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Make Your Own Iron Water

Iron water is an easy and intuitive mordanting method you can make with things that are already in your home!

Immersing fabric in iron mordant bath.

Mordanting is arguably the most important, yet often overlooked, part of natural dyeing. I think it's also one of the most intimidating parts about getting started with natural dyes.

What is a mordant? What mordant to use? Where to buy mordants? How much mordant to use? And safety of the mordant are questions I get asked all the time.

Answering these questions in depth can take several hours and are most easily explained in a workshop, so I find myself pointing people to homemade iron water to get started.

Homemade iron water can be made with things you most likely have lying around - vinegar, water, a glass jar, and rusty metal pieces like old nails. Just like that you can make an iron mordant and start experimenting with natural dyes!

Pouring out a little bit of iron water to dilute in fresh water.

How to make iron water:

To make iron water start by collecting the following ingredients:

- Rusty metal bits (old screws or nails, for example)

- A glass jar (I like to use the tall glass bean/chickpea jars)

- White vinegar like apple cider or cleaning vinegar

- Water


  1. Add the rusty metal bits to your glass jar.

  2. Fill the glass jar half-way with water and half-way with vinegar. Give it a nice stir before closing.

  3. Every other day take the lid off and stir the solution to oxygenate.

  4. After two weeks, you should have a crazy-looking orange liquid that smells like iron (also smells like blood). When the water has this orange color, it's ready to use!

  5. As you use the iron water, keep adding vinegar and water to the jar to keep the solution full.

**I like to have at least two jars of iron water so I can alternate their use. As I use one, the other rests.

How to use iron water:

Using iron water is also much more straightforward than conventional mordants because you don't have to measure a specific percentage in relation to the weight of fabric.

Instead, iron water is a much more intuitive method where you simply dilute a splash of iron water into a bucket of fresh water. The amount of iron water you use and the amount of fresh water depends entirely on the size of your fabric. Your fabric should be able to soak and float freely in the bucket of water.

Leave the fabric to soak for a few minutes up to an hour depending on the depth of the orange rust color your wish to have as a background. Then remove from the iron water and rinse through fresh water to decrease iron stains.

Now voila! - you have an iron-mordanted fabric ready to eco print, bundle dye, or immersion dye.

A few notes on iron as a mordant:

*Iron is both a mordant and a color modifier. It saddens and darkens colors like turning some yellows to greens, pinks to stormy purples, and tannins to a blue-grey. If you want to achieve a bright yellow color, for example, iron is not the mordant for you.

*Because of this colour-changing property, iron is most commonly used as a color modifier in immersion dyeing. However, it is this darkening property that makes iron the perfect mordant for ecoprinting bold, dark prints.

*Iron is a super potent mordant, so there's no need to pour out the whole jar whenever you go to use it. Pour out a splash to test and then add more if needed. If you're mordanting many pieces of fabric, start with a splash and then add refresh splashes of iron water between pieces.

*ON SAFETY: Iron is one of the most common minerals in the world and it's part of our every day lives (it's even an important part of our diet). However, in strong concentrations it can have a irritating and drying effects. For this reason, please wear gloves when working with iron water and be particularly careful with children's skin which is much more sensitive.

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