Naphthoquinones, these are wonderful stable yellows and browns. Unlike Flavonoids, there are not many plant species that contain naphthoquinone.
Naphthoquinone subgroups are;
Plumbagin (walnut drupes, Indian leadwort)
Juglone, found in all species of the walnut family (Juglandaceae). This includes trees such as black walnut, butternut, hickories and pecan. Black walnut hulls have the highest concentration of juglone.
Juglone from walnut trees itself is toxic to plants, so much so, that there are only a few plants that are able to grow in its' proximity. The phenomenon of trees that use toxins to stunt competing trees' growth is called allelopathy.
All juglone containing trees are great for natural dyeing and also a great fit for eco printing. Pecan leaf botanical prints are my personal favourites on all types of fabric.
The walnut and pecan leaves have a lot of tannins, and their prints tend to turn darker over time. Dyeing with walnut and pecan hulls or leaves do not require a mordant at all, when you do mordant with alum it will bring out more of the golden tones and mordanting with copper will bring out rich darker golden hues. Post mordant with ferrous sulfate for dark brown to black shades. Fermented black walnut hulls with ferrous sulfate and gom arabic make for a great lightfast ink.
Lawsone aka hennotannic acid: henna (Lawsonia inermis).
Traditionally used for temporary tattoos and hair dye it will turn orange when it is oxidizing on protein (such as the skin of your hands, or hair).
Henna needs no mordant for dyeing. It works better with an acidic dye bath (just add a bit if lemon juice), and will continue to develop its color well after dyeing, turning more saturated under the influence of light and warmth. This is because henna’s dye molecule, lawsone, oxidizes. This means that it reacts with the oxygen in the air to achieve its final, stable state. When henna powder is mixed with an acid, the precursor of the lawsone molecule is released in an intermediary state, ready to attach itself to something. This molecule is called an aglycone.
Henna can be used with the Low Impact Dye technique using only a sludge and manually working it into the fabric as opposed to making a dye bath.
Another way henna is used is as a reducing agent in an organic indigo vat.
Achieving black on wool with henna and green indigo; first step; use henna in an acidic dye bath for a few hours. Second step; apply green indigo with the Low Impact method on the rinsed fabric and let it sit for a good 30 minutes in the indigo sludge.
