Dye Material Needed
100 g
Mordant
15 g
Water
3.3 L
Colorfastness
Moderate
15 g
3.3 L
Orange, rust, brown
Moderate
Inputs
Result
At 100% WOF for medium onion skin, you need dye equal to the fiber weight. Alum at 15% WOF = 100 × 0.15 × 1.0 (cotton multiplier) = 15 g. Water = 100 / 30 = 3.3 L.
Inputs
Result
Indigo at dark depth = 30% WOF. 200 g × 0.30 = 60 g of indigo powder. No mordant needed as indigo bonds through a vat reduction process. Water = 200 / 30 = 6.7 L.
Inputs
Result
Madder at light depth = 25% WOF. 50 g × 0.25 = 12.5 g madder root. Alum at 15% WOF with silk’s 0.7× multiplier = 50 × 0.15 × 0.7 = 5.25 g (rounded to 5.3 g). Water = 50 / 30 = 1.7 L.
Natural dye amounts are calculated as a percentage of the weight of fiber (WOF). Most plant dyes need 50–200% WOF for medium shades, while concentrated extracts like indigo need only 5–30% WOF. The exact ratio depends on your dye source and desired color depth.
| Dye Source | Light WOF% | Medium WOF% | Dark WOF% | Colorfastness |
|---|---|---|---|---|
| Onion Skin | 50% | 100% | 200% | Moderate |
| Indigo | 5% | 15% | 30% | Excellent |
| Madder Root | 25% | 50% | 100% | Excellent |
| Avocado | 100% | 200% | 400% | Good |
Alum (aluminum potassium sulfate) at 15% WOF is the safest and most common mordant for beginners. It produces the truest colors without shifting hues. Iron darkens colors at just 2% WOF, while copper shifts colors toward green at 3% WOF.
| Mordant | WOF% | Color Effect | Best For |
|---|---|---|---|
| Alum | 15% | Brightest, truest | All fibers, beginners |
| Iron | 2% | Darker, grayed | Deep earth tones |
| Copper | 3% | Green shift | Blue-green tones |
| None | 0% | Lighter, fugitive | Walnut, indigo (self-mordant) |
Indigo and madder root are the most colorfast natural dyes, rated excellent for wash and light fastness. Both have been used for centuries in textiles worldwide. Walnut and logwood are rated good. Turmeric, despite producing vibrant yellow, has poor colorfastness and fades quickly.
| Dye Source | Color | Colorfastness | Wash Resistant |
|---|---|---|---|
| Indigo | Blue/navy | Excellent | Yes |
| Madder Root | Red/coral | Excellent | Yes |
| Black Walnut | Brown/tan | Good | Yes |
| Turmeric | Yellow | Poor | No |
Protein fibers like wool and silk absorb dye more readily than cellulose fibers like cotton and linen. Wool needs about 20% less mordant and achieves richer color depth. Cotton requires a tannin pre-treatment or extra mordant for comparable results.
| Fiber | Dye Absorption | Mordant Multiplier | Prep Needed |
|---|---|---|---|
| Wool | Excellent | 0.8× | Scour only |
| Silk | Excellent | 0.7× | Degum + scour |
| Cotton | Good | 1.0× | Scour + tannin optional |
| Linen | Moderate | 1.1× | Scour + tannin recommended |
Use approximately 30 grams of fiber per liter of water for the dye bath. The fiber should move freely in the pot without being tightly packed. For 100 g of fiber, you need about 3.3 liters. The mordant bath uses the same water ratio.
Read our guide
Read our guide
Read our guide
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Last Updated: Mar 16, 2026
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