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By Elska á Fjárfella (Susan Verberg).


Left to right: undyed, goldenrod, nettle, onion, onion (longer), iron – all unmordanted wool.

Having laid my hands on half a dozen skeins of plain white wool yarn, and having the resources of a homestead, I decided to combine the two under the guidance of my friend Angelika and try my hand at all-natural plant dyeing.

But where to start? And what to buy?

Isn’t dyeing quite an intricate and expensive challenge better left to the experienced and initiated?

In part that is true; it is quite handy learning to dye from someone who has done it before.

But it does not have to be difficult or expensive at all (it can be as intricate only as you decide to make it). If you’re looking for a specific shade and want to be able to duplicate, my way is not the way for you. But if you’re happy to get color — and even happier if it is mostly the color you intended — you can get a surprising amount of dyeing fun out of an ordinary backyard.

We both prefer natural fibers so we used a selection of linen, cotton, and wool fabrics and fibers. I quickly learned that plant-based fibers and animal-based fibers do not take color the same way. Plant-based fibers are made from cellulose, which is fairly resistant to taking dye. Animal fibers are made from protein and are relatively easy to dye. Both need a little help to create a good connection between fibers and dye; this process is called “mordanting.”

From looking over Angelika’s shoulders and listening to her explanations the past few years (she loves dyeing with natural materials), I picked up that some dyes need mordanting, some fibers need it, too, but not always or in the same amounts… but why? As it turns out, most fibers and dyes are not all that compatible because there isn’t a lot for the dye to adhere to. So to give the dye a place to stick, something is added that bridges or sticks both to the fabric and to the dye.

In the case of cellulose fibers, a tannin mordant is needed, followed by a metal mordant; in the case of protein fibers, a metal mordant is enough. It is possible to dye wool without mordants but the result won’t be as vibrant; onion and tea are high in tannin and will dye, but mordanting influences the intensity of color. Black walnut is a bit of an odd one since it does not need mordanting because it is high in natural mordants; however, the chemical structure of the pigment allows it to directly adhere to the protein fiber!


Processing sumac leaves to make a tannin mordant.

Two good sources for tannin mordants are sumac and rhubarb leaves. Since rhubarb is easily available in spring and sumac easy to find in summer and fall, these two make a good three-season source of natural tannin mordant. With both sumac and rhubarb the leaves are used, not the wood; for each pound of dry yarn use four pounds of greens.

  • Put leaves in a big pot, cover with water, bring to a boil, and boil for an hour.
  • After an hour remove the greens, add the cellulose yarn and let sit for another hour, or two.

Another source for tannins would be black tea, but as that is highly concentrated it would also act as a dye and darken the yarn significantly. Sumac does too, but not as significant and therefore does not interfere with the dyeing process as much, making it a better tannin mordant for brighter colors (and it’s free).

A good metal mordant is alum, or aluminum sulfate, which is fairly inexpensive and sold over the internet at stores specializing in dyes. Use 10% for wool or up to 20% for fine yarn like silk, cotton, or linen, of the dry weight of the yarn.

  • Add enough water to submerge the yarn, bring to a boil, turn off, add the damp yarn and let steep for an hour, or so.
  • Do not boil fibers, especially wool roving and tips, as the roiling bubble action of boiling can naturally felt it!

Mordanting the fibers in sumac ‘tea’ overnight

Mordant the evening before and let the yarn sit in the mordant overnight; that way, the yarn is cooled down enough it can easily be squeezed or wrung dry for the next step, the dye bath. Keep in mind that each mordant results in slightly different color dyes, so choose accordingly. For instance, chromium really brightens colors (but is poisonous), alum gives clear colors, tin brightens colors and can also be used as an afterbath (adding it to the dye late to darken), copper gives the best greens and iron darkens, and is often used as an afterbath. Both copper and iron can be made at home: copper can be added by dyeing in a copper pot, and an iron solution can easily be made by adding vinegar to iron scraps (like nails and pieces of cheap fencing) in a glass jar… but be careful not to screw down the lid as the exothermic reaction might respond unexpectantly!


