I went to a girls’ grammar school where they thought it was appropriate to spend 4 years studying Latin but only about 6 weeks studying chemistry. Consequently, I don’t even know what the periodic table is – and it seems like a powerful gap in my knowledge (although luckily I know how to decline the Latin verb ‘to advise’). This can be a bit of a drawback when trying to work out the effects of different natural dyes and substances. Maybe it’s also why I’m not good at keeping records which is really important when you’re dyeing.
So, this month I decided I’d do some proper experimentation and recording. Jenny Dean in her wonderful ‘Wild Colour’ dyeing book explains an experiment where she produces 25 different shades from the same dye pot using madder root. Not quite so adventurous I decided to go for 10 different shades using turmeric root (or rhizome) and pomegranate rind. Turmeric root isn’t very lightfast and dyers in India have traditionally used it alongside pomegranate skin to make the yellow more long-lasting. If you want to know more about the chemistry of turmeric root you can read about it here. Apparently, the pigments are curcumin (E100) and other diaroylmethane compounds but I really don’t know what that means.
You can either use the chopped up turmeric root or powder (just the supermarket variety). It’s known as a substantive dye which means you can use it without a mordant. I decided to try it both with and without a mordant.
I wound 10 equal skeins of wool, weighed them and recorded the weight and then soaked them in water for a few hours. Then I mordanted half of the skeins with alum sulphate (not toxic or poisonous but it is an irritant so needs to be handled with care). The Wild Colours website has good instructions. The skeins weighed around 25 grams in total so I used half the weight of turmeric powder (13 grams) and the skin of one pomegranate.
Note: When I opened the container of turmeric powder I had to stop and wash my favourite hand-knit jumper as I’d omitted to wear an apron and the powder sprayed over the jumper – not a good start!
I simmered the turmeric powder and pomegranate rind for about 20 minutes in water, let it cool, then strained it through a sieve lined with a piece of cloth. I carefully labelled the alum mordanted skeins and put them in the dye bath along with the unmordanted skeins and slowly brought the dyebath up to simmering point. the skeins were simmered for 20 minutes, left to cool in the dyebath and then rinsed thoroughly. Apart from the jumper incident I was doing fine.
I put one each of the mordanted and unmordanted skeins on one side and proceeded to work on (or modify) the others in pairs of mordanted and unmordanted wool. I made an alkaline solution using washing soda as a modifier, and an acid solution with vinegar as a modifier. For each I added the modifier to water and slowly heated the skeins. The washing soda modifier turned the skeins more orange, the vinegar modifier didn’t really change the colour but brightened it a little.
For the next bit of experimenting I used copper and iron modifiers. Both of these were made by soaking copper piping and rusty iron nails respectively in a solution of water and vinegar for several weeks. The copper liquor is poisonous so has to be stored, handled and disposed of with care. The same method of modification is used as for the washing soda and vinegar modifiers. Judging amounts is difficult but only a very small amount is needed to alter or modify the colour. The copper brought out green and the iron an even darker green.
So, I got my results even though my chemistry knowledge hasn’t really improved. I feel a New Year’s resolution coming on…!