Dyer's Greenweed, Dyer's Broom, Dyer's Mignonette, Dyer's Whin, Waxen Woad and Waxen Wood are all names used for the same dye plant known in Latin as Genista Tinctoria.
It was often used in dye houses as substitute for Weld, when weld prices were too high. In the 17th and 18th century, Weld prices were linked to wheat; when wheat prices went up because of worldwide shortages, European farmers would prefer to grow wheat in place of Weld, subsequently leading to price increases for the dye stuff.
Edward Bancroft mentions it only briefly in his book, Berthollet writes in "Elements of the Art of Dyeing"; ...which grows abundantly in dry and hilly grounds, yields a yellow colour which can not be compared in beauty with that of weld and saw-worth, but it acquires sufficient permanence by means of mordants.
It is a small tufted shrub growing 60-90 cm tall and is deciduous, meaning it needs to be harvested while in season which is from spring to early fall. It grows wild and cultivated, in sunny areas in the mediterranean. Sometimes it gets mistaken for Scottish or Spanish broom but those are both taller than the Genista Tinctoria (they dye as well, but need higher WOF).
In natural medicine the shrubs flowering twigs are used to cleanse the body of toxins. For example, it is thought to work as a cathartic, cleansing and purging the intestines like a natural laxative. It is also thought to cause a person to sweat excessively as well. I have not tried this myself, as I prefer to dye with my materials, rather than make a tea out of them.
The active dye compound in the plant is isoflavone genistein, as well as smaller levels of flavone luteolin and apigenin. Together they make for a moderate good lightfastness on well mordanted fabrics. The Genista Tinctoria available in our webshop is grown and processed in France.
For this dye process I first mordanted all of our samples in aluminium tri formate, you can read about this aluminium mordant here. I am now leaning towards mordanting all of my fabrics cold, to save natural resources. Another added advantage I have found, is that the cold mordanting can be done in a bucket that is permanently on the floor and saves me a lot of heavy lifting. Always rinse fabrics after mordanting, it's good practice for logical reasons; mordants attract dyes, so you want the mordant to be attached to the fabric only and not to float around for no reason in your dye pot.
I used around 30% WOF of dried Dyer's Broom.
After reading this extremely informative blog by Catherine Ellis, I now understand that the yellow dyes are more or less acidic and the acidity inhibits the dye from adhering properly to the fabric. The dry dyestuff could use a little soaking before heating but of course, I am way too impatient for this so I just cranked up the heat to get it going. I assume solar dyeing would not be bad for this either.
I made two batches of dye to decide if I want to make it a regular practice to add chalk to the dye bath to neutralise acidity, so there is one with and one without the chalk.
I stopped boiling any dyes, unless I forget the pan on the stove. I heat to below a simmer for around one hour and let it cool after that.
Right; without chalk
Left: with chalk
Dye results after dyeing for about one hour, rinsing and drying, at some point I will learn to use a dye bag and not waste so much time picking out the bits and pieces. A proper dye studio would help as well...but I digress.
Weld has a tendency to be a bit blotchy on silks, and Dyer's Greenweed does not have this as much.
A close up side by side comparison per type of fabric. All mordanted with aluminium tri formate, cold in he same mordant batch.
I am very happy with the HAPPY yellow this gives me. Not leaning towards green like some do, or on the brown/orange border of Marigold. Just a plain, happy yellow.
Adding chalk is going to be standard practice for yellow dyes for me from now on, I had the impression it assisted with getting more yield from the dye stuff but that claim would need further investigation with exact measurements.
On a personal note: These are strange Corona times, and I can not explain how happy I am to be just dyeing my little samples and seeing them sway, drying in the warm afternoon. A small reminder for me to not take anything for granted, ever.
Happy dyeing to everyone, wherever you are.