Eco-printing on cotton – Gumnut Magic

To soak or not to soak?

November 17, 2021 November 17, 2021

Way back in 2016, when I had just begun selling clothes under the label Gumnut Magic, I had a lot of interest from other natural dyers about my eco-print technique. Back then people were mostly eco-printing on wool so I had a lot of questions about how I was managing to get clear, bright prints on cotton. At that stage I’d been eco-printing for a few years and had developed a technique that worked for me. I decided to write an ebook to teach my method.

My first ebook was Gum Leaf Alchemy, so named because I focused specifically on eucalyptus (or gum) leaves. This ebook was specifically about eco-printing on cotton using an iron mordant. Part of the method I described in that ebook was to pre-soak the leaves in water for a few days or a few weeks before eco-printing. This is a way to get clear, bright prints with vein details and variety of colour:

Unfortunately, I now see some dyers swearing that you need to soak all leaves for any type of eco-printing, while others denounce the idea of ever soaking leaves.

But I never said that we should always soak leaves or that it will always give better results. There is definitely a time and place for it. I’ve done lots of tests over the years which have helped me to understand that sometimes soaking leaves is very helpful and sometimes it is not. I’ve also done research into the science of natural dyeing to try to understand the different chemical reactions that occur when using fresh or soaked leaves. I continue to learn and experiment, and I will continue to share my findings. In this post I hope to clarify when it can be useful to soak leaves, and when it is unnecessary.

On tannins and soaking

When I wrote Gum Leaf Alchemy I was mostly eco-printing with eucalyptus leaves and I had found that soaking is an important step for many species of eucalyptus – because of the high tannin content which causes bleeding and patchy prints. But also because they are sometimes quite a tough leaf and sometimes the other colours besides blue are only accessible after soaking. Here you can see the blue, patchy and less detailed prints that can come from fresh leaves:

That said, some fresh eucalyptus leaves give great results, particularly when sourcing leaves from healthy street trees, so it is always worth experimenting with both fresh and soaked leaves to see if there is a difference. It’s a large genus of plants with many different species growing in different conditions, so of course there will be a lot of variation.

For my third ebook, The Leaf Guide, I researched more about tannins and came to understand the mechanism by which soaking leaves improves results. There are three types of tannins: gallic, ellagic and condensed. Gallic tannins react strongly with iron mordant, causing the blue and grey bleeding through the fabric that you can see below:

Luckily gallic tannins are hydrolysable (water soluble), which means that soaking the leaves reduces or removes them, thus reducing or eliminating the bleeding. In that ebook I also noted that it is always worth doing your own tests with your local leaves, rather than assuming that soaking will make a difference. Sometimes it makes a big difference and so it is worth the effort, while other times the difference may be small and so you could decide that it’s not worth the extra hassle. And of course, you may love the dappled blue effects from the tannins interacting with iron, and prefer that to clearer prints on a plain background. There is no right or wrong in eco-printing, just different possible results!

Below I have tried to summarise the circumstances in which pre-soaking your leaves before eco-printing is a good idea, and when it is unnecessary or may even produce worse results. The basic summary? For most methods of eco-printing, it is better to use fresh leaves!

When to soak leaves

If you are eco-printing onto a plant based fabric (cotton, linen, viscose etc) AND you have pre-mordanted your fabric with iron, then pre-soaking the leaves in water for a few days or longer may reduce bleeding and create clearer prints.

Put another way, I only recommend soaking leaves if you are using the specific technique that I write about in Gum Leaf Alchemy. Even better, only soak them if you have done tests with your local leaves comparing the results from fresh and soaked leaves, so you can be sure that it is a necessary step. While I find that pre-soaking improves results more often than not, for some leaves it makes no difference and, occasionally, it causes worse results for some leaves.

It is also important to understand that removing the gallic tannins may result in clearer prints, but at the expense of having the positive properties of these tannins – namely that they help natural dyes bind to fabric and can also provide a colourfast dye. Gallic tannins actually have better wash- and light-fastness than the condensed tannins which are not water soluble. So even though removing some of the gallic tannins mean that the different colours of the condensed tannins become more visible, your prints will not be as colourfast.

