Unveiling the simplicity of learning how to make iron water for dyeing

In an increasingly fast-paced and synthetic world, the allure of natural dyeing has captured the imagination of many, drawing us closer to the beauty and magic that Nature has to offer. 

The art of natural dyeing, an ancient practice that dates back centuries, beckons us to rediscover the harmonious relationship between humans and our environment. And it’s a journey we’ve all been called to embark on!

While the world of natural dyeing may seem intricate and daunting, at Talú, we are dedicated to helping you unravel its complexity and empowering you to harness its beauty and potential within the comfort of your home or for your brand.

Let’s start this journey by learning how to make iron water for dyeing!

The power of iron water

In the vast palette of natural dyeing, iron water stands as one of my most favourite tools that offers versatility and depth to your dyed creations. It’s a mordant—this means that it’s a substance that enhances the permanence of natural dyes on fibres. It is also a colour modifier, allowing you a wider colour range from a single dye source.

Iron water, derived from a simple chemical reaction (I won’t bore you with a science lesson – don’t worry), holds the power to transform the tones of plant-based dyes, producing a spectrum of shades that range from subtle greys to rich charcoal blacks.

What is iron water and what is it used for?

Iron water, also known as iron liquor or iron acetate, is a solution made by dissolving iron compounds, often ferrous sulfate or ferrous acetate, in water. It is an essential tool in the world of natural dyeing and textile arts. Iron water serves as a mordant, resulting in a deeper and longer-lasting colour on fabrics.

Iron water can:

  • Shift the colours of natural dyes to “sadder” or darker ones when used as a modifier (aka after the dyeing process, take a look at how it’s done in this video)

  • Be used as a mordant before the dyeing process (we spoke about this in detail in this article)
  • Be used for soaking vegetation before printing in the eco-printing process

In essence, learning how to make iron water for dyeing means getting to witness how iron water empowers dyers to unlock a wider range of colour possibilities and creative expressions in their textiles. While it’s a relatively simple solution to create, the effects it imparts on your fabrics will leave you in complete awe. 

How do you use iron water for eco-printing/dyeing?

Trust me when I say that using iron water for eco-printing can add an intriguing dimension to your designs. You can take a look at our detailed explanation of eco-printing here, but in short, it’s a method of transferring plant pigments and shapes directly onto fabrics. 

How to use iron water for eco-printing:

  1. Begin with a natural fibre fabric that’s pre-mordanted with alum to facilitate dye absorption.
  2. Select an array of leaves, flowers, or plant parts with distinct colours and shapes that you’d like to use. Arrange them on your fabric.
  3. Lightly spritz or brush diluted iron water onto the fabric, where the botanicals are placed.
  4. Fold the fabric to encase the vegetation, creating a bundle. Secure it snugly.
  5. Steam the bundle or gently boil it to set the eco-print. This encourages plant pigments to transfer onto the fabric.
  6. Once cooled, carefully unwrap the bundle and witness the enchanting patterns and intricate designs left by the plants.
  7. Let the fabric dry fully to set the print. Gently rinse to remove excess dye.

The interaction of iron water with botanicals results in captivating dark outlines and shadows, adding complexity to your eco-print, that I know you will absolutely adore!

How do you make iron water mordant?

Learning how to make iron water mordant involves dissolving iron compounds in water to form a solution that can be used in the natural dyeing process. Here’s a step-by-step guide for you that is incredibly easy to follow:

Materials You’ll Need:

  • Old rusty bits (nuts, bolts, nails, etc.)
  • White vinegar
  • Water
  • Non-reactive container (such as glass or plastic)


  1. Carefully place a handful of rusty bits inside your non-reactive container a (be careful not to poke or cut yourself!)
  2. Fill the cup halfway with white vinegar
  3. Fill up the rest of the jar with water
  4. Loosely screw on the lid and let it sit for at least a week
  5. You’ll notice the liquid turns colour to an orangeish or greyish tone
  6. After a week, you’ll be ready to use your iron solution! Simply strain the liquor into another container, and you can start using it for mordanting, modifying or eco-printing your fabric.

Bonus step 

Label the Container: It’s important to label the container with the contents and the date of preparation. This helps you keep track of the solution’s age and purpose, as well as avoiding catastrophic mix-ups!

You can also make iron water by dissolving store-bought ferrous sulphate or iron sulphate crystals in water. Start with 2% of the weight of the fibre you want to dye. So, if you want to dye 100g of cotton, dissolve 2g of ferrous sulphate in water. If you want to achieve darker colours, add more crystals little by little until you’re happy with the result. You can buy ferrous sulphate from most of my recommended dye suppliers around the world. It is usually available in garden shops too.

Things to keep in mind

Remember that a little iron goes a long way, so start by using very little amounts and incrementally add more if you’re not happy with the results – iron can be corrosive to fibres (especially protein ones like wool and silk) when used in excess.

Please be cautious when working with or creating iron water. ALWAYS wear gloves when handling iron water, and make sure to keep it away from children or pets, as it can be lethal if accidentally ingested!

Explore the magical world of mordants and natural dyeing

Learn everything you need to know about the natural dyeing process, what textiles and fabrics to use, how mordants work and everything in between with Talú. 

Our mission is to demystify the art of natural dyeing and provide you with the tools and knowledge you need to embark on this captivating journey. Whether you’re an aspiring home dyer eager to infuse your fabrics with the hues of nature or a brand seeking to incorporate sustainable and eco-friendly practices, I’m here to guide you