How to use natural mordants

Mordants play a fundamental role in dyeing and we are often asked for advice. We have been lucky to get guest blogger Lucy Lepchani to step in to fill the huge void between what we know, and what we wish we knew. Lucy explains her approach to this huge topic, and shares with us some of her experiences with natural mordants.

Everyone uses mordants differently and it can take time to understand your material, your additives, and your methods. From wool to silk, hot to cold, acid to alkaline, your results can be turn out as polar opposites.

“I have stuck with the least toxic and most affordable/accessible [mordants] so far, which are salt, vinegar, tannin from rhubarb/blackberry/oak leaves, alum (bought as a powder) soda ash/washing soda, and iron. Some dyes don’t need mordants: lichens, turmeric and oak.

How I use them: first, make sure the wool is washed of any commercial fastening or detergent. careful not to felt it in the process – heat is OK – agitation makes felt. You can use soda ash but I hate how it makes wool brittle. Iron is my favourite: keep some rusty nails or steel wool in a jar of spirit vinegar. After the wool is washed and rinsed, or, as I do, after the dye is in the pan, add a good sloosh (I am so slapdash, a sloosh is a small wineglass full) of iron mordant and let the wool soak for ages and ages – ages x 2 meaning a few hours or a day.

Using alum must be done in advance – I use it with all kitchen ingredient things (not turmeric) but it must be used in equal parts with cream of tartar or th wool is horribly sticky.

Iron makes colours slightly murky (I love these) alum makes them quite as-they-are, and I hear that tin and copper make the colours brighter but I haven’t made natural versions of them yet. I want to. That will involve copper in vinegar, and tin likewise. Slooshes are my mainstay of amount, I have yet to discover how they work. I have just ordered a teeny amount of copper sulphate to save time/see if its worth the trouble of using copper in my palette. If so, I will be harassing plumbers for their leftovers forever.

Also – vinegar brings out the red in colours, bicarb accentuates blue. With an alum mordant, you can get a range of pinks, mauves and blues from red cabbage. salt is my go-to if I’m having self doubt about a mordant, I just add a teaspoon or so into the mix.

You can check out Lucy’s blog here, and our range of natural dyes here. Thanks for the inspiration Lucy.

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