Among some natural dyers, tansy is seen as quite boring. It’s a common plant, easy to find, easy to dye with, and it contains the so-common yellow – just like so many other plants. But tansy has a long cultural history, and its yellow dye is of high quality!
Tansy’s common name is simply an abbreviation of its latin ditto, Tanacetum vulgare. I recently ran into a nice (and plausible) explanation of the name in an old Danish book by an important author on natural dyeing, Esther Nielsen. She writes that Tanacetum is probably a derived form of Athanasia (a-thanasos means immortal). Supposedly, the immortality is a reference to the fact that the flowers keep their strong yellow, also when dry.
Tansy has been used in herbal medicine for centuries. The plant is poisonous, especially to insects, and was used against intestinal worms. Today, eating tansy is not recommended, and it’s now known that its toxicity comes from the alpha-thujone content in all parts of the plant.
Nevertheless, it was used as a herb in the past, and it does have a very strong smell. I usually boil tansy dye baths outside!
As a natural dye plant, tansy has a lot of advantages. The plant is very common, so you’ll find it growing at just about any roadside – at least here in Denmark, which is in tansy’s native range. Since the plant is so common, it’s completely fine to harvest as much as you need, as long as you cut the flower stalks of, leaving the rest of the perennial.
The yellow color from tansy is very light fast, in my light tests, it always comes out as more fast than weld yellow, which is known for its good light fastness.
According to this paper (Phytochemistry 51, p. 417, 1999), tansy flowers contain a lot of apigenin and luteolin, the same yellow dyes that you find in weld. The leaves contain slightly different compounds (that are similar to luteolin, but not exactly the same). So it makes perfect sense that leaves and flowers give slightly different yellows. I’m not sure, though, why the light fastness of tansy yellow is better than that of weld yellow in my experiments…
After reading about dye extracts (somewhere), I decided to try making a tansy extract. Extracts are obviously a compact way to store dyes, but I thought that they might be interesting for other reasons, for example printing on fabric.
I even found a paper where the authors described concentrating tansy extract to the point that it became a powder. So this is what I tried:
500 g (just over a pound) of fresh tansy flowers and leaves (picked August 11th) were boiled in enough rain water to cover them. I left the pot until the next day, strained out all the plant material, then boiled the extract to concentrate it until it didn’t loose any more water. I also dried it in the oven at very low heat. And the result was a small amount of extremely sticky tansy syrup:
So my extract clearly didn’t turn into a powder, but a very dark and sticky syrup. Ages ago, in organic chemistry class, I was taught that syrup means impure product. But I guess that is expected in this case, since I just concentrated a crude extract of the plant, which is a mix of many different compounds.
To test my syrup, I simply dissolved it in water and used it to dye 100 g (3.5 oz) of wool (Fenris) instead of exploring more exciting options. I wanted to see how the dye was affected by being turned into syrup and back again. Here is a comparison with 100 g of wool dyed with 500 g of fresh leaves and flowers (left), 500 g of fresh leaves and flowers dried and then used (middle) and tansy syrup dissolved in water (right):
The picture above shows, that the color from tansy is the same, whether fresh or dried flowers and leaves are used. And that is good to know – drying does not affect the dye.
The skein on the right, dyed with tansy syrup, is a bit browner than the two others. But other than that, the syrup treatment didn’t really affect the dye potential. Next year, I want to explore plant syrups more!
But once I got started with tansy experiments, more followed. While cleaning up my dyestuff storage, I found some dry tansy leaves from last year (2016). I wondered if long storage would affect the color – in the picture above, there’s no difference between yellow from fresh and dried tansy, but I only stored the plants for a couple of weeks.
I also wanted to answer another question: In order to extract the dye, is it more efficient to finely crush plant matter, or is it OK to throw whole leaves in the dyepot? So I powdered some dry 2017 leaves in my mortar to see if the color intensified, and the result:
The skein dyed with powdered 2017 leaves has exactly the same color as the skein dyed with whole 2017 leaves, so there’s no gain by powdering the leaves. Luckily, since that process is really cumbersome. The 2016 and 2017 leaves don’t give exactly the same yellow, but very close. I don’t think this small difference is caused by an extra year of storage – rather, the fact that the plants didn’t grow in the same place, the difference in weather and harvest time might have caused the small difference in color.