Natural dyers measure everything against the dry weight of what they are dyeing, called the weight of fibre. Enter that weight below and the calculator works out how much Mimosa hostilis root bark you need, plus the alum and iron amounts if you use them.
- Alum mordant (optional, 12 to 20% of fibre weight)30 to 50 g
- Iron to darken the colour (optional, about 2%)5 g
- Smallest bag that covers it500 g
How the calculator works
It uses the same ratios as our fabric dyeing guide:
- Deep shade: the same weight of bark as dry fibre.
- Light shade: half the weight of the fibre.
- Alum: 12 to 20 percent of the fibre weight. It matters most on cotton and linen.
- Iron: about 2 percent of the fibre weight, only if you want a darker, greyer colour.
These are starting points. Water, fibre and bark all vary, so dye a small sample before a full batch.
Quick reference
| What you are dyeing | Dry weight (about) | Bark, deep shade | Bark, light shade |
|---|---|---|---|
| One skein of yarn | 100 g | 100 g | 50 g |
| One cotton T-shirt | 150 g | 150 g | 75 g |
| A metre of medium-weight fabric | 250 g | 250 g | 125 g |
| One pound of fibre | 454 g | 454 g | 227 g |
| A small production batch | 1 kg | 1 kg | 500 g |
Common questions
How do I find the weight of fibre?
Weigh the fabric or yarn dry, before you wash or wet it. A kitchen scale is accurate enough.
How much Mimosa hostilis root bark do I need to dye one pound of fabric?
About one pound (454 g) of bark for a deep shade, or half a pound (227 g) for a light one.
Can I use less bark and simmer it longer?
A longer simmer and an overnight soak help, but they do not replace bark. For strong colour, use the full amount, then reuse the bark for a second, lighter bath.
Does the form of bark change the amount?
No. Whole, shredded and powdered bark are the same material, so the weight is the same. Powder only releases its colour faster.
What about soap, balm or wood?
The project planner covers soap, infused oil, balm and wood, with instructions you can download.
Dyeing in volume?
Orders from 5 kg are priced at a lower rate per kilogram on our wholesale page.
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