The Why’s of Natural Dyes

Natural dyeing is a relatively straightforward process, but without an understanding of what goes on at each step, the whole ordeal can seem a bit like potion making: add this salt here, stir there, and hope for the best.

Dyeing feels all the more like wizardry when plants impart surprising colors. The pink is from avocado skins, and the blue is from black beans.

I can’t emphasize enough the importance of reading and cross-referencing several resources (print and digital) when diving deeper into natural dyes. The different opinions and perspectives can easily become overwhelming but do really prove the point that this art is personal and inexact. Each person will have a slightly different experience because of all the different uncontrolled factors at play.

Here we will go over the basic justification for each step of the basic dyeing process, and why you might consider deviating from typical practices. For the specific how-tos of this process, you can refer to the links at the end of this post.

The dyeing steps are as follows:

  1. Preparing the dyebath
  2. Cleaning the fiber (Scouring)
  3. Preparing the fiber (Mordanting)
  4. Dyeing
  5. Post-processing the fiber
  6. Drying

1. Preparing the Dyebath

The dye pigments in biological material are generally water soluble. (Indigo is the looming exception.) While working with dry material might stain your hands, it is much more likely to do so if your hands or the material are wet. In dyeing, we want to move the pigments from the organism to a medium in which the fiber can take them up.

A cold extraction black bean dye bath looks purple, but imparts blues to wool.

This is why dye baths are prepared with soaking the material in water. Most dyes work best with the help of heat to extract the most pigment, but time is also a factor. The beauty of natural dyes comes from the multiple pigment molecules present, and they may emerge from the organism at different time intervals. For example, tannin-rich plants like eucalyptus can have brown tones emerge after a longer period, but may yield a yellow or green with less time. Fennel, on the other hand, yields a yellow earlier, with sage and pine greens only coming through after 1.5 to 2 hours in some cases (and with the help of iron). These different colors all contribute to that “multi-dimensional” inner glow of color that natural dyes tend to give to fiber.

To control for pH and unknown solvents, it is generally recommended to dye with filtered or distilled water. You can lower the pH with vinegar to brighten red, orange, and yellow tones, or increase the pH with baking soda or ammonia to yield blues and greens. Red cabbage responds dramatically to changes in pH.

2. Scouring

Fibers often come to us smoothed out in some way. Part of what makes wool soft, squishy, and not staticky is the natural lanolin from the sheep. It’s like hair oil, and it helps make the wool water-resistant and smell all nice and sheepy.

Scouring helps clean the fiber by removing any chemicals or substances that would prohibit dye from sticking to the fiber. This ensures the dye will pick up evenly. Even plant-based fibers like cotton are coated with waxes from the manufacturing process. For wool, this step also opens up the cuticle of the hair to make it more receptive to pigment.

Unscoured cotton (left) dyes unevenly compared to scoured (right).

It is not uncommon for the scouring bath to look quite dirty at the end of this stage. All that gunk lives in fabric and fiber, which is why it’s so important to wash clothes after you buy them from the store, or block your knitted goods before you wear them!

3. Mordanting

The mordanting step is what allows dyes to stick to the fiber, and stay there. Unmordanted specimens will generally not be as color-fast (and so will gradually fade in the sun and with repeated washings) as those which have been pre-treated in this way. This step can be optional, as many dye materials can act as their own mordant if they are high in tannins, but many dyes are notoriously fickle (“fugitive”) without a mordant.

Rebecca Burgess shows the effects of copper (second row) and iron (third row) mordants on three plants.

Some tips for mordanting:

  • There is a great deal of debate about the toxicity of these metal salts, so it is best practices to work in a ventilated space and wear gloves.
  • Plant fibers benefit from a round of pre-pre-mordanting with a tannin solution, to really help the alum stick to the fiber (and then the dye to stick to the alum).
  • Iron (Ferrous sulfate) can be used as a pre-mordant, though too much can degrade protein fibers. It will result in “saddened” dye colors, darkening the dye to more browns, greens, or even blues.
  • Copper (Cupric sulfate) also deepens colors, often resulting in more vibrant hues, like with black beans.
  • Mordants can also be used during the dye stage or afterwards for post-dye-processing.
  • Mordant baths can often be used twice, so they can be saved for the next time.

4. Dyeing

This is the easier part! Now that the fibers are prepared and the dye extracted, this step involves combining the two, usually with the help of heat and for an hour or two. Not much more to it.

Toyon leaves left in the dye bath with the fiber

Some people opt to leave the dyestuff in the pot with the fiber to continue extraction. This may result in an uneven dye application.

Another option may be to apply heat at the outset, but let the bath and fiber cool overnight to really soak up every last bit of pigment.

Lastly, dyeing in a copper or iron pot can impart the same mordanting effect of this metal, which may be desired or not. Otherwise, it is best to work with non-reactive containers like stainless steel.

Remember that protein fibers will dry 1 shade lighter than their wet appearance, and plant fibers will dry 2-3 shades lighter.

5. Post-Processing the Fiber

This step is optional, but a trip through an iron or copper mordant in post can give the same effect as described in Step 3.

6. Drying

Before drying, we generally try to rinse excess loose dye from the dyed goods. Sometimes a drop of dish soap can help. After all, you’re likely going to wash the garment or fiber again at some point in its use, so don’t shy away from it now! You may just wind up with dye bleeding onto furniture or other clothing instead.

It is important to dry your dyed goods away from direct sunlight, as UV rays are known to degrade pigments of any kind. Try to avoid wringing things like wool, as that can stretch out the wool fibers and cause misshapen garments.

Turmeric is notoriously fugitive, rendering vivid golds at first, and fading quickly with sun and washing.

For more on the specific recipes for each step, refer to:

  • Maiwa’s Guide to Natural Dyes (internet resource)
  • This minimalist tea-dyeing tutorial from Apartment Therapy
  • This mushroom / lichen dyeing tutorial from the Puget Sound Mycological Society
  • Harvesting Color, by Rebecca Burgess, shares specific insight into many dye plant species, including how and when to harvest and process each plant for an optimal dye experience, and focuses primarily on wool and protein fibers.
  • The Modern Natural Dyer, by Kristine Vejar, nicely showcases the range of colors achieved from different plant and animal substances on a variety of protein and plant textiles. It also features many sewing, knitting, and shibori projects.
  • Natural Color, by Sasha Duerr, features seasonal projects and dye instructions to take advantage of nature’s bounty.


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