Also, you do want to be careful not to soak your leaves for too long. After some weeks of soaking, these maple leaves gave very beautiful, detailed prints with different colours from each side (top row). But after soaking for several months, the prints were paler which means they will be less colourfast (bottom row):

The interesting thing about these maple prints is that they show that the tannins leach out slowly over time. So when soaking leaves, we want to be hitting a sweet spot where enough of the tannins have been removed that the prints aren’t bleeding, but enough remain that you can get the benefits of them outlined above. There’s no way to accurately judge this, except to aim to soak the leaves for as short a time as possible. I have found it valuable to do tests comparing results from fresh leaves and leaves soaked at increments of 3 days, 1 week, 2 weeks and 3 weeks, so that I can try to find that sweet spot. I encourage you to do your own tests with your local leaves.

I’ve also detailed some of the results of my experiments in The Leaf Guide. In this ebook, I show examples of 25 different leaves eco-printed on cotton, with information about how long I soaked the leaves for each sample, and whether soaking made much of a difference.

Here’s an example of a cotton tshirt pre-mordanted with iron, where the leaves where soaked for a perfect amount of time. The prints are still strong and not washed out, there is no bleeding, and there is a good range of colours and some very nice vein detail:

When not to soak leaves

If you are eco-printing on wool, it is unnecessary to soak your leaves.

This is true even when using iron on wool (which you should always do sparingly). I think this is because the proteins in wool are able to bind more plant dyes directly where the leaves are touching it, rather than the excess dye bleeding through layers. It’s still okay to use soaked leaves on wool, if that’s all you have to work with, as long as you haven’t soaked them for too long. If you soak them for weeks or longer, you may notice the results become more pale.

If you are using any other mordant, it is unnecessary to soak your leaves.

As far as I am aware, the strong reaction and bleeding only occurs with the combination of gallic tannins and iron mordant. So if you are using alum or any other mordant, you can use fresh leaves.

If you are using iron dipped leaves on plant based fabric (either plain fabric or prepared with soy milk binder), it is unnecessary to soak your leaves.

This is a method I have been using more over the past few years, because it removes the need to keep track of how long leaves have been soaking for. And the combination of iron dipped leaves and fabric prepared with soy milk provides strong, colourfast results. I explain this process in detail in my new ebook, Soy Milk Binder for eco-printing and natural dyeing. Here’s some of the results I show in that ebook for eco-printing with fresh deciduous leaves, both plain and dipped in iron:

So why can you use fresh leaves if you are dipping them in iron, rather than coating the whole piece of fabric in them? My hypothesis is that because the iron is only on the leaf, and is only making contact with the same part of the fabric as the leaf is, there is no way for it to bleed through to the rest of the fabric. Whereas when you mordant the whole piece of fabric with iron, any tannin that hasn’t bound to the piece of cotton it is pressed against is going to bleed through and bind to any available iron mordant.

When comparing these results with the maple prints above, you can see that the results using iron-dipped fresh leaves are slightly different to the soaked leaves. There is a bit less crispness and vein definition when using the iron-dipped fresh leaves on soy milk binder. But for me, the convenience of using fresh leaves sometimes outweighs this.

So if you can use fresh leaves, why would you soak them?

Hopefully by now you understand that soaking leaves is useful just when using an iron mordant on plant based fabric, and that it is also possible to eco-print with an iron mordant with fresh leaves. It seems to me that there are three options for getting clear prints on plant based fabric, if you want to use an iron mordant. They have differing levels of colourfastness, and of ease of preparation:

Fresh leaves dipped in iron, on plain fabric

This is the simplest option, which requires no advanced preparation besides making the iron mordant. But results will be the least colourfast. A good option for testing new leaves, or if you want a simple method and don’t mind re-printing your clothing regularly.

Soaked leaves on iron mordanted fabric

This option has better colourfastness, and the fabric is simpler to prepare with iron mordant than with soy milk binder. But you need to be organised about soaking the leaves in advance. This is the method I teach in my ebook Gum Leaf Alchemy and my Living Colour ecourses. I like the results from this method the best, because when leave have been soaked an optimal length of time (not too short or too long), the results are bright and clear with lots of detail.

Fresh leaves dipped in iron, on fabric prepared with soy milk binder

This option probably has the best colourfastness, because you are getting the benefits of both soy milk binder and iron mordant. This is the method I teach in my new ebook, Soy Milk Binder, and in my ecourse of the same name. It’s a longer process preparing the fabric with the soy milk binder, but if you do an occasional big batch you’ll always have fabric ready to use, and you don’t need to worry about soaking leaves in advance. Using soy milk binder also means that you can dye the background of the fabric, either before or after eco-printing.

