Linen fabric dyed with black walnut hull in light to dark brown

Black Walnut Dye Guide: Browns to Near-Black from Walnut Hulls

October 21, 2026

Black walnut is one of the easiest natural dyes to start with. The hulls are rich in tannin and in a brown colorant called juglone. Together they give warm tans, chocolate browns and, with iron, deep grey-browns that come close to black. You do not need a mordant. This guide shows you how much walnut to use, how alum and iron change the color, and how to work with walnut safely.

What is black walnut dye?

Black walnut dye comes from the green-to-black outer hulls of the black walnut, Juglans nigra. The hulls are dried and ground into powder. Ours are collected in Turkey and shade-dried. Our black walnut hull powder is ready to use, with no crushing or long soaking.

The hulls contain two kinds of color makers:

Juglone, a naphthoquinone. It binds to skin and fiber and darkens as it oxidizes. It is the same compound that stains your hands brown when you hull walnuts.
Tannins, which bond to fiber on their own and turn dark grey-brown with iron.

Because of these compounds, walnut is a substantive dye. It colors fiber without a mordant. That is why it appears in our list of natural dyes that don't need a mordant.

How much black walnut powder to use

Expert sources give a wide range for walnut, from about 25% to 100% WOF. The color depends on how much you use and how long you steep.

Shade	Walnut hull powder (% WOF)	Notes
Light beige and tan	10–25%	Short dye time, or an exhaust bath
Medium warm brown	30–50%	Start at 30%
Deep chocolate	75–100%	Long steep, cool overnight in the bath

Start at 30% WOF. For 100 g of dry fiber, that is 30 g of powder. Use our natural dye calculator to scale up.

Tip: Walnut builds color with time. A long steep, or leaving the fiber in the bath overnight, gives a darker brown without using more powder.

Before you start: fiber and mordant choices

Scour your fiber first so the dye takes evenly. See how to prepare fiber for natural dyeing.

Wool and silk

Wool and silk take walnut very well with no mordant. You get warm, rich browns. Alum is optional. In a 2013 university study of walnut dyes, alum made the browns on wool warmer and brighter, and it improved lightfastness. Without alum, the brown was cooler and duller.

If you want that warmer brown, mordant with alum at 10–15% WOF, plus cream of tartar at 6–7% WOF for wool. See mordanting wool and silk.

Cotton and linen

Cotton and linen take walnut less well. Without any mordant, the result is often a light tan that can fade. For stronger, longer-lasting browns on plant fibers, use the walnut itself as your tannin step:

Simmer walnut powder at 25–50% WOF for 1 hour. Add the wet fabric and let it steep for 1 hour or overnight.
Without rinsing, mordant in alum at 12–15% WOF with soda ash at about 1.5–2% WOF.
Rinse, then dye in a fresh walnut bath or go straight to iron for grey-brown.

Our guide to mordanting cotton and linen has the full tannin-and-alum method.

Recipe 1: Warm brown with no mordant

For 100 g of dry wool, silk, or tannin-treated cotton.

Make a paste. Mix 30–50 g of walnut hull powder with a little warm water until smooth.
Extract the color. Add the paste to 3–4 litres (about 1 US gallon) of water. Simmer gently for 1–2 hours.
Rest the bath. For darker brown, let the bath cool overnight before you dye.
Strain. Pour through a fine cloth to remove the powder. This prevents dark specks.
Add the fiber. Add wet fiber to the warm bath.
Heat. Bring to 80–90 °C (176–194 °F). Hold for 1 hour. Stir gently.
Cool in the bath. Leave the fiber to cool, or overnight for deeper color.
Rinse and wash. Rinse until the water runs clear. Wash with a pH-neutral soap.

Tip: Wool felts easily. Heat and cool slowly, and never move wool from hot to cold water.

Tip: The bath is rarely exhausted after one use. Dye more fiber in it for beige and tan.