Harvesting stinging nettles is quite a prickly business!

Using plant materials it is not all that difficult to dye yellows; pale yellow, lime yellow, greenish yellow, brownish yellow – most plants give some sort of yellow dye. Like ragweed dyes a greenish yellow, birch & poplar dyes yellow, any of the rosacea leaves dye yellow, peach & apple leaves dye yellow and bindweed dyes a light green yellow. It’s the other colors that are harder to find:

  • Onion skins can dye a bright orange.
  • Reportedly,bindweed roots dye a slight pink, as do rhubarb roots (but I’m not digging up my patch!).
  • Willow leaves and bark dye a cinnamon brown, black walnut a deep brown at first draw and a cinnamon brown at the second.
  • We also tried some odd ones like daffodil heads (yellow) and tageta flowers (also yellow) and honestly, if there is any indication of dye (it stains your fingers while weeding) get a bunch, boil it down, and see what happens!

Harvesting goldenrod flowers to make a bright yellow dye.

Except for a few dyestuffs, like goldenrod, most dye baths benefit from prolonged exposure. A good rule of thumb is to make your bath in the afternoon, add the yarn, put the colander with greens on top of it (keeps the yarn submerged and keeps steeping more dye) and let it sit overnight. You’ll benefit from the cooler evening temperatures to cool down your kitchen again and as an added bonus the yarn is nicely cooled down by the next day to easily be rinsed in cold water without starting a felting reaction. Let it dry, or set, completely – out of the sun – before washing with soap.


Goldenrod dye with unmordanted wool yarn (top left) and alum mordanted wool (top right).

In the case of goldenrod, the flowers give the bright yellow color and are a potent dye. The longer it sits, though, the deeper the color gets and at some point the green stems and small leaves, which dye brown, will add, making it even darker. So for a bright yellow 15 minutes tends to be the optimum time. Similar with onion peels; sitting overnight can darken the orange towards brown. Black walnut is also a powerful dye and needs no mordanting at all for wool fibers, making it a good beginner’s dye. It also has antifungal properties and was used for wool underclothing throughout history to help prevent skin conditions!


Onion skin dye with alum mordanted wool fiber and unmordanted wool yarn.

For my first project we used well known dye plants like black walnut leaves, goldenrod flowers, stinging nettle and onion peels. We could have weighed the greens, but as our limitation was space in the pots, not the amount of greens, we picked as much as we could fit into each stockpot. As I could fit three stockpots on my stovetop we made three dye baths at the same time, in a similar fashion as the mordant solution: cover the greens with water, bring to a boil and boil for an hour, or so. Remove the greens, turn off the heat, add the yarn – and see the color change…

We dyed plant fibers and protein fibers and got wildly different results – both between the two types of fibers and from what we expected and what actually happened. Unless every variable, including temperature, pH & weights, are carefully controlled, natural dyeing is quite the spontaneous undertaking! For instance; a linen dress I was hoping to dye a deep brown with black walnut turned into a beautiful yellow copper instead – linen really does not take dye very well. A cotton dress I was hoping to dye yellow with logwood turned blue instead! The wool was mordanted in an acidic environment (an alkaline can damage wool fibers) but not rinsed really well, acidifying the dye to a pretty yellow brown. But when we made a new batch and added the cotton dress it was naturally alkaline and dyed a deep blue!

We sure saw chemistry in action: what a difference the nature of fibers makes, how some dyes react to changes in the pH but others not at all, the color difference a bit of metal mordant makes, how some strike enthusiastically quick but others need soaking overnight… to get a taste of all the intricate variables possible while still being such a surprisingly easy and rather satisfying project… I totally see how natural dyeing quickly can become quite the passion!

See Elska’s blog here for the rest of her dyeing adventures.