September 23, 2021

Painting with iron water

Today I will share a really simple way to make a pattern with iron water. Iron or rust water can be used as a “color changer” with almost all types of plant dyes. When the iron plant comes in contact with the dyed fibers, the color changes to a deeper color: we say that iron “saddens” dyes. To get a darker color, you can replace an entire piece of fabric with iron, or you can create a darker pattern by applying iron with a paint brush. Painting with iron water is one of my favorite ways to create patterns: it’s so simple and not complicated at all!

There is a section on iron water in my Botanical Color book at your fingertips. I will show you how to use an iron to darken a whole piece of fabric and paint patterns. I will give additional tips to create examples in this blog post.

1632401769 428 Painting with iron water Rebecca Desnos

What do you need

  • Piece painted with plant dyes (my Botanic Color book at your fingertips will help you get started)
  • Iron water

    • iron sulphate crystals to be mixed with water.
    • for homemade iron water: soak metal pieces in a jar of water and vinegar for a few weeks (full details in my book).
  • Small jars or pots*
  • Spoon *
  • Paint brush
  • Protective coating for your table
  • Gloves to protect your hands *

* Do not use them to eat again


  • Do not spray iron water or ferrous sulfate crystals on your skin. The iron will stain your fingers and irritate your skin. I did not use gloves in these pictures, but I did wear gloves when mixing iron water.
  • Painting with iron water with small children. It is better to stick to food ingredients like other classes like milk coloring and tea coloring.

Let’s start

Choose the piece you want to paint. No need to paint recently – the iron will change the colors that have been painted for a long time. Make sure your fabric is completely dry, then iron. It is easier to draw a smooth fabric than a wrinkled fabric.

Now let’s prepare iron water.

  • If you are going to use homemade iron water, pour a little liquid from your jar and filter any metal pieces or larger pieces of rust to leave a clear liquid. If the liquid you make at home is too concentrated, you may need to dilute it with fresh water.

1632401770 893 Painting with iron water Rebecca Desnos Fabric dyed with tea (left) and avocado skins (right)

  • Then I will show you how to make iron water with ferrous sulfate. Sprinkle about ¼ teaspoons of ferrous sulfate crystals in a small jar of warm water (about ¼ cups of water). A packet of ferrous sulfate lasts for years because we use less each time. I like to use warm water to help the crystals melt, then mix very well with a spoon. When mixed, the liquid is saturated with oxygen and the water will turn into a rusty orange. When completely dissolved, it is ready to paint on the fabric.
  • Tip: Do not want to concentrate the iron water too much, as it can sit on the surface of the fabric and then spread to the rest of the fabric when washed, darkening it all.

Now place the dry cloth on the table (with a protective cover if you choose) and plan your pattern roughly. We will paint the surface of the fabric with water drops. The resulting patterns are soft and natural, as water flows along the fabric. The less iron water you draw, the finer and more detailed the patterns will be. If you apply iron water splashes, the iron water will flow unexpectedly into the fabric, which can be fun to play with!

1632401770 466 Painting with iron water Rebecca Desnos Tea-dyed cloth (left) and pomegranate skins (right).

It may take a few seconds for the sample to appear, and it may take longer for the sample to darken completely. When you first start painting, it can be helpful to wait for the first part of the pattern to appear before continuing.

Test on a piece of cloth to understand how water passes through the fibers. The result will vary according to different fabric types.

Try drawing iron water droplets to create a tear pattern. The painted pattern below is from the Botanical Color at your fingertips. For this example, I used homemade iron water. The fabric was thick linen and did not bleed, so the pattern is accurate. The fabric samples in the photos above are on a thinner fabric, where the iron water bleeds more.

1632401770 505 Painting with iron water Rebecca Desnos

Organic cotton linen dyed with avocado skins.

After finishing the painting, dry the fabric completely.

After that, we will wash the fabric to remove traces of broken iron particles. Because we use dilute iron water, there is very little iron to wash, so the surrounding fabric is less likely to be affected during washing. The goal is to use enough iron to react with the paint, and not more. If the iron water is too concentrated or if the iron crystals are not completely dissolved, there is a possibility that there is excess iron on the surface of the fabric.

Wash the fabric in a flat bowl. If you want, change the water and rinse again.

Wash the fabric to remove excess iron. I wash my fabric with a natural liquid – I use BioD. I wash my hands for small pieces of fabric and use a washing machine at 30 ° C for clothes.

1632401770 301 Painting with iron water Rebecca Desnos Fabric dyed with avocado stones – linen (top) and bamboo silk (bottom)

Additional notes and tips:

  • If you use the soy milk method to pre-clean your fabric before dyeing (as mentioned in my book), it can create an almost waterproof surface for the fabric. This means that it may sometimes take some time for the water to soak into the fabric. I think this happens more in some types of fabrics than in others. If this seems like a problem, allow the water to settle on the surface of the fabric and immerse after a few seconds. After the iron is absorbed, the color will change.
  • Some plants that contain iron, such as nettles, do not change color very noticeably from iron water. The paint pot is darker than the naturally occurring iron.
  • Some very pale dyes, such as dandelion flowers, react sharply with iron. Get ready for some surprises!
  • If you dye the garment with iron water, depending on the thickness of the fabric, the iron may soak into both layers of the fabric and darken the bottom layer. I like to cut a large piece of cardboard and roll it inside the dress so that the water can’t reach both layers. Paint one side, then dry, then turn and paint the back.

1632401770 676 Painting with iron water Rebecca Desnos

For more natural coloring step-by-step lessons, check out my book (and e-book) Botanical Color at your fingertips.

1632401771 919 Painting with iron water Rebecca Desnos

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