Final thoughts

There are many different ways to prepare fabric and to eco-print. I love working with iron mordant because it can bring out great colours and interesting details such as crisp vein lines. Because the gallic tannins in many leaves react with iron mordant, sometimes a little and sometimes a lot, it’s worth considering whether you mind this bleeding, and whether you want to take steps to avoid it.

I’d love to hear your thoughts. Was this post useful? Do you soak your leaves before eco-printing? Sometimes, always, never? Have you learnt anything from your own research and experiments?

The Iso Dye Club ecourse reflection

May 4, 2020 November 21, 2021

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?!

Introducing the Iso Dye Club

April 11, 2020 November 22, 2021

In this time of isolation and quarantine, I wanted to offer some moments of peace and joy. The healing power of nature and creativity. And so I have created the Iso Dye Club.

This ecourse is a gentle introduction to natural dyeing and eco-printing techniques, for cotton and paper. The focus is on making do with what we have. Simple methods and simple materials. Finding joy in the process and in unexpected results.

It’s also a chance to slow down, to connect with plants and with fellow artists/makers in isolation. Creativity and nature ground me, especially in uncertain and changing times. I look forward to sharing this with you too.

We’ll be using kitchen scraps to make natural dyes and binders, and eco-printing on paper and fabric that we find around the house. Here’s some results on printer paper:

This is a bit different from my other courses, because I wanted to offer something more affordable, and more accessible to those of you who can’t access fancy materials or lots of plants at this time. So our results might be softer and simpler, but this feels like good medicine for these times.

The course is 4 weeks long, with 2 videos each week that cover both paper and fabric projects. There’s also a bonus video to get you started, about natural dyeing with easter eggs. Here’s a preview:

If you are interested in this offering, click here to read more or to join us. There’s a lovely group already, beginning to share their results on Facebook, and on Instagram #isodyeclub.

You’ll have access to the course for as long as it exists, so you can do it in your own time and come back to it as often as you like.

Soy Milk Binder eco-printing module

January 15, 2020 July 20, 2021

Last year I created my eco-printing ecourse, Living Colour. It is a comprehensive guide to eco-printing on natural and semi-synthetic fabrics, using alum, iron and soy milk, and a whole range of techniques. But for those of you who are interested in just one topic, rather than the whole course, I have begun breaking up the ecourse into four modules: ‘Intro to Cotton’, ‘Advanced Cotton’, ‘Soy Milk Binders’ and ‘Wool and Shibori’.

I released the Soy Milk Binder module in November, and will make the rest of the modules available through 2020. Here are some samples of work by my students:

This lovely piece was eco-printed by Debbie Lucas. She prepared the cotton with soy milk binder, then used geranium and herb Robert leaves which have created a bright, layered pattern.

These soft, harmonious prints were created by Bobbi Stowers, using rose, passion vine and eucalyptus leaves. Again, the cotton was prepared with soy milk binder.

It is also possible to prepare fabric with cow’s milk, which creates a similar effect to soy milk because both are protein rich. Kathy Little has used this to great effect in this sample of eucalyptus leaves eco-printed on cotton. You can see how the cow’s milk makes the cotton take the dyes very similarly to wool, creating vivid orange prints.

You can view more samples of my student’s work in the Student Gallery on my ecourse website. There you can also browse the ecourse curriculums and some sample lessons.

Discharge eco-printing on cotton with logwood and geranium

October 6, 2019 July 20, 2021

Discharge eco-printing is a method that has been mostly developed and refined by Irit Dulman. She has some very useful information about this technique on her blog. It is a type of eco-printing where fabric is dyed a solid colour, then leaves are placed on top. When the bundle is cooked, some of the leaf acids and other compounds react with the solid dye and ‘discharge’ it, leaving a leaf print surrounded by colour.

As with other types of eco-printing, most people seem to do discharge printing on wool and silk. But because I prefer using plant-based fibres, I have been experimenting with this technique on cotton. This is my most successful piece so far.

I used logwood dye for the background, which has created a rich earthy purple. And I used 2 varieties of geranium leaves to create the discharge prints.

