Natural

“Western consumers have become more concerned about the health and environmental impact of synthetic dyes—which require the use of toxic fossil fuel byproducts for their production—in manufacturing and there is a growing demand for products that use natural dyes.” - Wikipedia

Natural dyes are dyes made from naturally-occurring materials - overwhelmingly from plants, but also from minerals, insects and even shellfish. Dyes are soluble and they change the colour of the material they come into contact with, whereas pigments are non-soluble, requiring a binder to hold the colour on the surface of a material.

There are chemicals in nature that produce colours. In plants, those chemicals might be in the leaves (e.g. weld: yellow/orange); roots (madder: red/deep pink); bark (soaked birch bark: pink/brown); flowers (marigold: yellow/orange; dyer's chamomile: yellow/gold); or even stamens (saffron: golden yellow). Most dye plants grown in temperate regions produce gentle colours in the yellow/orange/pale green/beige range, but tropical dye plants can give bright, deep reds, purples and blues. Indigo is a tropical shrub and a source of blue. It is difficult to grow in temperate regions, where blue has traditionally been provided by another plant - woad.

Dyes from rocks and minerals include ochre (oxide-containing clays) for yellow, brown or red; limestone or lime for white; manganese for black; cinnabar (mercury ore) for red; and malachite for green. Rust (iron oxide) can also be considered a mineral dye - which gives, not surprisingly, a yellow-orange-brown colour.

Then there are dyes from animals - brilliant red from insects such as kermes (Europe), cochineal (Americas) or lac (Asia); and royal purple from shellfish of the murex genus.

People like colour, and so when creamy/grey woollen or linen products were first made, there would only have been natural materials to colour them. It's thought that dyes developed from the use of medicinal plants, when it was discovered that they produced colours ('tincture' and 'tint' have the same latin root). Bright colours were difficult to obtain before the industrial revolution, and the rarest dyes were status symbols. Indigo dyeing used to be banned in the UK because it was feared that it would put woad dyers out of business. Woad was an important part of the economy - the city of Toulouse was built on the wealth from the woad industry. However, woad dye manufacture historically involved stale urine and wood ash, prompting Elizabeth I to ban woad dyers from working within 5 miles of her royal palaces. Royalty got their purple robes from dyes from the murex shellfish, which were rare and expensive. Commoners were forbidden to wear purple on pain of death. Lady's bedstraw, a plant in the madder family, grows on sand dunes in Scotland. At one point, Scots were picking so much of it (for red dye) that the dunes were eroding. Picking it became a crime punishable by death. Wild Colour by Jenny Dean contains more information on dyeing history.

Natural dyes need to be used with mordants (from the latin mordere - to bite). They are substances that allow the plant dyes to 'bite' onto the fabric, making it set, and stopping it from washing out. Examples of mordants are aluminium sulphate (alum), copper sulphate (Bordeaux mixture, which organic gardeners use against blight), tannic acid (from oak bark and leaves) and oxalic acid (from rhubarb leaves). 'Substantive' dyes don't need mordants, because they're from plants that contain natural mordants - for example pomegranate skin, which contains tannic acid, and is used a lot in India to produce yellows and browns.

Natural dyes can provide colour from local, natural, organic materials. The cheapest and most environmentally-friendly way of dyeing is by growing or collecting local, native dye plants and dyeing fabrics yourself. It's very exciting to see colours appearing in items you've made yourself, from plants you've grown yourself.

Another benefit is the quality of the colour produced. This may be subjective of course (the beauty of a colour isn't scientifically measurable, so how many opinions do you need before something becomes objective?), but natural dyes tend to produce more beautiful colours. Synthetic colours can look stark and, well, too synthetic. A traditional Persian carpet will always look more beautiful than a modern synthetic carpet (don't you think?).

