Friday, 7 September 2018

Iron Blanket in a Plant Dye Bundle - A Better Method

It's over a year since I first wrote a post about using an iron blanket. I remember doing more bundle dye experiments when all the leaves changed colour in 2017 and I did get closer to the iron blanket effects I hoped for
A couple of weeks ago, noticing some of the oak leaves were already falling, I managed to find the pieces of cloth I printed last year, but really couldn't bring to mind quite how I had done it. Unfortunately, last autumn I had little headspace to spare and wasn't blogging. To save me forgetting again, today I'm writing a reference blog about how I have now retraced my steps and moved a bit further forward.
Taking the steps in order, first scour some natural fabric by washing it with soda ash to take off any oils, waxes or stiffeners. Next, mordant wool and silk with alum, cotton and linen with aluminium acetate. Then dye it by simmering the fabric in a plant dye bath. This picture shows linen, silk and wool pieces, all dyed with Dyers Chamomile flowers.

Now the iron blanket. Home made iron acetate solution, made by leaving rusty metal in a mixture of water and vinegar for weeks or months, is inevitably of variable and unknown concentration. I'd say that in practice, the results of using the contents of my rust filled jam jar suggest my homemade solution is usually pretty weak. For the purpose of investigation, I made up a measured solution of ferrous sulphate, pouring 100ml boiling water on 10g of the powder and stirring, so that I would know 10ml contained 1g of iron. Using a syringe, I drew up 20ml and added it to a washing up bowl half full of water. By eye, that 2g of ferrous sulphate gave the bowl a very pale orange colour. My blanket fabric was a fairly thick cotton, cut from an old curtain. It was soaked in the bowl of iron solution for several hours and squeezed out just before using it.

My dyed fabric had been dried without rinsing, straight from the dye bath. I put a piece of linen (half the leg of some loose trousers) to soak in plain water and collected a selection of leaves from the garden, plus oak and sycamore from the trees down the road. I unrolled some baking parchment on the table, smoothed out the wet dyed linen on its surface, laid out the leaves, some face down and some face up, then placed the iron blanket over the top. All the layers, baking parchment, dyed linen, leaves and iron blanket, were rolled up around a section of plastic drainpipe, then bound firmly with string.
The completed bundle was stood on a trivet inside a very large pot with water in the bottom, the lid was put on and the pot was heated to the boil before turning the gas down low to keep steaming the bundle for two hours. I left it overnight to cool and next day, unrolled it. Below is a photo of the dyed linen and the iron blanket, laid out side by side. Not a ravishing success, but much can be learned from looking at it. As expected, the leaves varied in their affinity for iron, which I believe may be due to the amount of tannin each species contains. Most had made blacker shapes where the underside of the leaves faced the iron blanket than where the underside of the leaf had faced the dyed cloth.

This effect showed up even more clearly once the iron blanket had dried out. What happened on the dyed linen is less obvious, though much more important. I decided that the central oak leaf in this photo had worked best as a resist by being laid with its underside facing the iron blanket, as the yellow is brighter than the adjacent oak leaves which had been laid with their undersides facing the linen. I had rather hoped that where the iron blanket had been in direct contact with the linen with no leaf in between, the iron would have modified the chamomile dye to a warm green. As you can see, the yellow actually went more of a dark khaki.

Unexpectedly, the Japanese Maple and the ginkgo leaves seem to have sucked the yellow dye out of the linen. I had read people recommending both of these types of leaves in the past and been disappointed that I couldn't get any dye or iron dip print from my trees. I am delighted to discover that the damn things actually work by 'exhausting' other dyes :)

The hardy geranium aka cranesbill leaves had left beautiful, if subtle prints, full of detailed edges and veins. I grow several varieties, because they make lovely prints in contact dye bundles when dipped in iron. In spring, some types will print with their own yellow dye. Sorry, I don't know the names of the different kinds, but this is what the plants look like at the moment.

