How to Dye Yarn Black with Iris Roots and Chocolate Mint

Materials & tools you'll need

Step 1 — Prepare the iris root and chocolate mint dye bath

Collect discarded iris roots left over from propagating your iris plants, and wash them thoroughly under running water to remove any soil. Chop the cleaned roots into manageable pieces so they release their pigment more readily. Fill a large pot with pH-neutral water, around pH 7 — checking with pH test strips if you have them on hand — and add the chopped iris roots along with your dried chocolate mint. Simmer the mixture on medium heat for about an hour or two, until all of the pigment appears to have been drawn out of the roots and into the water.

Step 2 — Scour the wool

While the dye bath simmers, scour your two-ply pure wool yarn to remove any oils or residue that could stop it from taking dye evenly. Tie the yarn up to keep it from tangling, then add it to a pot filled with water and soap. Simmer on the stove for about half an hour, or until the water looks slightly cloudy — a sign the oils have lifted out of the fibres. Rinse the scoured wool thoroughly under cold running water, then squeeze out the excess water without wringing it, which can felt or distort the yarn.

Step 3 — Prepare the two mordants

This project uses two separate mordants side by side so you can compare their effects: a homemade iron water solution, and a mixture of cream of tartar and food-grade alum powder dissolved in water. Prepare both mordant solutions in separate pots, then heat each one on medium heat for about an hour to fully activate it. Wear protective gloves and a mask throughout this step, and work in a well-ventilated area, since both food-grade alum and the iron mordant solution require careful handling.

Step 4 — Dye the wool

Once your iris root and chocolate mint dye bath and both mordants are ready, divide your scoured wool in half. Dip one half into the iron water mordant solution, and dip the other half into the alum and cream of tartar mixture, so you can see how each mordant shifts the final colour. Transfer the mordanted wool into the iris root and chocolate mint dye bath and let it soak for several hours, checking periodically until you reach your desired depth of black. Rinse the dyed wool thoroughly under cold running water, then squeeze out the excess water without wringing it.

Step 5 — Finish and dry

If you're also working with acid dyes anywhere in your process, follow the manufacturer's instructions for washing out any excess dye before drying. Lay the dyed yarn out flat, rather than hanging it, to avoid stretching or distorting the fibres, and let it air dry completely before handling or skeining it. Once fully dry, your black yarn — dyed naturally with iris roots and chocolate mint — is ready for your next crochet or knitting project.

Frequently asked questions

What do I need for this black yarn dyeing project?
You'll need discarded iris roots, dried chocolate mint, two-ply 100% pure wool yarn (such as Briggs and Little Regal Wool in Washed White), a scouring agent like soap, protective gloves and a mask, a large pot with a lid, measuring cups and spoons, pH test strips, food-grade alum, and a homemade iron mordant solution made from vinegar, water, and rusty items.

What safety precautions should I take when working on this project?
Wear protective gloves and a mask, and work in a well-ventilated area when handling mordants like food-grade alum or the iron mordant solution. If you use a microwave anywhere in your dyeing process, make sure the setting is safe for that purpose.

How long does each step take to complete in this project?
Simmering the iris roots to extract pigment takes about one to two hours. Scouring the wool takes about half an hour. Heating the mordants takes about an hour, and soaking the wool in the dye bath to reach your desired darkness can take several more hours.

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