When it comes to evaluating the environmental benefits of natural dyes over synthetic dyes, it's tricky. Certainly the synthetic dye industry is one of the world's most polluting industries. Most garment manufacture nowadays takes place in countries where environmental law is weak or largely unenforceable, and so waste water and sludge laced with toxic chemicals is routinely released into watercourses and onto land. Over 50,000 tonnes of synthetic dyes containing heavy metals, benzene and formaldehyde and 200,000 tonnes of salt are released into watercourses globally each year by the dyeing industry. See here for more information. Natural dyes by definition can be re-absorbed by nature.

However, natural dyes require more water and heat per area dyed than synthetic dyes, and if the world switched from synthetic dyes to natural dyes tomorrow, to dye the same amount of material, we'd have to use way, way more agricultural land to do it. The human population is too large, and we want too many things, to be able to provide for ourselves from natural sources, and so we have to use environmentally-damaging procedures and materials. Perhaps at some point we'll realise that not everything needs to be dyed, we shouldn't have new fashions every year, and we can't have growth in our population or our economy forever. In the meantime we're not advocating large-scale industry, we're advocating, as with most of our topics, small-scale craft production, with plants from the wild and from gardens.

You can find various natural dye suppliers online, but it's much cheaper to grow and make them yourself. A course might be a good idea. You'll need scales, a stove, some big pots and a recipe book, unless you just want to experiment and see what happens. Simmer with a mordant first, then in the dye pot until you have the colour you want. If the colour isn't strong enough, add more dye material.

You're not just looking for strong, beautiful colours, but also colours that won't fade. Light fastness is important. For example, beetroot will dye something quickly, but it will fade quickly too. So it's important to choose good dyeing species for fastness and the colour you want, and to use a mordant bath to prepare the material before dyeing. Copper, chrome and other metal-based mordants are quite toxic, and any waste has to be dealt with in council facilities - so use alum, or boil up rhubarb leaves for oxalic acid, or oak bark and leaves for tannic acid, then drain and keep in containers in a cool shed until you need it. Weigh out your alum precisely (home-made mordants will be more hit-and-miss - but you can experiment), according to the weight of material you have. It's a slightly different mordanting process for plant fabrics than for wool - the mordant is mixed with washing soda. You can find fleece recipes in various books.

Here are some temperate dye plants that you can grow, for:

• yellows or oranges - onion (skin); coreopsis (flowers)
• lemon yellow - weld (leaves and flower stalks)
• greeny yellow - dyer's greenweed (leaves); tansy (leaves and flowers); foxglove (flower spikes)
• pinky yellows or reds - St. John's wort (flowers)
• reds - madder (roots); safflower (flowers)
• purply maroon - elderberries, but it fades fast - in fact all colours from berries fade fast
• blue - woad, a biennial plant, can give a beautiful, pale, translucent blue; use the first year's leaves - harvest after a few days' warm sunshine
• green - it's hard to get a good green from plant dyes, surprisingly. It's easier to dye something yellow, then dip it into blue. For example, Lincoln green (think Robin Hood) was made using weld overdyed with woad

As well as growing your own dye plants, you can collect natural dye plant materials from the wild. Birch bark can produce pink-brown colours, and walnut leaves give brown (the kind of brown depends on which mordant is used, but they can also dye without mordant).

You can dye plant (i.e. not woollen) fabrics with rust. Leave the cloth in a rusty bath for 30 mintues, then quickly dip it into a bath of water mixed with a small amount of caustic soda or tannic acid (wear gloves when using caustic soda) to set it. You can make your own tannic acid bath by soaking oak bark, leaves or galls. With a tannic acid bath, you can achieve a deep brown-charcoal colour.

Thanks to Jane Meredith of Plant Dyed Wool for information.

Janet Renouf-Miller runs Create with Fibre, and is a registered teacher with the Association of Weavers Spinners and Dyers and has taught at their renowned Summer School. Janet has also taught courses for many spinning and weaving guilds, knitting groups, shops and voluntary organisations. She is the author of How to Spin (just about anything).

Date on Lowimpact:2013-04-17