Anyway, since they will soon die back when the cold nights come, I thought I would include cranesbill leaves in the next test piece, this time a good silk scarf. I laid the leaves on densely, hoping for pale shapes from the exhaust effect of maple and ginkgo leaves, fine patterns from the cranesbill and bold yellow resist shapes from the oak.
Unrolling the first turn of the bundle looked great. Unrolling more turns revealed much darker silk and far less clarity of leaf prints. Time for a cup of tea and a fag and a careful think. I decided that the baking parchment wasn't preventing iron from the blanket soaking through to the layers rolled underneath and there was just too much iron everywhere. 

First modification of the technique was to reduce the amount of iron. For my next silk scarf I used an iron blanket cut from a thin, worn out cotton bed sheet. It was soaked in the same washing up bowl of iron solution, but wrung out firmly after soaking. I had read before about people using layers of clingfilm in their bundles, but never fancied the idea.
Clingfilm isn't biodegradable or reusable and anyway, I thought it might melt during the steaming and weld itself onto the bundle. Funny how buggering up an expensive piece of silk has changed my attitude, I felt quite ready to give cling film a go. After steaming, the bundle looked as though it had been shrinkwrapped.
Happily, the clingfilm peeled off with no trouble. It had confined the iron from the blanket, allowing it to work only on the single layer of silk against which the blanket was pressed. With less iron available from the thin cotton blanket, the background colour looked much less gloomy, though you can see deeper lines where the string had squeezed the dyed silk most tightly. Taking away that shroud of darkness made it much easier to examine the actual leaf impressions. The ginkgo had had the most powerful exhaust effect though I could now see that the sycamore had also reduced the strength of the chamomile dye on the linen.
With the clingfilm there to keep all the dye localised under the leaf, for the first time in my experience, the Japanese maple had left its own pink dye and the purple smoke bush had added a blueish green. Thick oak and fern leaves had acted purely as resists, keeping the iron blanket off the silk but neither exhausting nor adding anything to the dyed linen.
I am truly delighted to have made a good iron blanket printed silk scarf. With less iron in it, even the effects on the iron blanket looked more interesting. Comparing the baking paper roll against the clingfilm, I shall have to weigh concerns about their relative biodegradabilty against my preference for sharp results.

Anyone got a great idea for recycling steamed clingfilm?


  1. only as a temporary playball for the cat:( but the bottom print really looks very beautiful! I was in doubt about using clingfilm in the microwave or for steaming for a good while, but eventually I decided that if I don't start eating my yarns I should be save:) wouldn't use it on foodstuff though - the thought about what toxic stuff might end up in my food from the heated plastic gives me the shivers:(
    btw, I was part of the acerbic dye discussion on FB last night (gerri guinness)- enjoyed it myself, too:) I thought we'll get into trouble soon, but nobody commented about having to be nice in the group!:)
    hope your teeth will recover with this lovely print - even without berries;)

  2. I might have guessed :) Gumshield in place before opening pinterest these days. I have come to suspect that the more fanciful the handle, the less credence I should place in the comments in the natural dye group - 'Ann Jones' has probably been working with a plant for years, 'Ermine Verminjersey de la Bilberry' has probably got a crush on someone who looks boho and knows her way round photoshop.

    1. most likely:) I have to admit that I tried the berries many years back as well - but I'd never write a book about that with fancy pix:( but after hearing from a well-known german dyer that she "had" to adapt some of the colours in her book to make them come "true" - I don't believe anything fancy in natural dyeing anymore anyway:( I don't expect my dyes to last centuries unchanged (if they did, why is the grass in old hangings always blue?:)- but they should at least survive the first wash? or maybe I am just not "artistic" enough?:)

  3. Thank you for this excellent post. I just bought some silk scarf blanks to try so the timing was great.

  4. You can use drop cloth plastic, which is a bit heavier than clingfilm, and can be re-used. I think I read about it here - .

    It makes sense, especially for standard sizes like scarf lengths, which are generally ~10" wide x ~72" long.

    1. Gosh thanks for that link - what an excellent explanation of the process - don't know whether to be gutted I didn't find it ages ago or pleased to have a plan to get some plastic drop cloth :)