Overdyeing With Mimosa Hostilis: Purples, Rusts and Greys

One bark gives one family of color. Two dyes used in turn give a whole palette, and Mimosa hostilis is a good partner because it sits in the red-violet part of the range that few other natural dyes reach.

How colors combine

Natural dyes layer the way watercolors do: each one filters the light, so the result is darker than either color alone and sits between them. Pale layers give clear mixed shades. Two heavy layers move toward brown, so keep at least one of them light.

Take the table as a starting point. Fiber, water and the strength of each bath all move the result.

With indigo

Indigo is the classic partner, because a true purple is hard to get from one natural dye. Indigo needs no mordant and is dyed in an alkaline vat, and alkali shifts the color of this bark. For that reason many dyers dip the indigo first, rinse the wool very thoroughly, let it air for a day, and then mordant with alum and dye with the bark. The other order works too. Dye two samples, one each way, and keep the one you prefer.

With a yellow

Dye the yellow first on alum-mordanted wool, then put the skein through a weak Mimosa hostilis bath: a second or third bath from bark you have already used is ideal. Pink over yellow goes peach and coral quickly, and rust if the bark bath is strong. Getting a second and third bath from one batch explains how to keep used bark for this.

With sassafras

Both barks are rich in tannin and both like the same alum mordant, so the order matters less. A pale pink dipped in sassafras turns rosewood. Dyeing wool with sassafras root bark gives the sassafras bath.

With iron

Iron is a modifier and not a dye, but it belongs here because it is the quickest way to turn one bath into several colors. A short dip in a weak iron bath takes rose to grey-violet and plum to slate. Use very little, in its own pot. Iron as a modifier, and how far to go has the amounts.

Rules that save wool

• Mordant once, with alum, before either dye. One mordant serves both.
• Rinse thoroughly between dyes. Whatever is left on the fiber goes into the next pot.
• Keep the bark bath under about 175°F (80°C). Heat browns this color, and brown over another dye is mud. Keeping a bark bath purple explains why.
• Sample first. Ten grams of yarn through both baths tells you more than any chart. Testing a dye before you commit a fleece sets out the routine.
• Write it down. Note both dyes, both strengths, the order and the times, so that a color you like can be made again.