Natural Dyes - Indigo, The Ferrous Vat

by - Thursday, September 05, 2013

The Maiwa Guide to Natural Dyes
What they are and how to use them

This This is the last vat recipe in our series "The Organic Vat." It follows our introduction, About the Organic Vat, our general procedure post, Indigo: The Fruit Vat, and our last post 3 Organic Vat Recipes.

The Ferrous Vat

This is called the “1, 2, 3” vat – it is a cold vat that is great for cotton and silk. It is not recommended for wool because of the iron.

The Ferrous Vat gives a beautiful dark indigo and has the advantage of being a cold vat that keeps for months. It is good for printing as it does not require long dips. It is a vat that has been known throughout history.

For a vat of about 15 to 20 litres
  •    20 g powdered indigo (1)
  •    40 g ferrous sulphate (2)
  •    60 g lime (calx) (3)
Prepare as with the fruit vat.

Start with hot water – almost boiling. Add the indigo to the vat, then the ferrous sulphate, then the lime. Wait for the vat to turn yellowy-green. Check for the bronze surface and the dark bubbles. Begin to dye with short dips (10-15 minutes). Oxidize in water and then the air.

These organic vats were originally developed by French dye chemist and botanist, Michel Garcia. Michel has been teaching and lecturing at the Maiwa Textile Symposium since 2009. He has worked with Maiwa in India as a dye specialist, most notably at the 2011 Maiwa Masterclass. Michel and Maiwa founder Charllotte Kwon meet on a regular basis to conduct natural dye research, explore recipes and test procedures. Together they are always looking for techniques that give the most exquisite colours - made to outlast the fibres they adorn.

The Maiwa Guide to Natural Dyes

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  1. Once again you folks have put together and shared an amazing resource for the dyeing community!
    Catharine Ellis

  2. since i've not yet started dyeing with indigo, i'm confused about the different vats. this was called a cold vat because it can be kept for months, but then i assume it's reheated for dyeing? can't the vat made with fruit or fructose be kept and then reheated as well?

  3. The ferrous vat does not need to be reheated when you return to the vat after a period of time (the fruit vats do need to be reheated prior to dyeing again). In both cases you would check the vat to see it's condition and check the pH. If necessary you would adjust the vats (see the instructions) but you would adjust the ferrous vat cold.

  4. thank you so much for the information. is lime what i would add if the ph level needed to be adjusted? seems that this is the simplest way to dye indigo since an older vat doesn't need to be reheated. other then that, is there any benefit of dyeing with fruit/fructose over ferrous sulphate?
    i appreciate the help.

  5. Hi, yes lime is what you would add. As you work with the different vats you may develop a preference for how you like to work, what the vat smells like etc. Also depending on how you work you may find some vats easier to maintain than others.

  6. Oh, wow! Thanks so much for this. I have been having terrible trouble with my vat lately, I was doing well for a year or so but can't seem to get it going again, despite refreshing and adjusting pH. Any suggestions at all?

  7. Hi can I use synthetic indigo as well as natural?

  8. Yes, this vat will work with either synthetic or natural indigo.

  9. hello. I've been rinsing my yarn in vinegar after dips in the 1,2,3 ferrous vat, but I have not been using a ph neutral soap. I'm running into a problem with the vat's ph escalating (now at 13 or 14), and my yarn isn't getting as dark as I've seen others. Wondering if the absence of a ph neutral soap might be the reason for this, and/or if using vinegar could be causing the ph to escalate.



  10. Any suggestions on change in formula if I was handpainting with indigo and need deep shades? A common problem I have with chemically reduced indigo is that by the time I finish the painting (could take a day) and wash the fabric, the indigo looks eaten away. Any advise is much appreciated, Thanks.

  11. Hi,
    I was wondering if you stir the vat everyday to keep it from going bad?

  12. What is the ideal temperature range to keep a natural indigo vat in?

  13. I know this is an old post, but when it is time to readjust the vat, do you need to add the ingredients in the same amounts as originally, or just in the same proportions?


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