I resorted to electrical heating pads/blankets but it was obvious to me that I did not have the right set up.  There is some reason that many on going indigo fermentation vats  are set in the ground and or have provisions for gentle heating.

Anyhow, there are now directions for new types of vats: one using pre-reduced indigo and another organic vat advocated by Michel Garcia, a biochemist, avid natural dyer and author (see references at bottom).  Both of these by-pass the use of lye, sodium hydroxide, which is getting harder and harder to buy in small amounts, and is quite hazardous to handle. Also I had heard several people advocate the use of hydrogen peroxide to reduce the crocking of indigo, and consant problem.

I had previously tried Garcia’s 1,2,3 Vat without success.  So I reread the directions and got some new supplies in: distilled water (for non-chlorinated water) and pickling lime and cal— both food grade lime, before I had tried tap water and gardening lime.

For the pre-reduced indigo I purchased from Pro-Chem and followed their instructions.

And just for security, I made sure that my mother stock for a traditional chemical vat was reduced and ready to go. Just as a back up.

Here is a look at the supplies for all 3 vats:

indigo supplies

Here is a list of supplies I had on hand:

  • Indigo
    • synthetic, micro-perle
    • pre-reduced indigo
    • natural indigo, several sources
  • Alkalis
    • lye
    • soda ash, sodium carbonate
    • ammonia
    • pickling lime, cal-both food grade lime
  • Scours, detergents
    • synthrapol
    • eco-scour from Earthues, for cellulose
    • Orvus paste
  • Reducing agents
    • thiourea dioxide
    • fructose
  • Protection for protein fibers
    • hide glue
    • gelatine, unflavored
  • Neutralize
    • vinegar for proteins
    • tea, tannic acid, for cellulose
  • Aid for oxidizing
    • hydrogen peroxide, 3%  this helps reduce crocking

Also had on hand pH strips for measuring high pH’s, 9-11 and distilled water.


We followed the instructions for the mini-vat for wool  but made it in a plastic bucket and keep it warm in a water bath. I added 25g of pre-reduced indigo and hide glue.    The slowest step is dissolving the soda ash.  It turned green shortly and we dyed wool, alpaca, leather and silk in it.  One dip gave a medium blue, two dips a medium dark blue.  It held up well as we dyed shibori pieces.  We stopped when the vat was down a third and poured the oxidized drippings back in the vat.



Since I had had trouble with this  all four of us made a half gallon mason jar for the vat, using a variety of indigos (not the pre-reduced ones) and limes with the hope that one combination would work.  We each added 25g of indigo to the vat and used distilled water.  Each person was to keep track of what they used.  I went first and put mine aside .  I could see that it was starting because of the flecks of coppery scum on the surface but in an hour the clear  settled liquid was neither green or brown.  The others started to make theirs.  Sandy sprinkled lime all over, turned hers in a globby paste before adding the full amount of water.  She sat it down and in 15-20 it turned brown with a bit of flower on top!  So we added it to a vat and started dyeing.   The goods came out a very pale blue.

It took 4-5 dips to get the same value of blue that we got with the pre-reduced indigo pot. we used the same dipping process for both.

Into the vat for 3-5 min., out and into a bath containing hydrogen peroxide for 15 min. then air exposure for 30 min. more. Repeat until darker than the desired color.  After a long final oxidation, neutralize by soaking in vinegar water for 20 min. and finish with a vigorous wash with synthrapol.


My mason jar of 1,2,3 vat turned brown also so I added it to the vat.  The vat now had a total of 55g of indigo but still only gives pale colors.  You can build up layers.

The 1,2,3 vat has remained an active vat, staying reduced for 4 days with no effort on my part.  I suspect that this is due to the sludge in the bottom.  Calcium hydroxide is not very soluble and it probably is some of what are the solids on the bottom where it acts as a reservoir and keeps the pH constant.  I wonder if there is undissolved fructose there too that keeps it reduced. I have been putting a few things in each day and the vat holds well.

Today I have been reading more about the 1,2,3 vat and others have commented on the pale colors. I did see that someone suggested that the goods needed much longer in the vat, 30 min. was suggested.   I will try that tomorrow.

The pre-reduced indigo vat has been reluctant to reduce after the dripping were put back, I have made 5-6 small additions of reducing agent and it is just swamp green so it still needs a bit more.


Both these new vats worked! We did not need to use the lye for either vat.  This is progress for home dyers.  I will continue working with both these vats.  The pre-reduced indigo was quick and easy and gave a nice depth of shade. Great for a workshop.  The 1,2,3 vat holds very well over several days, nice for a long project that requires many dips.

The hydrogen peroxide bath turned the dyed goods  blue almost instantly.  It may reduce the crocking ( I have not yet got to testing this yet) but it takes away the fun of seeing the color change before your eyes.



2 Responses to “New ways to do indigo”

  1. Sandy Says:

    I did not see anything wrong with my work area. Looked just like my kitchen when I cook. And, I did clean it up. You called my jar of ingredients paste but believe me it was more like concrete. I thought I had messed up big time. Who would have thought it would actually turn out to be ok.


  2. coolquilting Says:

    I have used the pre-reduced indigo kit and it worked great!


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