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Natural Dyeing – Mordants and Modifiers

October 3, 2016

A couple of weeks ago in the last throes of summer we had a Natural Dyeing Day lead by guild member Susan Dye. She had prepared a challenging programme that would lead us to examine 3 dyes, 3 mordants and 2 modifiers leaving us all with 27 samples to take home. Phew! Lots to do then!

We started with a health and safety briefing which was taken quite seriously when it involved a cautionary tale of pets interacting with toxic substances and having to be rushed to the vets for treatment. Wear gloves. Don’t breathe the fumes. Cover dyebaths so small, inquisitive creatures can’t get to them. Read the safety leaflets and store your chemicals carefully.

The mohair yarn was pre-mordanted with alum or copper sulphate or iron sulphate. The alum left the yarn white but with a different texture, iron left it reddish and copper a light green.

We then had to make the dyebaths, the madder was easy as this was a prepared powder, but the weld and dahlia dye had to be extracted from the plant material first.


From there the skeins of yarn went into the vats, to cook gently:

In the afternoon we split the skeins into the groups, unmodified was hung up to dry, whilst we then prepared the acid and alkali modifiers. We used citric acid and ammonia as the modifiers, adding these to the dye baths.

We did experiment a bit, adding more acid or alkali when not a lot seemed to be happening.

We found the acid seemed to strip away the colour, whereas the alkali deepened the colour for some. Some quite dramatic effects with the dahlia and madder especially.


Top row is unmodified, left to right 3x madder, 3 x dahlia, 3x weld each with the alum, iron, copper. Second row is acid modified, third row is alkali modified.

At the end of the day we had some more cake (thank you everyone who brought food) and divided up the yarn and displayed it beautifully:


Thank you to everyone who came along, Claire for hosting us, and Susan for giving us the benefit of her experience in natural dyes.

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