Mimosa Hostilis Root Bark Powder
Botanical use only
$37.501/4 lb
To eco print silk with Mimosa hostilis, dye a cotton blanket or the silk itself in a bark bath, lay mordanted leaves on the silk, roll it tightly around a dowel, and steam the bundle for about an hour. The leaves print dark on a plum or rose ground that the bark provides.
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Eco printing, also called bundle dyeing, transfers the shape and color of leaves straight onto cloth. Leaves are laid on fabric, rolled up tight, and steamed or simmered, and the pigments and tannins in each leaf print where it touched. Mimosa hostilis root bark earns its place in the process as the background: it turns the whole scarf a dusky rose or plum, so the leaf prints sit on a colored ground instead of bare white.
Dissolve the alum in hot water, add it to a pot of warm water, and soak the wetted silk in it for an hour or more, keeping it below a simmer. Silk marks easily, so do not boil it. Rinse lightly and leave it damp. Mordanting wool before a bark bath uses the same alum percentage.
For a single scarf, a few tablespoons of powder or a small handful of shredded bark is plenty. Soak it in warm water, bring it to a gentle simmer for 30 to 45 minutes, and strain it well through fine cloth; loose particles of powder will speckle the print. Keep the bath neutral to slightly acidic if you want rose and plum rather than brown. Filtering a bark bath without losing the colour shows how.
There are two ways to use the bath, and they give different looks:
Spread the damp silk flat and arrange the leaves on half of it, veins down, then fold the other half over (or lay the blanket on top). Roll the whole stack around the dowel as tightly as you can, and bind it hard with string every inch or so. Pressure is what makes a sharp print; a loose bundle gives blurred shapes.
Steam the bundle for 60 to 90 minutes, turning it once, or simmer it gently in the leftover bark bath for the same time. Then leave it to cool, and if you have patience, leave it wrapped for one to three days. The prints deepen as it rests.
Unwrap the bundle, shake off the leaves and hang the silk to dry out of the sun. Leave it a week before washing it for the first time, then wash by hand in cool water with a pH-neutral wool wash.
Leaf prints darken dramatically with iron. Dip the blanket in a weak iron solution before rolling, or brush a little onto the leaves, and oak and eucalyptus in particular print near-black on the bark-colored ground. Use iron sparingly on silk, which it can weaken; iron as a modifier, and how far to go explains how little is enough.
| Problem | Likely cause | Fix |
|---|---|---|
| Speckles on the silk | Powder particles in the bath | Strain through finer cloth, or use shredded bark |
| Blurred leaf shapes | Bundle too loose | Roll tighter and tie every inch |
| Brown ground instead of rose | Alkaline water or too much heat | Keep the bath below a simmer and slightly acidic |
| Faint prints | Leaves too dry, or silk not mordanted | Soak leaves first; mordant with alum |
Overdyeing is dyeing one color on top of another. Mimosa hostilis gives rose to plum, so over indigo blue it makes violet and deep purple, over a yellow dye it makes peach, coral and rust, and with iron it turns grey and slate. Dye small samples first, and change only one thing between them.
Sassafras root bark gives warm tan, rose-tan and orange-brown on wool mordanted with alum, and grey-brown with an iron afterbath. Use about a pound of bark to a pound of dry wool. Soak the bark overnight, simmer it gently for an hour, strain, then hold the mordanted wool in the bath just under a simmer for an hour and let it cool there.
Hard water carries calcium and magnesium and usually runs alkaline, and both shift a tannin dye. With Mimosa hostilis the purples drift toward brown and the color looks duller. Iron in well water greys it further. Rainwater or distilled water is the simplest answer; a little white vinegar or citric acid, to bring the bath to about pH 5 or 6, is the next best.
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