Natural Dye Colors You Can Get from Mimosa Hostilis Root Bark
Most people discover Mimosa Hostilis root bark through its purples — and they're stunning. But the color range this bark can produce is significantly wider than the headline result. With different mordants, pH modifiers, and fiber types, you can pull everything from dusty rose and mauve all the way to charcoal gray, slate blue, warm tan, and deep burgundy-brown.
The Base Color Spectrum
When used with an alum mordant on wool — the most straightforward setup — Mimosa Hostilis root bark produces a range centered on purple, mauve, and burgundy. At lower concentrations (50g bark per 100g fiber), expect soft mauves and dusty lavenders. At higher concentrations (100g or more per 100g fiber), the color deepens into rich, saturated purples and burgundy-plum.
How Mordants Shift the Color
Alum (Potassium Alum) — Brightest, Truest Purple
The standard mordant for natural dyeing and the one that gives the clearest, brightest results. Colors range from dusty mauve at low concentrations to deep violet-purple at high ones. Alum doesn't shift the hue significantly — it simply optimizes and brightens whatever the dye bath naturally produces.
Iron (Ferrous Sulfate or Iron Water) — Gray-Slate, Charcoal-Purple
Iron "saddens" color — darkening and dulling it, shifting toward cooler, grayer results. Applied as a mordant or after-bath modifier, iron transforms Mimosa Hostilis purples into deep gray-slate, charcoal-purple, and near-black tones at high concentrations. Particularly striking on wool. Working ratio: As an afterbath modifier, dissolve ferrous sulfate at 2–4% of dry fiber weight. Dip for 5–10 minutes. At 2% you'll get charcoal-purple; at 4% results push toward near-black on wool.
Copper (Copper Sulfate) — Olive, Teal Undertones
Copper shifts the dye toward cooler, greener tones. With Mimosa Hostilis, copper mordanting can produce olive-mauve and dusty teal-gray results — a significant departure from the expected purple. Working ratio: Use copper sulfate at 2–3% of dry fiber weight. Handle with gloves and dispose responsibly.
No Mordant — Muted, Less Wash-Fast
You will get color without a mordant — Mimosa Hostilis is a high-tannin bark. But results will be noticeably softer and less saturated, and the color will fade more quickly. For any project you want to last, mordanting is worth the extra step.
pH Modifiers: Shifting the Hue After Dyeing
Alkaline — Baking Soda or Soda Ash → Blue-Violet
Adding a pinch of baking soda to the dye bath shifts Mimosa Hostilis color toward blue-violet and cooler purple tones. Use sparingly — too much can damage wool fibers.
Acidic — White Vinegar or Citric Acid → Red-Rose-Burgundy
Adding white vinegar or a small amount of citric acid shifts the dye toward warmer, redder tones — rose, burgundy, and warm mauve. A vinegar rinse after dyeing also helps set protein fiber colors.
Neutral Water → Truest Purple
Neutral pH water gives you the bark's natural color most accurately. If your tap water is hard, use filtered or distilled water for the cleanest, most repeatable baseline purple.
Color Results by Fiber Type
Wool
The most receptive fiber. Produces the deepest, most saturated colors — rich purples, deep mauves, and true burgundies. Wool's protein structure has a natural affinity for tannin-based dyes.
Silk
Results on silk are slightly lighter and more luminous than on wool — jewel-toned plums, dusty rose, and soft lavenders are common. The sheen of silk adds visual depth. pH modifiers work especially well on silk.
Cotton & Linen
Cellulose fibers require extra preparation. A tannin pre-treatment (soaking in oak gall, sumac, or black tea before mordanting) significantly improves uptake. With proper preparation, expect warm tawny-purples, muted mauves, and earthy burgundy-browns.
Tips for Consistent, Repeatable Color
- Weigh everything: Consistent results require consistent ratios. Weigh your dry fiber, your bark, your mordant, and your modifiers every time.
- Use the same water source: Mineral content in water affects color. If your tap water produces inconsistent results, switch to filtered or distilled water.
- Control temperature: A thermometer gives you repeatable control that "gentle simmer" alone doesn't.
- Keep a dye journal: Note your bark source, concentration, mordant, water source, temperature, timing, and fiber for every batch.
- Sample before committing: Dye a small sample skein or fabric swatch before putting your full project in the bath.
Questions about color?
Whether you're targeting a specific hue or exploring what's possible, get in touch and we'll point you in the right direction.