Natural Vs Synthetic Dyes: Which is better?
Written by Gabi Goddard.
Image by ethical, plant dye brand Indigo Luna.
For all the dye-curious out there, we’ve put together a guide for understanding the history, process, and problems associated with the part of the supply chain that gives your garments and textiles their colour.
It will come as no surprise that forms of dyeing fabrics have existed for thousands of years. You probably learnt about some type of ancient civilisation using dyes from plants or insects in primary school. Maybe you can even name one or more of those civilisations and their techniques.
While there are many natural dyes, here are the four with the longest textile histories:
- Indigo, which is most commonly made from the indigo and woad plants (although most indigo dye on the market today is synthetic—we’ll get to that!) It’s a blue dye, and a good colour guide is to imagine a pair of classic denim jeans—any shade, light to dark, can be achieved. The earliest example of indigo being used as a fabric dye was found in a 6000-year-old piece of cotton discovered in pre-hispanic Peru. Prior to that, ancient Egyptian remnants of indigo-dyed fabric were the earliest examples we had of indigo’s use as a textile colouring agent.
- Madder, which makes all shades of brick orange, red, gold and burgundy, is made from the roots of ‘madder’ plants (again, there’s also a synthetic version). Honestly, they look like weeds, but if you’re interested in dyeing your own yarn it sounds reasonably simple to grow. Madder was used to dye fabric by the ancient Egyptians, Greeks and Romans, and examples of those textiles have been uncovered in the tomb of Pharaoh Tutankhamun, as well as in the ruins of Pompeii and ancient Corinth.
- Tyrian purple. If you had any kind of Christian upbringing, you may know this as the colour of the dye Julius Caesar and his household wore (it was illegal but, regardless, prohibitively expensive for anyone else to wear it). In the bible, a robe dyed with Tyrian purple was used to mock Jesus. Tyrian purple is named for the ancient Phoenician city ‘Tyre’, where most of the dye was produced. It came from a species of sea snail, and needless to say, it was such a faff to get a hold of that it was as expensive as gold. Thankfully, in recent years we’ve learnt the same colour can be achieved from hibiscus!
- Cochineal/carmine creates reds and pinks, and is made from the cochineal insect. They’re tiny little critters that live on prickly pear cacti, primarily. The females eat the cacti berries which turn them red. It takes 70,000 (!!) insects to create about 450g of dye. If you, like us, loved your horrible histories chapter books as a kid, you’ll be interested to know that it was first the ancient Mayans and Aztecs who used cochineal dye. Like Tyrian purple, it was as valuable as gold.
Of course, not many of the garments in your wardrobe will have been dyed with insects, because it’s so much more economical to colour garments with synthetic dyes. William Perkin is the teenager to thank for their discovery. In 1856 WoW hadn’t been invented yet, so Will was trying to make quinine in his home lab and ended up creating a mauve dye instead. In 1856, he patented the dye and named it ‘Tyrian purple’ to make it seem fancier. But it was made out of coal tar—not fancy—and it started a whole industry of coal tar dyes, which continues to this day. Obviously back then, our mate Will didn’t have any idea that there was any problem with fossil fuels. His discovery was revolutionary and opened up huge ranges of bright colours that would easily cling to yarn and never fade.
The process for dyeing yarn both with synthetic and natural dyes is similar. Either way, you have to create a ‘dye bath’. This is a solution of water and the synthetic dye, or water, the natural dye/plant/root, and something called ‘mordant’. Mordant is a colour fixative, and assures that the natural dye adheres well to the yarn or fabric even when repeatedly washed.
Your yarn will go into the dye bath and soak up the colour. Eventually, the dye bath will be ‘exhausted’, which means as much colour as can be sucked up by the textile has been sucked up, and you now need to discard the contents of the dye bath.
That newly coloured yarn is woven into fabric.
For printed fabrics, cloth is prepared by brushing or ‘shearing’ (like a cross between shaving and epilating) the fabric to create a perfectly smooth surface. It is then stretched and straightened and mounted on a printing machine.
The dye, in the case of printing, must be thickened so that it ‘stays within the lines’ and doesn’t run when it’s transferred onto the fabric. We’ve looked into all the most commonly used thickeners, and they all appear to be benign.
When using natural dyes, mordant must be either mixed into the dye, or placed onto the fabric in the final pattern, for the thickened dye to stick.
Are synthetic or natural dyes problematic in any way?
One of the arguments we’ve heard in defence of synthetic dyes is that natural dyes require mordant to fix colour to fibre. Mordants can be toxic, and therefore, the argument goes, they are no better than chemical dyes at all.
Historically, it was common for mordants to be made out of toxic heavy metals like tin and chromium. Nowadays, the most common mordant is ‘alum’, which is also used in food and body products. ‘Think Dirty’ app rated alum in deodorant as a 4/10 toxicity, putting it in the green (or ‘safe’) category for long term skin exposure. Copper and iron can also be used. These might not sound safe, but a common way to transfer mordant to fibre is to soak old nails or copper pennies in the dye bath—completely harmless. Dangerous concentrations of these metals/metal salts are not required.
So, what about chemical dyes? Contrary to what dye manufacturers will lead you to believe, chemical dyes require metal salts too, they just create a blend of dye and mordant and you buy the colour as one product. More disconcertingly, they’re not required to disclose their blends, but cadmium, lead, chromium and tin are all found in chemical dyes.
Unsurprisingly, this makes chemical dyes terrible for the dyer, wearer, and the environment. In humans, chemical dyes can severely damage the mucous membranes of the human body as well as its organs. This is not uncommon amongst textile workers.
If a low-tox home environment is important to you, avoid wearing clothing dyed with chemical dyes, as over time it is absorbed by the skin in tiny amounts.
If sustainability is important to you, then you should be aware of the fact that with each wash cycle, a small amount of dye is released into the earth’s waterways. Don’t beat yourself up though—it’s very difficult to avoid chemical dyes, especially if ethical-clothes-shopping for you looks like buying secondhand clothes, rather than from sustainable brands. Our world simply hasn’t shifted its value system enough to place the natural world at the forefront yet.
When it comes to synthetic dying, the biggest problem for the environment (by far) is the manufacturing process of the dyes and the fabrics. As we mentioned, synthetic dyes are cracked from crude oil, which means there will always be carbon emissions. But most terrifying is the disposal process. In all cases, the dye baths must be discarded. And, as we know, the largest manufacturers of clothing worldwide exist in the developing world, where systems are not in place to regulate the safe disposal of toxic waste-water. The dye-baths end up in the rivers, and those rivers carry the crude-oil based colourants and heavy metals throughout the natural world.
This is depressing. Please tell me there’s a solution?
The problem lies in our capitalist society. The easiest way to keep up a pattern of continuous financial growth is to use the cheapest, easiest dyeing method. It takes careful planning and more money to manufacture natural dye in a commercially viable way (but it is absolutely possible).
It also requires more resources in terms of land and water—you need plenty of both to grow the plants to make the dye. This is completely prohibitive to the rampant commercialism that forms a core part of our current world’s value system. If we continued to manufacture clothes at the same rate but with natural dyes exclusively, then unquestionably we would not have the resources to dye all garments.
It has been suggested that the solution lies in a synthetic-natural dye hybrid, perhaps GMO plants to create dye with.
But here at EME, we argue that the solution is glaringly obvious; we need to slow down our consumption. The global North needs a complete revamp of its value system. Imagine a world where people bought only what they needed, because the concern for this beautiful unearned planet was primary.