Friday, 13 January 2017

Dyes from Brown Onion Skins on Wool, Silk and Cotton.

Many thanks to everyone who bought a Plant Dyes for All Seasons Calendar. Since the January project is dyeing with onion skins, I thought I had better have another go at it myself, just in case any customers emailed me to ask for advice. Since the New Year, every time I have passed the supermarket, I've bought one onion, stuffing into the bag with it all the other loose skins from the onion tray. The self service check out is a great way of avoiding curious questions. However, questions there are. A friend of mine started a 'Dyes for All 2017' discussion thread on the UK Spinners Group on Ravelry - here. The Ravelry website has free membership, do come and join the group, no calendar purchase necessary. Anyway, first I was anxious I might have to be the calendar thread's 'expert', then as people arrived, I was delighted to find I'd be learning stuff from other dyers.

Part of the onion skin dye project I wrote for January was intended to demonstrate that plant dyes are taken up differently by different fibres. This is a photo of the test run I did before writing the calendar, deep orange silk at the front, golden wool in the middle and more muted cotton at the back. They were all dyed together in one pot. I hadn't actually appreciated that these colour differences depend, at least in part, on the fact that each kind of fibre takes up the dye at a different rate. Light dawned when BatOutOfHell posted on the Dyes for All thread 'I have found out the hard way that if you put silk in a dyebath with other fibres, the silk is greedy and sucks up the dye quickly leaving less for the other fibres. Cotton on the other hand likes a long slow dye bath and “sips” up the dye slowly.'

When I read this, I had just simmered 66g of brown onion skins for an hour and left them to cool overnight. Next morning, after sieving out the skins by pouring the bath through a colander into a bucket, I found I had 8.5 litres of deep orange dye bath. Ready for dyeing, a total of 72g materials had been soaked overnight -  two small skeins of laceweight merino wool, a piece of cotton fabric and a much bigger tubular section of silk jersey. None of these needed any mordant, as onion is a substantive dye. Vexing myself with some maths, I calculated that a fair share of the dye bath for one of the 5g skeins of wool would be nearly 600ml.

Working in a kitchen with the door shut against freezing winds, it is very comforting to know your steaming dyebath is nontoxic. Onion skin soup is supposed to be superhealthy - unless you are a dog. What is more, cooking skins don't smell anything like as much as the layers of onion flesh inside would. Anyway, I had no worries about using one of my ordinary small saucepans for this experiment. 


Putting one skein in the small pan with 600ml of the dye bath, all the other materials went in the main pot together, to fight over the available dye. Though it doesn't show up well in photos, the separate skein definitely took on a deeper colour that the one that was in together with the silk. The difference was most obvious while the two skeins were wet.

This is an important factor to understand. As BatOutOfHell said, to make fair colour comparisons, each type of fibre needs to be dyed separately with the same ratio of of dye to its weight. While it was dyeing, I put a wire loop through the tubular piece of silk, hooked it onto the cooker hood and hitched the fabric out of the dye bath, bit by bit. There was already a peachy colour on the silk after five minutes warming, more fabric was pulled up at 20 and 40 minutes and more again when I turned the gas off at 60 minutes and left the bath to cool overnight. It does seem that whatever their depth, there is also a qualitative difference in the colours on the different fibres.



While this wasn't a controlled experiment on the speed of dye uptake, you can see by the gradations of colour on the silk that it really does pay to leave things to soak in the dye bath overnight. The last section is much deeper than any of the parts that came out of the dye bath before and up to the end of the heating process.

Though it wasn't part of the calendar project, I thought I'd also double check the effect of modifying the colours. Three more unmordanted merino wool laceweight 5g skeins were simmered for an hour in the onion afterbath. As the plain bottom skein shows, there was still plenty of colour in there. The middle skein was then modified by heating briefly with iron solution, which turned it deep green, just as expected. The top skein was modified with copper solution, which only dulled it down.

