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The Art of Fixing Colors: A Guide to MORDANTS in Natural Dyeing

In this blog post, we explored the significance of mordants in the art of natural dyeing, highlighting their role as essential agents that fix and set plant-based pigments to textiles, ensuring vibrant and long-lasting colours. 🌿

three glass bottles with mordant inside, aluminium acetate
mordants for natural dyes


If you've ever ventured into the world of natural dyeing, you've likely encountered the term "mordant." But what exactly is a mordant, and why is it a crucial ingredient in the art of botanical colour creation?

What is a Mordant?

In the realm of natural dyeing, a mordant is like the overlooked hero, quietly playing a vital role behind the scenes. Essentially, a mordant is a substance that helps fix or set natural dyes to the fabric or fibre. It acts as a bridge between the plant-based pigments and the textile, ensuring that the colours not only adhere but also remain vibrant and long-lasting.

Different Types of Mordants

There are various types of mordants used in natural dyeing, each with its unique characteristics and effects on colour.

Common mordants include

  • Alum, like potassium alum or aluminium acetate.

  • Iron, like ferrous sulphate

  • copper

  • and tannin-rich substances like oak galls or sumac leaves.

Alum, for instance, is prized for its ability to produce bright, clear colours, while iron can darken and modify hues, offering a range of greys and blacks.

a hand lifting a degrade yellow cotton fabric dyed on a pot
Fabric dyed with onion skins using aluminium acetate

Why Do We Use Them?

The use of mordants serves a twofold purpose. Firstly, they enhance the colourfastness of natural dyes, ensuring that the colours do not fade quickly when exposed to light, washing, or time.

Secondly, mordants can also alter and shift the colour palette, allowing dyers to achieve a broader spectrum of shades and tones. This flexibility is particularly valuable for achieving the desired colour outcome in natural dyeing projects.

Safety Measures When Using Mordants

While mordants are essential tools in the natural dyer's kit, it's crucial to exercise caution when working with them.

Many mordants can be toxic if mishandled or ingested ( for example copper can be very toxic, this is why I don't use it in my studio).

Always wear protective gear like gloves and a mask when handling mordants in their powdered form, and work in a well-ventilated area to minimize exposure to fumes. Additionally, ensure proper storage of mordants, keeping them out of reach of children and pets.

In conclusion, mordants are the unsung heroes of the natural dyeing world, enhancing the beauty and longevity of botanical colours.

By understanding the different types of mordants and practising safety measures when using them, you can embark on your natural dyeing journey with confidence, creating stunning, eco-friendly textiles that stand the test of time.

Happy botanical dyeing! 🌿🌈


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