Recipe 2: Dark grey-brown to near-black with iron

Iron reacts with walnut tannins. Browns turn into cool grey-browns, dark taupe and, on cotton and linen, near-black. Use iron (ferrous sulfate) as an afterbath.

Dye a deep brown base with Recipe 1. Use 75–100% WOF walnut for the darkest results.
Dissolve iron in hot water in a separate jar. Use 0.5–1% WOF for wool and silk. Use 1–2% WOF for cotton and linen.
Add the iron solution to a pot of warm water and stir well.
Add the wet fiber and keep it moving. Watch it darken within minutes.
Remove it when you like the shade, usually after 10–30 minutes. Rinse well.

For the darkest near-black on cotton or linen, repeat the cycle: walnut bath, rinse, iron dip, rinse. Two or three layers give deeper color than one dip in strong iron, and they are kinder to the fiber.

Tip: Never go above 1% WOF iron on wool or silk. Iron makes protein fibers harsh and brittle. Read our iron mordant guide for more.

Recipe 3: Color variations

Mahogany: Overdye walnut brown in a light madder bath. Walnut and madder is a classic historical pair. Try madder root powder.
Deep navy-brown: Dip walnut-dyed cotton into a medium indigo vat. Walnut plus iron plus indigo gives a very dark blue.
Golden brown: Use alum-mordanted wool. The alum warms the brown toward gold.

For more brown and purple ideas, see how to get purple and brown shades from plant dyes.

Safety: handling walnut and juglone

Walnut hull powder is safe to use with simple care. Juglone irritates skin and leaves a brown stain that can last for weeks.

Wear gloves. Use rubber or nitrile gloves when you handle powder, dye liquid and wet fiber.
Wear a dust mask when you measure the powder. Fine plant dust can irritate your nose and lungs.
Use dedicated tools. Keep dye pots, spoons and buckets for dyeing only. Never use them for food.
Clean up quickly. Walnut stains counters, sinks and wood. Wipe spills right away.
Work with good air flow. Open a window or use a fan when you simmer the bath.
Wash your skin with soap and water if dye touches it.

Tip: People with nut allergies should take extra care and avoid skin contact with walnut materials.

Troubleshooting

Color is light or pinkish beige. You used too little walnut or dyed for too short a time. Use more powder, steep overnight, or cool the fiber in the bath.
Dark specks on the fiber. Undissolved powder stuck to the fiber. Strain the bath through fine cloth before dyeing.
Cotton came out pale. Cotton has low affinity for walnut. Use walnut as a tannin step, then alum, then dye again or use iron.
Streaky or patchy grey after iron. The fiber was not moving or the iron was not fully dissolved. Dissolve iron in hot water first and stir constantly.
Wool feels rough after iron. Too much iron or too much heat. Stay at or below 1% WOF and keep the iron bath warm, not hot.
Brown faded in the sun. Try an alum mordant on wool. It improved walnut lightfastness on wool in testing.

Frequently asked questions

Does black walnut dye need a mordant?

No. Black walnut is a substantive dye because of its tannins and juglone. It colors wool and silk without a mordant. Alum is optional and gives a warmer brown. Cotton and linen give better results with a tannin and alum mordant.

How much black walnut powder do I need?

Use 30–50% WOF for medium brown and 75–100% WOF for deep chocolate. Start at 30%, which is 30 g of powder for 100 g of dry fiber.

How do I get black from walnut?

Dye a deep brown base with 75–100% WOF walnut, then use an iron afterbath. On cotton and linen, repeat walnut and iron layers for near-black. Pure jet black usually needs extra tannin or an indigo overdye.

Is black walnut dye safe?

Yes, with care. Juglone in the hulls irritates and stains skin. Wear gloves, use a dust mask when measuring powder, and keep dye tools away from food.

Does walnut dye work on cotton?

It works, but cotton takes walnut less well than wool. Without a mordant you get light tan. Use walnut as the tannin step, then alum, then dye again or use iron for stronger color.

Sources and further reading

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