Mimosa Hostilis Root Bark Powder

What you get

Mimosa hostilis root bark, milled to a fine, even powder. It is the same bark as our shredded and whole cuts, taken all the way down to a powder, and in the bag it reads mauve to red-brown depending on the light.

The plant is Mimosa tenuiflora, still sold under its older name Mimosa hostilis, a thorny tree of the legume family native to northeastern Brazil and southern Mexico. In Brazil it is called jurema preta. The root bark is the part dyers want: it is dense with tannins and with the red-purple pigments that make it one of the few natural dyes that goes straight from bag to pot without a separate mordant for most wool work.

Why choose the powder over shredded bark?

Speed and concentration. A powder has far more surface in contact with the water than a strand of bark, so it gives up its color in a fraction of the simmer time. That makes it the cut for small, controlled jobs: test skeins, dye samples, a single scarf, and soap, where you want color in the oil rather than a pot to strain. Why particle size changes everything in a dye pot goes into the trade-off in detail.

The price of that speed is straining. Powder stays suspended, so a powder bath has to be settled and poured off or run through fine cloth before the fiber goes in, or specks will lodge in the wool. If you are dyeing a full fleece or several pounds of yarn, the shredded cut is easier to lift out and gives more than one bath. The three cuts of Mimosa root bark, and who each one suits compares all three side by side.

What colors does Mimosa hostilis powder give?

On wool and silk, a first bath gives dusky pinks, plum and a warm red-brown; more bark and a longer simmer push it toward burgundy and a deep chocolate. A little alum in the fiber first brightens the pinks. An iron afterbath turns the same bath slate, charcoal or near-black, which is one of the reasons dyers keep a pound of this on the shelf: one material, two very different palettes. Iron as a modifier, and how far to go shows how quickly that shift happens.

The pot's pH moves the color as well. Keep the bath neutral to slightly acidic if you want to stay in the purples, and expect browns if it drifts alkaline. Keeping a bark bath purple instead of brown is the short version of how to hold it there.

Cotton and linen take the color more palely than wool and silk, because plant fibers have no protein for the tannins to bind to. Mordanting them with tannin and then alum first closes most of that gap; wool, silk, cotton and linen in the same bath shows the difference on one set of swatches.

How much powder do you need per pound of fiber?

Dyers measure bark against the dry weight of the fiber, written as a percentage "of weight of fiber" (WOF). A pale tint takes about 25 to 40 percent, 4 to 6 ounces for a pound of wool; a mid shade about 50 to 75 percent, 8 to 12 ounces; and the deepest plums up to an equal weight of bark and fiber. Powder gives up its color most completely, so start at the lower end of each range.

That makes a quarter pound enough to learn on with a few test skeins, and a full pound enough for one to two pounds of fiber in mid shades. How much bark per pound of fibre has the full table, and testing a dye before you commit a fleece is worth ten minutes before the first big pot.

Using it in cold-process soap

Soap makers use the powder for color alone: it gives bars in tones from warm tan to dusky brown-purple depending on how much goes in and how it is added. The usual routes are infusing the powder in part of the recipe's oil and straining it, or adding a small amount at light trace. Start low, since the color deepens as the bar ages over the following weeks. Bark as a colourant in cold process soap walks through both methods.

We make no claim about what the bark does for skin; it is sold here as a colorant.

Sizes, price and bulk

Sold by weight at one price per pound, in four sizes: 1/4 lb, 1/3 lb, 1/2 lb and 1 lb. The size you pick sets the price shown in the buy box, and that is the price you are quoted. Orders of parcel items from 100 dollars ship free.

Buying for a studio, a class or a soap line? Several pounds at a time are priced individually on the bulk and wholesale page, and a person replies with a quote.

Ordering and delivery

You place your order, a person checks it, and payment details arrive in your order chat and by email; once payment is confirmed, the order is weighed, sealed and shipped from California with tracking. We ship to addresses in the United States only. The shipping policy has the details. Every order is packed in a double-sealed, smell-proof bag that is flushed with nitrogen before it is closed: the nitrogen pushes the oxygen out, so the bark does not oxidize in transit or on your shelf and arrives as fresh as the day it was packed.

Powder keeps well if it stays dry and dark. Reseal the bag after each use, keep it out of a steamy kitchen, and it will still be strong a year from now. See storing root bark so it lasts.

Handling fine powder

Fine bark powder lifts into the air when it is poured, so weigh it out away from drafts, wear a dust mask and gloves, and keep it away from food, children and pets. Working safely with fine milled bark covers the sensible basics.

This is raw botanical material for dyeing and craft. It is not food, not a supplement and not for human consumption.