As you can see in this video, one variety creates far clearer discharge prints than the other. But I am happy with both, because I wasn’t going for an even, uniform appearance with isolated, clear leaf prints. I like the moodiness of this tope, which reminds me of night skies and fireworks and magic.

I am still very new to this technique. But here is what is working best for me so far: First I mordant my fabric with aluminium acetate, then soak it in a warm dye bath until it is the colour I want. I choose a leaf with good discharging potential (Irit Dulman shares many examples of these on her blog). Generally the back of the leaf discharges more, but I like to use both sides and see the different effects. After placing the leaves on the dyed fabric, I fold it up, clamp it between tiles and cook as usual.

Living Colour: Eco-printing on Cotton Ecourse

June 24, 2019 March 23, 2020

I am delighted to announce the release of my new ecourse, Living Colour, which explores different techniques of eco-printing on cotton. It’s my way of lovingly guiding you through the process if you are too far away to attend a workshop. We’ll be creating our own wardrobe of living colour, using the natural dyes in plants.

Eco-printing newbies are welcome as we will cover the basics of preparing leaves and fabric and rolling bundles. But we will also explore some things that I haven’t shared in any workshops yet, such as combining eco-print and shibori methods, and using a soy binder. You can view the trailer and curriculum or register now over at learn.gumnutmagic.com

Wrapping eco-print bundles

February 20, 2019 March 23, 2020

Here’s a quick video of how I wrap and unwrap eco-print bundles. Unlike many eco-printers, I don’t wrap around a stick or other firm object. I prefer to just fold the bundle in on itself and then tie tightly. This creates a semi-flexible bundle that fits easily into the dyepot.

This piece was mordanted with iron and eco-printed with eucalyptus leaves. If you would like to see a full video of the process in real time, with each step explained, please check out my eco-printing ecourse, Living Colour. It is such a beautiful and delighting process and I love to teach it to students around the world.

How long to boil eco-print bundles

February 19, 2019 March 23, 2020

When I first started eco-printing, I boiled my bundles for 3 hours. I got good results, so I kept doing this. But one day I noticed that after a short amount of boiling the leaves had already produced a lot of beautiful colour.

So I decided to take a more systematic approach to working out the optimal length of boiling. I made up a batch of small bundles using leaves from 3 different eucalyptus varieties on pieces of the same pre-mordanted cotton. I set them to boil, then removed them at 15 minute intervals.

I was suprised to see that there wasn’t much difference between the bundle that had been boiled for just 15 minutes (left), and the very last one which was left in for 1 hour and 45 minutes (right).

The colour of the leaves on the top sides did shift from brown to blue with longer boiling times, but the centre green and botton brown leaf prints didn’t really vary. The blue band on the right side print is from the piece of dowel that the bundles were wrapped around. This band got progressively darker and bled more the longer that each sample was boiled for, because wood has its own tannins.

Even though much of the dye has already emerged after 15 minutes, I do cook my bundles for longer, to ensure that the maximum amount of colour is transferred to the fabric and to really give it time to set. I find that about 1 hour is a good length of time when eco-printing on cotton. It’s enough time to get strong prints, while being mindful of energy use.

Shibori eco-printing on cotton

December 14, 2018 March 23, 2020

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.

Eco-printing workshop

March 22, 2018 March 23, 2020

Last weekend I ran my first full-day eco-printing on cotton workshop. I had a lovely group of enthusiastic women join me at my house to explore the theoretical and practical aspects of this method of natural dyeing.

We spent the morning talking about choosing and preparing leaves and fabric and making a mordant. I demonstrated a few ways to place leaves and wrap bundles, then it was their turn. It was so interesting to see the different ways everyone arranged their leaves.

We put our bundles on to cook while we enjoyed a shared lunch. Then it was time for the most exciting part of the day- unwrapping! We took turns unwrapping our bundles, and there were many exclaimations of joy at the beautiful leaf prints that had emerged on our fabric.

Again, it was so lovely to see the different results everyone got. We each dyed two pieces of clothing and many of us got quite different colours on each piece.

Everyone left with wonderful prints, but more importantly with the knowledge to be able to go home and continue this on their own. I had a great day and am looking forward to teaching many more workshops. To see what I have scheduled, check out the ‘workshops’ tab on the menu.