From time to time I get questions from my ebook customers, wondering why they have gotten pale or disappointing results when eco-printing on cotton using an iron mordant. There is no simple answer, because there are a lot of different variables that can affect results. In this post I will discuss some of the major variables, as well as ideas for troubleshooting the cause of pale prints.
When we eco-print, we use leaves, fabric and mordant. Each of these has its own set of potential problems.
Troubleshooting fabric variables
Fabric naturally contains oil and waxes that act as a barrier for natural dyes, preventing them from binding to the fabric. If you want to use new fabric, you need to scour it. Scouring is a form of deep washing that strips out the oils and waxes. Insufficient scouring can cause pale results. Make sure you follow scouring instructions carefully and rinse well afterwards with hot water. You can find instructions for scouring in my Gum Leaf Alchemy ebook , Intro to Cotton ecourse , or through a web search.
A simpler option to use old, well washed fabric. Often this takes up natural dyes even better than scoured fabric.
Another fabric problem can be not wrapping bundles firmly enough. The leaves need to be pressed firmly into the fabric, otherwise the dye will seep out into the water and cause pale, patchy prints, rather than being absorbed directly where it is touching the fabric, in a perfect leaf shape.
Troubleshooting leaf variables
There are two major leaf variables that can cause pale results. First is the leaf itself and whether it actually has enough natural dyes in it. Some plants are great for eco-printing with and others just aren’t. And a particular genus may in general be good for eco-printing, but that doesn’t mean that every species in that genus will be. For example, some eucalyptus species will produce vivid orange or red prints on wool, while others don’t even create a print. And even species that usually give good results can be affected by growing conditions, weather and rainfall, as well as the time of year that you pick the leaves.
The second leaf variable is how it has been collected and stored. In my ebooks and ecourses, I recommend collecting fresh leaves and soaking them in water for a few days or weeks, to remove the water soluble tannins that can cause bleeding on iron-mordanted fabric. Soaking the leaves makes some of the dyes more available, so you get brighter and clearer results that with fresh leaves. But soaking them for too long can also cause pale results.
I recommend doing your own tests – compare fresh leaves with some soaked for a few days, a week and 2 weeks, all eco-printed on the same piece of iron-mordanted fabric and cooked for the same length of time. This will help you begin to see what works best for your local leaves.
I explore all of these leaf factors more deeply in my ebook, The Leaf Guide.
Troubleshooting mordant variables
Homemade mordants can be a little tricky, because they are all different strengths and the quality can vary, depending on what metal you used for it and how long it has been brewing. In general, as long as your mordant changes colour as the iron soaks in the vinegar, it is usable.
To test the quality of your iron mordant, try to control the other variables as much as possible. Use old, well washed cotton and some reliable leaves like rose and Eucalyptus cinerea. I recommend using them fresh, so you don’t accidentally use leaves that have been soaked for too long. Press your bundle between tiles and secure with clips, to ensure good pressure. Cook on a low boil for 1 hour, then let cool in the pot.
If you get strong results, you will know that your mordant is okay, and you can start experimenting with soaking the leaves for different lengths of time and using other fabric.
If you get pale results, it tells you something is probably wrong with your iron mordant. One possibility is that it is too old – iron mordant gets weaker over time as the pH changes. Another possibility is that the piece of metal you used wasn’t the best for making mordants with – try to find a very rusty piece of iron to make a new mordant with.
Does the amount of mordant matter?
Homemade mordants vary in strength, so it is not possible to give precise instructions like ‘use 4% of the Weight Of Fibre’. Some people worry that they have used too little or too much. Don’t be too worried about the amount though – the fabric will only absorb some of what is in the mordant bath, and it is quite a forgiving process.
A small amount is surprisingly potent, and it is rarely the case that people haven’t used enough. If you are doing a large batch of mordanting, just make sure that you add a small amount more after soaking each piece of fabric, to replace the mordant that it has absorbed.
Using too much mordant can be a problem however. If your fabric yellows significantly after being in the mordant bath, you have used more that necessary. Try to flush some off by soaking it in plain water. Too much mordant will damage the fibres and make them tear and break down much more quickly.
Enjoy them as is. Let go of the idea that eco-prints have to look a certain way, and just enjoy what you have received from the plants.
Re-print them: re-mordant your fabric and add a new layer of leaf eco-prints. This is also a good thing to do when eco-prints have faded from sun exposure. Fabric generally takes up natural dyes much better the second time.
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?!
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.
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.
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.
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.
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.
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.
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:
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.
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?!
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.