Tuesday, 21 March 2017

Know your onions

For me, the principle attraction of natural dyeing and eco-printing is the unpredictability of the results. Take the humble onion, the red variety in this case. Skins are widely and freely available. Go wherever they are sold and ask to root through the box for the loose skins. In no time at all, you will have a bag full, for free. The shopkeeper will probably even by grateful that you have tidied them away. Take them home, put them in a pan with some water, bring up to simmer for an hour or so and the water turns a wonderful ruby red.

Red onion skins simmering in a slow cooker

I do not claim to be an expert, I have been playing with natural dyeing for a little over a year so I am still very much a novice. I read a lot, research, follow other natural and eco dyers on social media but above all, I experiment. I did some dyeing with onion skins right at the beginning of my natural dyeing career early last year and unsurprisingly, I got a reddish brown colour from red onion and a golden brown colour from brown onions on silk habotai and noil. (Silk habotai is a fine silk and is what most people think of as 'silk' whereas noil is a coarse, slubby fabric woven from the shorter fibres left after the longer fibres have been removed to make the fine silk. I discovered silk noil in a sample pack I bought to try different kinds and loved it. It is reminiscent of linen but is great for natural dyeing as it is a protein fibre. Protein or 'animal' fibres such as silk and wool take natural dyes in general without the need for an additive or 'mordant'. Cellulose or plant-based fibres such as cotton, linen or hemp in general do need a mordant such as soy or alum to enable the dye to 'bite' into the fabric and be fixed. But as I said, I am no expert and I would refer you to Wild Colours UK or the Maiwa website for comprehensive information).

Anyway, huge digression, back to the matter in hand, my onion dyed and printed silk, gold and reddish brown colours, as you would expect. Silk noil on the left. habotai on the right.

After that I became so wrapped up (pun intended!) in eco printing that I left the humble onion skin behind, except for occasionally throwing a few torn up bits of skin into a bundle to enhance the leaf prints.

Then a few weeks ago, I went to visit a friend who has also recently been seduced by natural dyeing and she was showing me her collection of natural dyed samples. She is aiming to dye a range of greens and browns for a series of landscape inspired work and I was particularly struck by a little stack of olive green cotton and linen pieces. They had been mordanted in alum then dyed in red onion. No other additives. So I went home, went foraging in my local supermarket and set to. I alum mordanted some linen and cotton scraps. I simmered my onions to extract the dye. I added my pre-mordanted cloth as well as some noil and some old wool blanket.

 And I got shades of reddish brown on the linen and cotton. Nice enough but not the olive green I was hoping for.

 On the unmordanted silk noil, habotai and wool, I got a beautiful shade of gold - old gold or antique gold I would call it. The top is the wool followed by noil then habotai. All the reddish brown pieces are the various cotton, linen and hemp scraps, all pre-mordanted with alum.

So I messaged my friend, perhaps she had added iron or something else to the dye bath? No she hadn't. So I did some research and read that the chemicals in onion skins are very complex and can yield all colours from dark red through browns, oranges and terracottas to golds and the elusive olive green. What colours they decide to give you and when depends on a whole range of factors, relating to the onions themselves such as how and where they were grown, and lots of other factors depending on your dyeing conditions, acidity or alkalinity of the water, temperature and duration of simmering and so on. Fascinating, I hope you will agree. I read a paper by Jenny Dean which seemed to suggest that alkalinity would more likely result in greens.

So yesterday, I went back to the same supermarket and tidied up the red onion basket for them again. (They love me!) I had some left over alum mordanted cotton sheet and also some noil and some old wool blanket so I repeated the exercise. Only this time, I ground up a few indigestion tablets (calcium carbonate = alkali) in my pestle and mortar and added them to the dye bath. I had read somewhere (not sure where) that doing this, the dye bath turned green before your eyes. Mine stayed defiantly red.  A very experienced natural dyer had told me on Instagram that adding iron to the dye bath gave olive green. Now I know this isn't how my friend got that colour. But I wanted insurance. So I divided my dye bath in two pans and to one half, I added a good slosh (natural dyer's standard measure) of my 'clean' iron water. I have two kinds of iron water. The 'dirty' kind is simply rusty rain water bailed out of one of the buckets in the garden that house my rust collection (such as the one in my previous post). The 'clean' kind is made by putting a fist sized piece of steel wool into a large jar and topping up with a third white vinegar to two thirds water (ish). When the liquid turns brown it is iron water. Here are the two pans.

This is the un-ironed one, as you can see, it's reddish brown. The length of white stick has some alum mordanted cotton thread wrapped round it.

The ironed one - much more promising, though at this stage it looked almost black and I was wondering if I had overdone my slosh of iron water. It has that lovely iron bloom on the top of it.

So I simmered both for around an hour I think. I am not very accurate in my time keeping but it was about that. Usually, I would leave dyebaths to cool overnight but I couldn't wait, so I fished the cloths out with tongs into the sink until they were cool enough to touch then I squeezed the excess dye back into the pots. I did the unironed cloths first, then the ironed ones.

The unironed ones were much the same colours as my previous efforts without the indigestion tablets, except the gold on the wool and silk is darker. I also got a lovely gold on a piece of alum mordanted cotton sheet.

From top to bottom: this time's cotton sheet, last time's noil, last time's habotai, last time's wool blanket, this time's wool blanket.

I didn't take a photo of the other pieces but they were all that same reddish brown in various shades. When I squeezed out the ironed cloths, I could see straight away that I had olive green. Yeaayyy! So I mixed both left over dye baths together and chucked in all the disappointing reddish brown cloths and simmered them for another half hour. I know! Reasonably sccientific up to that point (well, perhaps not!) and at the end, I revert to type, mix things up and chuck things in. But..... look at all the lovely olive greens! The darker pieces are from the first ironed dye bath and the lighter pieces are from the 'chucking it in' stage of the proceedings. I also chucked in some other scraps that were hanging about, the bottom two scraps are bits of flannel that had been tea dyed but not mordanted with alum (as far as I remember). I love doing this, especially with repurposed cloth because I often get lovely marks appearing as you can see here. I also deliberately don't spin my mordanted cloth or rinse it very thoroughly or wring it out properly because I actually prefer patchy results. Neither do I scour anything which means prewashing it on hot in a special detergent to ensure even take up of the dye. I like things uneven. And I don't like to use lots of heat and water if I don't have to.

Green from red - finally! With the help of a little iron.
So in conclusion, do I know my onions? Hardly! But I got the results I wanted in the end, just not by the means I planned. And that's why natural dyeing fascinates me. My next plan is to go to my friend's house and try again there, using her water and the onion skins from her supermarket. It can never be a completely controlled scientific process as there are way too many variables, but it's a lot of fun!


  1. Fascinating, green is usually so hard to get and surprising you got green from iron as I would have expected copper to work better. Perhaps its a reaction between the alum and the iron?
    I must give this a go, thanks for sharing

    1. Hi Debbie, yes usually copper greens things up and iron saddens doesn't it? Perhaps next time, I will see what copper does! I don't think it is alum/iron as some of the scraps were only tea dyed, no alum. Unless the alum and tannin react in a similar way with the iron, both being acid. 😊 xx

  2. Your experiment is fascinating. I love using onion skins, especially on wool and linen. I am experimenting with using rosemary for a very pretty sage green on silk. It's relatively pale on unmordanted silks, but I'm liking the subtlety. Wormwood gives a nice olive green so I want to start growing some :)

    1. I have seen the green you describe from rosemary and agree that it is beautiful. Interesting about the wormwood, I will look into that, thank you. :-) xx

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