---
title: "Mordant"
description: "A mordant is a substance, usually a metal salt such as alum, that fixes a dye to fibre and can change its colour."
type: Glossary
url: https://teazle.art/glossary/mordant
published: 2026-10-14
updated: 2026-10-14
author: "The Teazle editors"
---

# Mordant

*A mordant is a substance, usually a metal salt such as alum, that fixes a dye to fibre and can change its colour.*

Many natural dyes will not bond to fibre on their own. A mordant, from the French *mordre*, to bite, is applied before or with the dye to make the colour fast. Alum is the classic mordant; iron, tin and copper salts darken or brighten colours.

## Why does it matter for printed textiles?

Printers learned to print the mordant rather than the dye: when the cloth was dyed in [madder](https://teazle.art/glossary/madder.md), only the mordanted areas took colour, and different mordants gave different shades from a single dye bath. This was the basis of Indian [chintz](https://teazle.art/glossary/chintz.md).


## Sources

1. [Mordant (AAT 300015299)](http://vocab.getty.edu/page/aat/300015299). Getty Art & Architecture Thesaurus
2. [Mordant (Q5857145)](https://www.wikidata.org/wiki/Q5857145). Wikidata

Canonical: https://teazle.art/glossary/mordant