4 Natural Dyes That Don't Need a Mordant

Most natural dyes need a mordant to give lasting color, but some do not. These substantive dyes bond to the fiber on their own, usually because they are rich in tannin. Dyeing with them is quicker and simpler, because you can skip the mordanting step. Here are four natural dyes that don't need a mordant.

Why don't some dyes need a mordant?

A mordant, usually alum, works as a bridge between the dye and the fiber. Tannins can bind directly to fibers, so tannin-rich dyes such as walnut, oak gall and pomegranate fix themselves. Indigo works in a different way: it is dissolved in a vat and becomes insoluble again inside the fiber as it meets the air. To learn more about mordants, read our guide to mordants for natural dyeing.

1. Indigo

Indigo is one of the oldest dyes in the world and the source of every natural blue, from pale sky to deep navy. Most natural indigo comes from the leaves of Indigofera tinctoria, native to South Asia. Indigo does not need a mordant, but it does need a vat: a bath in which the indigo is reduced so it can dissolve. Learn how in our indigo vat guide.

2. Black walnut hulls

Black walnut hull powder is so rich in tannin that anyone who has handled fresh walnuts knows how long the stain stays on their hands. Walnut gives warm, earthy browns on all natural fibers without a mordant. It has also long been used for ink and wood stain. For darker browns and near-blacks, add an alum mordant or a short iron afterbath.

3. Oak galls

Oak galls contain more tannin than almost any other plant material. On their own they give soft beiges, and with iron they give grays and blacks, the basis of traditional iron gall ink. They are also the classic tannin for preparing cotton and linen for other dyes, and are popular in eco printing. Read our oak gall tannin guide.

4. Pomegranate peel

Pomegranate peel powder is rich in tannin and gives golden yellows, beiges and tans without a mordant. With iron it shifts to khaki and olive green. Like oak gall, it can also be used as a tannin before alum on cotton and linen.

Another well-known tannin dye is quebracho, from a South American tree, which gives golden browns and brownish reds.

Can you dye fabric without a mordant?

Yes, with the dyes above. Keep in mind that a mordant often still helps: adding alum usually makes tannin colors brighter and more lightfast, and iron gives darker shades. Most other dyes, such as madder and weld, do need a mordant, or the color will wash out and fade.

Frequently asked questions

Which natural dye is the easiest without a mordant?

Black walnut. Simply soak or heat the fabric in the dye bath for warm browns.

Do no-mordant dyes work on cotton?

Yes. Tannin dyes bind well to cotton and linen, and indigo works on all natural fibers.

Is indigo colorfast without a mordant?

Yes, indigo has very good wash and light fastness. Some color may rub off at first, so wash new indigo pieces separately.

Related: Shop natural tannins · Natural brown and black dyes · Natural dyes: complete guide