Journal

Dyeing wool with bracken - an experiment in changing the pH

Last year - when I was busy dyeing pieces of vintage linen - I fell down the rabbit hole of Eastern European methods of dyeing cloth with bark. The process was a long one of soaking and heating the bark over a number of weeks, but also involved changing the pH of the dye pot so that it was alkali. The amount of dye - and the colour - were both transformed by this and I got some deep burgundy pieces of cloth.

This year my personal project is a range of 20g skeins of double knitting weight wool which I am dyeing with plants from the garden and verge. I am dyeing four skeins with each plant - two where the dye has been extracted in pure rainwater which is neutral and two where the dye has been extracted in an alkali solution of rainwater with a spoonful of washing soda.

I have a notice above my dye bench saying ADD THE VINEGAR - for if I put the wool into an alkali solution it would be damaged. I add a slug of vinegar to the alkali mixture and test with indicator paper to ensure it is back to neutral before adding the wool.

I then modify one of each batch with iron - ferrous sulphate - for five minutes.

With some plants there is hardly any difference, but with others it is really marked, not just a saturation thing but a completely different colour range. Bracken was particularly striking.

I gathered a lot of bracken - green leaves full length - and divided it into two. One part I simmered for an hour in rainwater and left to soak overnight, the other I simmered in rainwater and washing soda and left to soak overnight.

In the morning I drained the bracken out and added a slug of vinegar to the alkali pan - checking with indicator paper that it was back to a neutral pH.

In the meantime I had mordanted four 20g skeins of wool, soaking them overnight in water with 8% weight of the wool of alum.

I added two skeins to each dye pan - gently heated them to about hand hot and then left them to cool.

When they were cool I added one from each pan (remembering which was which - been there, done that, forgotten completely) and added it to the iron pan - which has rainwater and ferrous sulphate in it.

I left them for five minutes, took them out and rinsed very, very well.

The skeins were all dried, left for a week in a box, washed, dried again and gave these results.

The alkali dye bath gave a rusty pink and a very warm grey whereas the neutral dye bath gave a chalky yellow and a really nice dull green. As colours they go together beautifully.

You can get a free downloadable pdf tutorial about dyeing wool yarn with bracken by signing up to the library

You may also enjoy …