Based on their origin, natural dyes are classified into 3 categories:
- vegetable origin
- animal origin
- mineral origin
The most common of the three are vegetable-origin dyes which are extracted from plants (flowers, seeds, roots, skin, etc.). The red color can be extracted from madder and brazilwood, blue color from indigo, and flowers of Japanese Tsuykusa, yellow color from barberry, Kamala, turmeric, and marigold. The green color is normally got by mixing yellow and blue colors since the green primary color is very rare. The same goes for the orange color where red and yellow primary colors are mixed. For black and brown color, also animal and mineral-based dye origins are used: cutch, carbon, and lac insect.
Other animal-origin dyes can be derived from cochineal insect (red), cow urine (Indian yellow), murex snail (purple), and octopus/cuttlefish (sepia brown).
The mineral dyes are extracted from different mineral ores, red clay, ball clay, etc.
The examples above are not exhaustive, but give you an idea what are the main sources of natural textile dyes.
The positives
- No health hazard
Now, this can be argued, as below we will mention that different toxic mordants are being used to fix the natural colors to different fabrics. However, compared to industrial dyes, the natural dyeing process is definitely less harmful to the environment and people’s health.
- Easy extraction and purification
Since they are chosen from nontoxic sources, they can be handled very easily and safely compared to industrial dyes. Some examples of different extraction methods are aqueous extraction, acid and alkali extraction, ultrasonic microwave extraction, fermentation, and solvent extraction.
- No effluent generation
This applies only in case no toxic mordants or fixatives were used during the dyeing process. This, unfortunately, is rare as most of the natural dyes need mordant treatment.
- More sustainable
The waste of synthetic dyes from the textile industry causes environmental problems due to the many chemicals used in the dyeing process. The use of natural dyes is considered less harmful as it produces fewer pollutants. The main challenge is to find mordant-like materials that would be environment-friendly.
- Renewable sources
As mentioned above, natural dyes are of vegetable-, animal- and mineral origin and the majority of them are extracted from plants. Therefore the source can be considered renewable.
- Boosting rural economy
Natural and vegetable dye material cultivation, collection, processing, dye extraction, and dyeing of textiles are considered to be agro-based rural industries, which helps to promote rural entrepreneurship and thus developing the rural economy.
The negatives
- Extremely costly
Natural dyes are not nearly as accessible as artificial dyes and prove to require a lot more time, effort, and materials to produce. Some research work should be done to reduce the cost of production.
- Poor reproducibility of shades
While there is a great variety of shades that can be extracted from natural dye origins, it is much less compared to synthetic dyes and there is also no shade card to match the samples or reproducing the shades.
- Poor colorfastness
The color from natural dyes fades over time and is not as resistant as synthetic dyes. It means they lack dye compounds that have the necessary molecular structure to form stable chemical bonds with mordants and fibers and are therefore not very resistant to fading when washed, exposed to light, or subjected to normal rubbing/abrasion.
- Poor bonding
Overlaps with the previous topic. Mordants and fixatives are often needed to compensate for the lack of molecular structure to fix a dye to the textile.
- Mostly applicable to natural fibers
The natural dyes work best with natural fibers such as wool and silk. Wool and silk are both protein-based fibers that have better bonding structures and therefore work the best. Cellulosic fibers are difficult to dye with natural dyes as they have poor affinity and substantivity. However, with the help of mordants, it is still possible and practiced. Natural dyes can also be used for polyester which is not a natural fiber.
- No standard color recipes and methods available
After industrial dyeing came along, the knowledge and techniques used for natural dyeing were slowly fading. It means the techniques and knowledge used nowadays are fragmented and not unified across the natural dyeing industry. As mentioned earlier, there is also no shade card to match the samples or reproducing the shades.
- Uses metallic mordants, many of which are not eco-friendly
Due to poor bonding, different mordants and fixatives are used to fix the dyestuff to a textile. Alum (aluminum ammonium sulfate) is the most known and widely used mordant, but also iron, copper, tin, and chrome. The most known fixatives used mainly for cellulosic fibers are salt, tannin, vinegar, and baking soda.
Undyed fabrics
If after reading the post about industrial dyes and natural dyes you realize that none of them is really 100% natural, you do not have to lose hope as there are also undyed fabrics and ready-made clothes available. If you are into sewing yourself or know a person who can make you a great piece of clothing, you can buy the undyed fabric from Etsy or even from Amazon. If that is too much of a hassle, you can find ready-made undyed and naturally dyed products by the following providers: Industry of All Nations, Housework, SeamsFriendly, Harvest & Mill, and Indigenous. If you do your own research, I am sure you are able to find much more providers.
Conclusions
I have to admit I was rather enthusiastic about natural dyes before looking further into the topic. The more you read and learn about natural dyes and the dyeing process, you realize there is still a long way to go before natural dyes could be widely used and actually called sustainable and eco-friendly. India seems to be the country ahead of others when it comes to the natural dyeing industry and the different methods and techniques used in the dyeing process.
The main issues that are partly mentioned in this article already are the lack of knowledge and unified dyeing methods to be able to use natural dyes more widely, the need for a lot of natural resources in case natural dyes would be used for mass production, the need to develop non-toxic mordants and fixatives to better fix the dyestuff to a textile and improve colorfastness, proper classification of different shades and the unified guidelines about how to reproduce certain shades, better techniques and methods to reduce water usage and/or recycling of water.
While natural dyes are better compared to industrial dyes, their usage similarly needs improvement and more research has to be done to reduce the negative aspects mentioned in this article.