How to Dye Fabric with Mimosa Hostilis Root Bark

What You'll Need

• 50–100g Mimosa Hostilis root bark (shredded or chips) per 100g dry fabric weight
• A large stainless steel or enamel pot — avoid aluminum or iron pots, which shift the color
• Alum mordant (potassium alum — available at craft and homebrewing shops)
• Mesh strainer or cheesecloth
• Pre-washed natural fiber fabric: cotton, linen, wool, or silk
• Wooden spoon or tongs for stirring
• A dedicated dye pot — don't use it for food after dyeing

Step 1 — Mordanting Your Fabric

Mordanting is the most important step most beginners skip, and skipping it is exactly why their dye washes out. A mordant is a metallic salt that bonds to both the fiber and the dye molecule, locking color in permanently. For Mimosa Hostilis, alum gives the truest, brightest results.

Dissolve alum in hot water using roughly 15–20% of the dry weight of your fabric. If you're dyeing 100g of fabric, use 15–20g of alum. Submerge your pre-wet fabric and hold at a gentle simmer for 45–60 minutes. Remove, gently squeeze out excess liquid, and you're ready to dye. You can proceed immediately or wrap the wet mordanted fabric in plastic and refrigerate it for up to 48 hours.

Step 2 — Preparing the Dye Bath

Place your Mimosa Hostilis root bark in a large pot and cover with cold water. Let it soak for 8–12 hours (overnight is ideal). This softens the bark and begins drawing out the natural colorants — you'll notice the water turning a deep reddish-brown almost immediately.

After soaking, bring the pot to a gentle simmer — not a full rolling boil. High heat can dull the color and break down some of the pigment compounds. Hold the simmer for 1–2 hours, stirring occasionally, until the liquid deepens to a rich dark burgundy. For chips specifically, add an extra 30 minutes of simmering time.

Strain out all the bark material through your mesh strainer or cheesecloth. What remains is your dye bath — a beautiful, concentrated liquid ready for use. The spent bark can be composted.

Step 3 — Dyeing the Fabric

Bring your strained dye bath back to a gentle simmer and add your mordanted fabric. Keep the temperature steady — around 160–180°F / 70–80°C for most fibers. Move the fabric gently and frequently so the dye reaches every part of the cloth.

Dye for 45–90 minutes, depending on how saturated you want the color. Longer time in the bath generally means deeper, richer color. Remove the pot from heat and let the fabric cool slowly in the dye bath — this continued contact as it cools adds extra depth.

Rinse thoroughly in warm water, gradually moving to cooler water. Wash with a small amount of gentle detergent, rinse again, and hang to dry out of direct sunlight.

Color Results by Fiber Type

Tips for Best Results

• Water quality: Hard water can shift colors toward brown. If your tap water is very hard, try distilled or filtered water for the dye bath.
• pH modifiers: Adding a small amount of baking soda shifts color toward blue-purple. Adding a splash of white vinegar shifts toward warmer red-burgundy.
• Iron modifier: A brief dip in an iron water solution (rusty nails steeped in water) after dyeing saddens the color to deep gray-purples and slate tones.
• Light fastness: Store and display naturally dyed textiles away from direct sunlight to preserve color vibrancy over time.
• Washfastness: Always wash naturally dyed textiles in cold or cool water. Use a small amount of gentle, pH-neutral detergent. With proper mordanting, Mimosa Hostilis dyed wool and silk are surprisingly wash-fast.