Iron mordant

The Iso Dye Club ecourse reflection

The live round of the Iso Dye Club has come to an end, although new students are still welcome to join and will be able to work through the ecourse at their own pace. It has been the most wonderful, inspiring whirlwind of an adventure. I feel so grateful to all the people who threw themselves into it with such enthusiasm and dedication, sharing their beautiful creations on Instagram and in our private group.

It has been such a good way to spend this quarantine/isolation time, hopefully for my students but also for me personally. I really appreciated staying busy, and feeling uplifted by everyone’s kind, supportive comments.

I’m also really glad that I offered it as ‘pay what you can’, to make it accessible to lots of people, especially at this time when so many of us are out of work or underemployed. Going forward, I want to bring this pricing model to more of my business, because it is a small way that I can help to create a more equitable world. Or as Charles Eisenstein puts it, The More Beautiful World Our Hearts Know Is Possible.

I want to share some of what we did in the course, because I really enjoyed creating simple lessons using materials that people would be able to access easily at home or in their neighbourhood, yet still get some stunning results. This craft doesn’t have to be complicated or precise. At it’s most basic, you just put leaves on paper or fabric, hold it together somehow and heat it up! And I encouraged everyone in the course to embrace the results they got, because sometimes in eco-printing, as in life, we don’t get what we expected and it can be very healing to learn to accept this.

Week 1: Rolled Bundles

For Week 1, we started with some simple rolled bundles, on both paper and fabric. We rolled around jars and cans – even rusty cans, if people were lucky enough to have these highly coveted, utterly magical eco-printing tools!

We used plain fabric and paper, to see how even the most simple technique could still give us some beautiful colours and patterns:

Week 2: Simple Homemade Mordants and Binders

In Week 2, we prepared our fabric and paper with homemade iron mordants and with protein binders (from kitchen scraps of yogurt, cow’s milk, nut milk or other protein-rich liquids). As well as leaves and flowers, I also demonstrated with some ingredients from the kitchen – onion skins, tea leaves and a sprinkling of turmeric – because some of the students were in isolation in apartments, or still emerging from the depths of winter. Here you can see the different colours and strength of results on plain cotton, and that prepared with a protein binder and iron mordant (from left to right).

Week 3: Folded Bundles

This week, we folded our paper and fabric and cooked them in dyebaths. On paper we experimented with creating different amounts of colour in the background. These bundles are both the same paper with the same leaves, cooked in the same dye bath, but I shared a simple trick for creating either dark or light backgrounds:

And on cotton, we created some shibori patterns around our leaf prints. This was one of my favourite lessons from the whole course. The leaves were eco-printed on fabric prepared with a simple yogurt binder, with a few tricks to get these vibrant results:

Week 4: Fun Things to do with Pale Results

When eco-printing, it is inevitable that some of your results will be pale or uninteresting. So we finished the course by exploring 3 ways to improve our pale prints. One option was to re-print the paper or fabric, with the addition of iron to bring out more colour and detail:

Another option was to draw over our paper eco-prints, either what we could see or what we could imagine. I shared some simple tips to encourage even the most reluctant artist to give it a try:

And we finished the course with a bonus lesson, because I wanted to thank everyone who was involved. So we used some of our pale fabric results to create some mini shibori moons:

This is another contender for my most favourite lesson. Sometimes the marks and leaf prints already on the fabric creates the most wonderful serendipitous results:

 

I hope you enjoyed this peek into the ecourse. If you are interested in joining us, I have left enrollments open because I want this course to be available to anyone who wants to be comforted or inspired by the magical combination of plants, creativity and community. Read more or join us here – the sliding scale starts at about the price of a coffee!

And whether you are enrolled in the course, or just enjoying this preview, I’d love to know which week or lesson is your favourite?!

Homemade iron mordant: what factors affect mordant quality?

Making an iron mordant is simple – get some pieces of iron, preferably rusty, put them in a jar and cover with vinegar. Let this sit for a couple of weeks, or until the liquid changes colour, and then use. (I go deeper into this method in my eco-printing ebook, Gum Leaf Alchemy).

But there are different factors affecting the quality of iron mordants. Here’s three pieces of cotton cut from the same piece of fabric and eco-printed with the same eucalyptus leaves, but with quite different results:

The difference between each sample was the quality of the iron mordant used. Let’s take a closer look at each.

Sample 1: A poor quality eco-print 

The mordant on this piece had been diluted with water a few days before eco-printing. It was a strong mordant that I was trying to dilute. The results are very pale and fuzzy:

The problem is that the vinegar is a vital component of the mordant because of its acidity. When water is added to iron mordant, it raises the pH and changes the iron from a dissolved form to a solid form. This is sometimes quite visible, it looks almost like the mordant has curdled. In this state, during the mordanting process it stays suspended in the liquid rather than bonding to the fabric.

This process is not immediate (otherwise it would not be possible to put iron mordant into water to mordant fabric). But it will be visible if you save any leftover mordanting water for a few days or longer, especially if it was quite strong. You will be able to observe the iron separating into small clumps and settling at the bottom of the container. 

So, the moral is don’t add water to your mordant. If you have an overly strong mordant, you can either use less of it or add vinegar to dilute it.

