Fermentation dyeing, how to start…

These last couple of weeks I had some people asking me to explain how I make fermented dyes.

fermented shades

the results of fermented dyes from a couple of years ago

The thing is… I’ve changed and adapted the way I used to dye. These last months I’m  in the process of developing my own technique which is similar in a sense but very different too. But it’s too soon for me to explain how I do it exactly as I really need to do lots and lots of testing before I can explain anything. This will take several months. I’m planning to write a book about it. But because it doesn’t seem fair to post results of my experiments and not telling people how to do it. I’ve decided to repost an older blog post where I explained the fermentation technique I’ve used for so many years now. It’s a excellent base to experiment with all kinds of dye-plants and to learn to understand the fermentation process. So here we go:

The fermentation dye method was invented or rediscovered by Madame Anne Rieger, a French woman who works and lives in the South of France since 1954. She works with plant dyes only by fermentation, without boiling and without mordants.  It’s known as an old dye tradition which was in use in Europe before the Renaissance period. As far as I know she didn’t write a book or anything and she is not on the internet, which is a pity because she really is an expert on the matter. Anyway, I’m told she did changed her method since then. Me, I just tried her method after I read some articles from an old magazine from the eighties. I’ve been experimenting with this method for more than ten years now, mostly with plants that grow in my back yard. I always work very intuitively. The method described here is a basic one and everyone I know (mostly French dyers) who are using the fermentation technique to dye their yarn with, have developed their own variations which are all slightly different to the original technique.

You will need:

Big plastic bottles for the plant to ferment. One for each plant you want to experiment with. For every fermented herbal dye you need two glass jars which can be sealed. One for a basic vat and one for an acidic vat. 3 liter glass jars are perfect because you can easily put one to three 100 gram hanks of yarn in it. A big plastic bucket, a fine cloth and a large plastic mesh strainer to strain the liquid. A digital pH meter. This is the only instrument you really need.  The measuring of the different pH levels is important with this method. You can find one at an aquarium supplies store. You will also need lemons or vinegar for the acidic vat, lemon juice is the best (acidic). Wood ash lye water or washing soda or slaked lime for the basic vat (alkali). And of course you need yarn to dye, wool or silk. This method is to dye wool and silk only. You don’t need mordants or metals but don’t expect extremely bright colours like with synthetic yarn! You also need a lot of patience…

How to make wood ash lye water:

Lye is caustic, so please take the necessary precautions. Gather some wood ash from the wood burner or fireplace, filter it trough a sieve to obtain fine ashes, fill a large plastic dustbin half with the ashes and half with rainwater or water from a well, let it rest at least 36 hours and stir several times a day. Pour this liquid trough an old cloth to filter it. (please use gloves). You can use this lye-water now for the basic dye-vat. This can be used for two, three months.

To start a fermentation you use a large plastic (or glass) bottle, I usually use 5 liter water bottles. Important: it has to be sealed, so you need a thight shut lid. Now, fill the bottle for two thirds with the plant material of your choice (fresh or dryed material is ok) and then add water, not tap water, preferably rainwater, distilled is fine too or water from a well. You fill the bottle but not completely, because we want this liquid to ferment, and fermenting means: gas = extra space ! Shut the lid. Put a label on the bottle with the date and the name of the plant. Let it rest in a warm place, outside if it’s warm enough, behind a sunny window if it’s too cold, in a green house if you have one or next to the stove in the winter. The liquid needs to ferment in the shadow or even in the dark, so covering it up with black plastic when put in direct sunlight is good. We don’t want to do solar dyeing but we do need some heat otherwise the fermentation will not start.

plant fermentation vats

Every day you shake the bottle well, then open the lid a bit and shut it again immediately. When it start to say: Psschhht… the fermentation has started. This has to be done daily till the Psschhht stops, which will take several days or even weeks, depending on the plants or on the weather! Normally it will take one week or two. You have to keep an eye on it every day during the whole process. If there is any mold entering the vat, it’s ruined. When fermenting starts it also starts to smell. You will have to get use to this smell ! But know that after washing the yarn with some soap there won’t be a smell left.

If you have followed the instructions you should have a fermenting vat by now. There should be a colouration of the water which can give some idea of the colour this particular plant yields, this colour will darken throughout the process. There is a smell which cannot be a problem if you keep the vat closed.  Don’t forget to open the vat at least once or twice a day especially if it is very hot and/or if there is thunder in the air. Fermentation in glass bottles is therefore a bit tricky as there is a risk of explosion if the bottles are not opened several times during fermentation.

This fermented herbal dye liquid can now be sieved into a bucket. Squeeze the plant material through a cloth to obtain more dye “juice”. The leftover plant material can go into the compost heap. Now you will have to do some switching between acid and basic (alcaline) dye-baths.

A and B vats – dyer’s chamomile, safflower and coreopsis

After the fermentation, the actual dyeing: Pour half of the filtered liquid in one of the glass jars (A) and the other half in the second jar (B). No more than two third of the jars can be filled, because there has to be place left for the yarn. Now you need to check the pH level of the dye with a digital pH meter. Knowing that 7 is neutral, we will now adjust the pH to make jar A lower and jar B higher. Add a bit of lemon juice (or vinegar) to jar A (acidic) to drop the pH level. Notice the change in colour ! Measure the pH level again and put some more lemon juice till the pH has dropped under 4. Between 3 and 4 is ideal! Depending on the plant you will need different quantities of lemon juice to lower the pH level. In jar B (alkaline) you will now slowly add lye water, not too much at once, the basic vat need more time to adapt to the higher pH level. The colour will now darken. You can add more lye water, spread over several hours or days. The highest pH level for wool and silk should be 9, 10 is ok too but 11 is too high ! Now put the yarn you want to dye in jar A, let it macerate at least one day but several days to one week is better. Take the yarn out of jar A, gently squeeze the liquid out of it and let it dry outside (there will still be some smell!) in a warm place but not in direct sunlight. When the yarn is dry put it a few minutes in the alkaline vat ( jar B) , but no longer than 15 minutes, the color of the dyed yarn will get darker. Take the yarn out of jar B, squeeze the yarn gently (use gloves) and let it dry again. If everything went well, you have now dyed your yarn with a beautiful colour 🙂

If you want to have a deeper colour you can repeat the operation again: first jar A then jar B. Sometimes, depending on what kind of plant, you can stop with the second acid bad and sometimes you can stop with the second alkaline bath, which will give different shades. But the first step is always as described above.  Important: You will have to re-check the pH level after every step and adjust it with lemon juice or lye water. At some point the dye will be exhausted, put both liquids together to neutralise the ph, this liquid can now be trown outside without fear of harming plants or animals.

You can also use vinegar instead of lemon juice for the acidic vat . For the alkaline vat you can also try adding some slaked  lime or washing soda, experiment with it. I don’t recommend using amonia though, never using it myself anyway.  When the yarn is dyed and dry you will have to wash it in a mild soap bath and rinse it in soft water before drying it for the last time.

Experiment for yourself with different plants !


different shades of madder

In the meantime I will continue to post pictures of my own dye experiments. I hope to have my book finished after the summer months.

Thank you for visiting…