Are natural dyes sustainable?

Natural dyes – another buzz term in the sustainable world and I’m starting to see it become more popular in the sewing world. Being sucked in by pretty pictures of Instagram feeds of popular natural dye bloggers and the experience of some of my sewing friends, I thought to do some experiments myself. But before that comes the research on the how-to, and I’m afraid that my conclusion is that natural dyeing is not an activity to be done on a regular basis in the name of sustainability.

Let’s dig in. Marketing can make anything look sexy and here’s the kind of pretty picture that sucked me in. I remembered my friend Pilar bought this book awhile ago, and in the interest of immediate reading I bought the ebook by the same author. From there, I moved on to less sexy looking natural dye webshops and websites, googling chemical names, and speaking to my chemical engineer friend.

What is a “natural dye” anyway?

The “natural” in the term “natural dye” typically refers to the materials that do the dyeing – i.e. plants, as opposed to the unpronounceable synthetic chemicals you’d see in a Dylon dye for example.

Why natural? Well, it feels good to be using plants in your (or someone else’s) garden and things from food waste. Also, it’s unlikely to kill you. I’m referring to avocado skins/stones, pomegranate skins, onions, lavender etc. in terms of things that are generally accessible in daily life. Of course there are loads of other plants and trees used for dyeing which aren’t found in the average European garden (indigo for example) – humans have been using plant-based dye for thousands of years. A lot of these are available in extract form (powder) from webshops.

Anyway the point here is that I’d beware that the term natural automatically means good, even though a lot of us have been conditioned to subconsciously believe that. Every website recommends you wear gloves during your natural dyeing activities. And let’s not forget that not all plants and natural stuff are good guys, there is plenty of toxic stuff as well (arsenic anyone?)

Natural dyeing is still dyeing

…And still consumes resources. For home dyeing, the sustainability point feels just as bad to me regardless of whether you are using natural or synthetic. But “sustainable” is really your interpretation. If you dye something to a colour you like and then wear it to death, that might be more sustainable than buying something new. You decide.

My synthetic dyeing experience

Dylon home dye for me has been effective. In summer 2018 I dyed the above blue linen dress and since then it been washed SO many times – without any colour fade. Unlike the original navy of the linen which faded to the point of looking really old within a few months (thus prompting the dye experiment). Note this was also Merchant and Mills linen which is not cheap! I remembered just before the dye exercise to take an un-pretty before picture with my phone. You can see the fade lines after not a lot of wash/iron/wear.

What didn’t feel good was that it did require me to buy 500g of salt to go with the dye. That’s 4 small supermarket shakers of salt for 1 piece of fabric. And all of the salt went down the drain. Not to mention the water to rinse off the excess dye particles.

The next time I dyed something was with a Dylon pod which went in the washing machine, and I made some black faded clothing “intense black” again. Like the hand dye, it worked great. I don’t know how much water the machine uses vs what I used for the hand dye. But I did have to run another full machine cycle afterwards, and scrub the seals which were stained with black.

How to use natural dye

Natural dyeing at home is much more a faff than something like Dylon. You still need to use water, and in many cases, a synthetic chemical boost is needed depending on the choice of plants. Additionally, there’s often talk of different techniques to avoid colour fade and needing to take special care post-dyeing. Here’s the basic dye process.

1. Clean fabric – using a regular washing machine cycle, or soaking with soda ash (sodium carbonate).
2. Pre-treat fabric – if needed, soak it in a chemical solution or soy milk to make the fabric absorb the dyestuff better and “fix” the colour (more on this below). After soaking, the excess moisture then needs to be spun out in a washing machine, or fabric might need washing again depending on what you used to soak.
3. Dye fabric – in a pot with water and choice of dyestuffs, and apply heat. Once dyed, rinse again.

Chemical use in natural dyes

Chemical is a word you’ll never see used in marketing. With natural dyeing, step 2 above on pre-treating fabric is referred to as “mordanting”. I’ve used the term pre-treatment because whilst it’s common to call soy milk a mordant, experts like guru Jenny Dean will say it is isn’t a “true” mordant as the soy doesn’t form a chemical bond. Rather, the soy milk might be a good sizing agent to help absorption. This is an important differentiator because it’s about how well the dye will “stick” to your cloth and what colours you get. You can see on Jenny’s website how the effects of the dye differ depending on mordant choice.

Update 20/1/2020 – an Instagram commenter was unhappy that I wasn’t explicit enough in stating that not all dyes need a mordant. For absolute clarity, the way I understand it is that there the use of mordants/pre-treatment depends on the fibre type and the dye. Soy milk is often used for cellulosics as a natural alternative to alum, whereas protein fibres might not need a mordant at all. But is it better from a sustainability perspective to be making or buying soy milk, compared to using a few grams of powdered alum? I wouldn’t know, though I suspect it’s a bit like baking a cake. To have aeration, you could use baking powder, bi-carb, whipped eggwhites, a combination of stuff. There are many ways to yield a similar result, you decide what works best for you.

Common mordants are metallic salts of chromium, tin, iron, copper, and aluminium. Chromium and copper were common as well but usage “has declined due to toxicology concerns” according to this article. One of the most popular mordants you’ll see is potassium aluminium sulfate. Because my eyes glaze over when I look at chemical names (I barely passed chemistry in high school), I asked my chemical engineer friend about it. He checked the Material Safety Data Sheet which said this is a stable and non-flammable chemical, but still requires protective gloves when handheld. Kind of kills the flowers and butterfly vibes evoked by the term “natural dye”, no?

So are natural dyes sustainable or not?

On a home level, I’d say to do natural dyeing for the fun of it – not because you want to be sustainable. Besides time, you need a lot of water and energy with the soaking, rinsing, washing, heating on the hob, and use of your washing machine. And as someone who grew up drinking soy milk, it seems like a bit of a waste to be buying or making it for the purposes of soaking fabric, and then chucking it out.

A former fashion lecturer of mine said if you really want to be sustainable with any kind of dyeing then bag up 10m of fabric and send it to a dye house – at least they have the proper infrastructure for disposing of wastewater etc. from a dye bath.

She also told me that on a commercial level, you don’t see natural dyes much. If you’ve gotten this far in the post, you can already see why, right? 1) Synthetic dyes perform more predictably than natural ones. 2) Fashion in general has a very high demand for colouration of textiles. 3) Finally, is growing plants for dyeing purposes really a good use of resources?

Leave it to you to consider. I’m actually going to a natural dye workshop to find out more about the process and ask questions, so if my views on this change, I’ll update this post. And of course I’ll write another post covering the workshop!

Till next time,
Kate

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