Mimosa Hostilis Root Bark Powder
Botanical use only
$37.501/4 lb
One bath, start to finish: scour the fibre, mordant it with alum at twelve per cent of its dry weight, soak the bark overnight, hold the pot at eighty degrees for an hour, and let it cool with the fibre in it. Everything else in this section is a variation on those five steps.
Editorial desk · Written and checked in house · Updated
This is the whole process in one place, in the order you will actually do it. Each step links to the article that goes deeper, so you can follow this page for a first bath and come back for the detail afterwards.
| What | Figure | Of what |
| --- | --- | --- |
| Alum | 10 to 15% | Dry weight of the fibre |
| Bark | 50 to 100% | Dry weight of the fibre |
| Temperature | 80°C / 175°F | Never a boil |
| Time at temperature | About 1 hour | Then cool in the pot |
Weigh the fibre dry, before it is wetted. Wet wool holds several times its weight in water, and a damp weighing makes both percentages wrong at once.
Wash the fibre in hot water with a pH-neutral detergent to take off spinning oil, lanolin and sizing, then rinse and keep it wet. Colour cannot reach fibre that water cannot wet, and most patchy results people blame on the bark start here.
Dissolve alum at about twelve per cent of the dry fibre weight in a jug of very hot water until the water is clear, stir it into the pot, then add the wet fibre. Raise the heat slowly to just under a simmer, hold for an hour, turn it off and let it cool in the pot — overnight if you can.
The one thing to get right is that the alum is fully dissolved before the fibre goes in. An undissolved crystal mordants the spot it rests against far more heavily than everything around it, and the bath afterwards shows it as a hard-edged pale patch. Full method in mordanting wool before a bark bath.
Weigh the bark against the same dry fibre weight — half for a mid shade, the full weight for a deep one — put it in a mesh bag, cover it with cool water and leave it overnight. See how much bark per pound of fibre and cold soak or straight to heat.
The next day bring the pot up slowly to about 80°C and hold it there for an hour. Then lift the bag out, or strain, before any fibre goes near it — loose material against wool leaves specks that will not rinse out of the plies. See filtering a bark bath.
Enter the wet, mordanted fibre into the strained bath, bring it back to temperature gently, and hold it for forty-five minutes to an hour. Turn the fibre once or twice; do not stir it. Wool at temperature plus agitation is how felting starts.
Then turn the heat off and leave the fibre in the pot to cool. The colour keeps going in as the bath falls, and an overnight cool is the cheapest depth available.
Do not let it boil. This is the one fault that cannot be corrected: a rolling boil takes the purple to brown in minutes and no amount of cooling brings it back. See keeping a bark bath purple.
Rinse in water of roughly the same temperature as the fibre — sudden changes felt wool — until it runs clear, wash once with a pH-neutral detergent, rinse again, and dry out of direct sun. Judge the colour dry: wet fibre reads one to two shades darker than it will end up.
Changing two things at once teaches nothing about which one moved the colour. See the eight faults that spoil a first bath.
Fibre and its dry weight, alum percentage, bark weight and cut, temperature, time, water, and the batch code on the bag. Bark from different harvests differs and so does tap water, so the notebook is the only way a shade you liked comes back. It is also what makes a fastness test worth running.
Gloves, and a fitted mask when weighing or milling powder — see working safely with fine milled bark. Dedicated pots and spoons, never used for food afterwards. Spent bark goes on the compost; keep iron and mordant baths out of the food area and dispose of them per local guidance.
A raw botanical material for dyeing, soap making and craft work. It is not food, it is not a supplement, and it is not for human consumption.
Part of our guide: Mimosa Hostilis Root Bark: A Dyer's Handbook
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.
Your cart is empty
Everything we sell is batch-tested, and we tell you what ships to your state before you add it.
Browse the shop