Sample 2: A mediocre eco-print 

The mordant on this piece was very old, and had been soaking for over 2 years. Although the mordant itself looked great, very dark and strong, the prints are fairly washed out, without the crisp detail I sometimes get on cotton:

The reason for this is that vinegar will lost its acidity over time, creating a similar problem to adding water to a mordant. Ideally you will be using your mordant regularly, and topping it up with more vinegar each time. If you have a very old mordant (unused for 6 months or longer), try adding new vinegar, letting it rest at least a few days before you use it again. If you still get disappointing results, you may need to make a new mordant instead.

So here the lesson is that the colour and darkness of the mordant won’t necessarily predict results. And that it is important to keep topping up your mordant with vinegar.

Sample 3: A high quality eco-print 

This last piece was made from a mordant that was only 2 months old but contained a lot of rusty metal so was a good strong colour. There is crisp vein detail on each leaf and lovely blue dots dappled across the brown leaf prints:

These are optimal results for eco-printing on cotton – crisp, detailed and dark. The pale prints still look nice but will fade much faster.

This sample shows that iron, vinegar and the right amount of time (not too little, not too much) are all you need to create a great iron mordant.

Other iron mordant considerations 

Often people think that the brightness or paleness of a print is caused by using more or less mordant. But actually, other factors are far more important. How well the fabric was scoured, how much pigment is in the leaves, and the quality of the mordant can all drastically impact the results you get. The fabric will only absorb a certain amount of mordant, and a small amount is surprisingly potent. So even when using homemade mordants that aren’t measurable, it is not easy to drastically over- or under-mordant your fabric.

One final mordant variable is when you have used up the liquid of a mordant, but have iron sludge at the bottom of the jar. Once you top it up with fresh vinegar, you need to let it sit for a few days or longer otherwise it will also give pale results.

So if you have been getting poor or mediocre results when eco-printing on cotton, I encourage you to consider whether your mordant might be the reason why. If you need more help with getting great results on cotton, check out my eco-printing ebooks for in-depth information about every step of the process.

Pin this information for later:

Shibori eco-printing on cotton

Following on from my recent post about combining shibori dyeing and eco-printing on wool, here are some similar effects achieved on cotton. I really enjoy combining organic eco-prints with geometric grids or lines from shibori dyeing methods.

Liquidambar leaves eco-printed on cotton with iron and alum mordants

This pattern was created by folding the tshirt up into a small bundle, adding liquidambar and Japanese maple leaves as I went. Then I tied it tightly with string and submerged it in a dye bath of eucalyptus bark and iron, cooking it for about 1 hour. The fabric was mordanted with homemade iron and alum mordants, following the instructions in my ebook, Gum Leaf Alchemy.

Cotton naturally dyed with eucalyptus leaves and bark

Here is a close up of a similar pattern, this time with eucalyptus leaves and an iron mordant. The large section of lines show which part of the tshirt ended up on the outside of the bundle, wrapped tightly with string. There are smaller sections of lines where other parts of the tshirt were also on the outside of the bundle, because of how it was folded.

Creating a geometric grid overlaid with eucalyptus leaf eco-prints

This long-sleeved tshirt was also folded up, but into a smaller bundle which was pressed between two square pieces of hardwood. This helped to create a very even, geometric pattern to contrast with the organic shape of the leaf prints. This piece was also mordanted with iron and alum.

Rose leaves eco-printed on cotton by Gumnut Magic

This piece of fabric was mordanted with iron, covered in rose leaves and folded into large squares. I pressed the fabric between 2 tiles, clipped the tiles together then submerged the bundle in a dye bath and cooked it.

If you would like to come back to this idea later, you can pin the below image.

Examples of cotton clothing naturally dyed with 2 different techniques: shibori and eco-printing

Combining iron and alum mordants for eco-printing

Although iron is my trusty favourite mordant- easy to make, relatively low toxicity, and easy to dispose of- I have been experimenting with alum lately. My first results of eucalyptus on alum were not very promising. Fluro yellow is not my favourite colour. But then I tried double-mordanting, combining both iron and alum. I hoped that the saddening effect of iron would help tone down the brightness of the alum and bring in more subtleties. And it worked beautifully!

The alum has brought out these beautiful oranges and yellows from the eucalyptus leaves, while the iron gave more depth and detail:

Double mordanted with alum and iron

The colours vary according to how much alum and iron are used, and the particularities of each piece of cotton too. It is important when eco-printing to be open to the different possibilities and to embrace the results you get. Each print is a gift from the leaves, so be grateful.

How to mordant cotton

This onesie was bit of a failure originally. It had pale, faded grey prints, probably from not being scoured properly. The alum and iron mordanting prepared it well for a second round of eco-printing, and it was transformed into one of my favourite pieces so far. Aren’t the gumnuts exquisite?!

Mordanting cotton with alum and iron

To do this double mordanting, I scoured the cotton, gave it a short dunk in one mordant, let it dry and cure, then dunked it in the other. Then I eco-printed the fabric in my usual way, using the instructions I share in my ebook Gum Leaf Alchemy.

Combining alum and iron mordants to eco-print on cotton
Combining alum and iron mordants to eco-print on cotton

If you’d like to learn more, I have a lesson about combining alum and iron mordants in my ecourse, Living Colour.