It was a pleasure to return in June to the Bedfordshire Guild of Weavers, Spinners and Dyers, of which I was a member for over thirty years before we moved to West Sussex. The occasion was an indigo workshop I was leading and I was delighted to see old friends and to meet some new members.
To demonstrate the various sources of indigo dye, I made several vats using natural indigo, synthetic indigo, woad leaves, woad balls and stored woad solution.
I used the Colour Run Remover recipe given in my books with the synthetic indigo. However, as Colour Run Remover is not always easy to find in powder form (the liquid form isn’t suitable for indigo vats), I decided to try a different method with natural indigo. I was looking for a simple method and, after some experimentation, it seemed that using equal quantities of indigo powder, washing soda and sodium hydrosulphite (hydros) would work well. An added advantage is that using equal amounts of each ingredient makes this a very simple recipe. As indigo reduces better in a more concentrated solution, I decided to make a stock solution on the day before the workshop. To do this, I mixed 4 teaspoons of natural indigo powder with very hot water to make a paste. Then I dissolved 4 teaspoons of washing soda in very hot water in a strong glass jar, added the indigo paste and stirred well. I added more hot water until the glass jar was just over three-quarters full then, after checking that the temperature was not above 50C, I carefully stirred in 4 teaspoons of hydros and put the lid on the jar. I then placed the jar in a saucepan of very hot water and put this on a hotplate overnight. In the morning I checked the pH and added more washing soda to bring it to pH9. The solution looked a murky greenish yellow at this stage. When I arrived at the workshop, I filled a stainless steel bucket with very hot water (but no hotter than 50C) and added 2 teaspoons of washing soda and two teaspoons of hydros. I then gently added the contents of the glass jar. The vat was allowed to stand for about 20 minutes until the liquid below the surface was a clear greeny/yellow. (If this seems to be taking too long, add some more hydros.) This vat is very simple to make and worked well. However, I intend to experiment further to see if I can improve on this method.
Both of the indigo vats produced dark blues immediately and those students who wanted paler blues had to wait until some of the blue had been used before dyeing their samples. I also suggested that the wool samples should be dyed first, while the vats were hot, and that the cotton and silk samples should be dyed later, when the vats had cooled down. This is because wool takes up the indigo dye better in a hot solution, while cotton and linen prefer cooler solutions.
With the woad balls I used the recipe given in the revised edition of “Wild Colour” and also in an earlier post on this blog. Unfortunately, the woad balls only produced a pale blue and not enough for all the workshop participants to dye their samples. I think the balls probably needed to steep for a longer period than we had available. We also had limited success with the fresh woad leaves, which gave very little colour. However, I suppose this was to be expected, as June is really too early to harvest the first year leaves, which hadn’t had enough time to develop their colouring potential. The woad solution, which gave deep to mid blues, was from 2008 and worked very well, so this proves (if proof is necessary) that correctly-prepared woad solution can be stored successfully for several years. The recipes I used for these two woad vats were those in my books.
The photos below show some of the materials dyed by students at the workshop.