Enter the dry weight of the fabric, yarn or leather you want to dye and choose how deep you want the colour. The calculator tells you how much Mimosa hostilis root bark to weigh out, plus the alum and water to go with it.
Planning soap, a wood stain or a balm instead? The project planner covers those and gives you printable instructions.
How the calculator works
Natural dyers measure dye against the dry weight of the material being dyed, known as weight of fibre (WOF). A recipe at 50% WOF uses 50 g of dyestuff for every 100 g of fibre. The sum is always the same: fibre weight multiplied by the percentage gives the weight of bark.
Weigh your material before you wet it. Wet fibre weighs far more and will throw the numbers off.
Choosing a strength
| Shade | % of fibre | Per 100 g |
|---|---|---|
| Pale | 25% | 25 g |
| Medium | 50% | 50 g |
| Deep | 100% | 100 g |
These are starting points, not fixed rules. Root bark is a natural material and each fibre takes colour differently, so dye a small sample before you commit a full batch. If the sample is too light, raise the percentage or leave the fibre in the bath for longer. You can type any percentage into the calculator.
Mordant and water
Alum is the mordant most dyers reach for with wool and silk, usually at 10 to 15% of the fibre weight. Cotton, linen and other plant fibres are normally prepared differently, so follow the instructions from your mordant supplier for those. For the dye bath, about 3 litres of water for every 100 g of fibre lets the material move freely and take colour evenly.
Which form of bark to use
The weight is the same whichever form you buy. Powder releases colour fastest, shredded bark strains out cleanly, and whole bark keeps longest in storage and can be broken up as you need it.
Common questions
How much Mimosa hostilis root bark do I need to dye 1 lb of wool?
One pound is about 454 g. At a medium strength of 50% you need about 227 g of bark, or 8 oz. For a deep shade at 100% you need the full 454 g.
Can I reuse the dye bath?
Often, yes. A bath that has given a deep shade usually has colour left in it, and a second batch of fibre will come out paler. Dyers call this an exhaust bath.
Do I measure powder and whole bark the same way?
Yes. Go by weight, not by volume. A cup of powder weighs much more than a cup of loose bark pieces.
Does the calculator work for soap making?
No. It is built for dyeing fibre. For soap, see our guides for dyers and soap makers.
The bark we sell is a raw material for natural dyeing, soap making and cosmetic formulation. It is not sold for human consumption.