So far, so very satisfactory. I got onto Ravelry, posted some photos (with much relief that my dyeing had turned out well) and caught up with other conversations on the Dyes for All thread. Does it matter if you boil the dye bath? People thought not. Now I have read and believed from experience that some plant dyes will be ruined by overheating. In fact, on the January page, I wrote about the difference between simmering and boiling and specified simmering for this project, thinking it was a sound principle and good practice for any dyer. Before chipping in with an opinion, I decided to illustrate the point, pretty confident the following test would be a felted beige disaster. 

I weighed out 5g brown onion skins and boiled the life out of them for an hour. Next day I sieved out the flaccid skins, put in a 5g skein of merino and boiled that too. Imagine my shock at discovering firstly, the yarn was perfectly alright and secondly, the colour on it was gloriously rich. Boiling had practically cleared all the colour from the dyebath. Must be a mistake, probably my scales had been inaccurate - they aren't great at the level of one or two grams. I weighed out 50g of onion skins and boiled the lot. Made a 50g ball of white Rowan Pure Wool into a skein, gave it only a couple of hours to soak and then boiled it in the dye bath. In this picture, the original simmered skein is on the left, the boiled skeins are on the right, all three had a one to one weight ratio with onion skins and one hour heating. The only conclusion I can draw is that, as far as brown onion skins are concerned, boiling improves the uptake of dye - substantially.











So, back to the Dyes for All thread to eat humble pie. Reading through the calendar projects, wondering what other humiliations I had laid up for myself, cold horror swept through me when I got to the October project. Oak galls do dye wool pinkish, but they are used as a mordant for cotton and linen, not wool and silk, as I have written. I am very sorry to have misinformed people. I do hope your onion skin dyes come out well.


10 comments:

  1. I'm actually quite amazed at the depth of colour you got by boiling the onion skins. I've always just simmered them, getting good colour, but nothing like that. Wonder if it works for red onion skins as well. Should do - must try it.

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    1. I'm investigating red onions myself. I'd have guessed a red type of dye bath would have the more fragile type of dye molecules in it, but I am certainly not going to assume that til I've tried it :)

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  2. red onion skins always gave olive greens for me, esp. on light grey fibres. and I wouldn't call onion skins substantive - because the lightfastness improves a lot with a mordant (which wouldn't be the case with true substantive dyes). also I always let the dyed skeins/fabrics dry without rinsing. if you leave the rinsing for a week or two, it'll improve fastness as well. and if you dye consecutive batches in your onion "vat", you'll get all colours of yellow, from dark orange, nearly brown - to very light "icy" yellow! if you add iron to those lighter yellows you'll end up with gorgeous green tones that work perfectly with the yellows... I've done a lot of onion skin dyeing about a decade ago - still have some of the skeins in my stash:)the only thing I didn't manage - to make a ratio of 1:1 - with 500 to 800 g of WOF, there was no way to find a pot that's large enough for that amount of dry skins:) didn't matter though, I still got strong colours.

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  3. I had read that an alum mordant improved light fastness, but the trial skeins I dyed last autumn haven't had enough sun through the winter to fade yet. Good to know it is worth mordanting, before I dye for a proper project. I am saving up onion skins again, I really fancy that plan for a proper sequence of dyes and iron mordants.

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  4. what a glorious range of colours!

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  5. A friend in Germany uses a dedicated 'coffee' urn for her onion skin dying. She 'percolates' the skins and wool together. I think you could 'cook' the skins and then pour off the liquid via the tap. Helen

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    1. It's such a good dye, I can see how handy it would be to have it 'on tap'. Interesting idea.

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  6. I think my comment disappeared (or I'm not patient enough) . Basically it was saying that I thought the calendar was about 'how to start dyeing now, without months of research' or One Smart Lady writes all the hocus pocus spells you need to make yarn change colour! Now with added Starlet on back page! If you wanted to you could put an Errata sticker on anynew calendars. Also I'm test knitting at the mo. Maybe someone wants to test calendarer er next time? Thanks for caring about us x

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    1. You are quite right about the calendar's intention, though I can't help feeling more research by the author would have been wise. I just go head first into things that seem like a good idea. I appreciate your offer to be test pilot :)

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