What would be the most environmentally friendly way of dyeing textiles? As a retailer of organic cotton t-shirts, I am naturally concerned about this.
It would sound right to say that the most environmentally friendly way of dyeing textiles is one which no chemicals, especially toxic ones are used in the process. However, when placed alongside other considerations such as energy efficiency, labour resources and sustainability, the “right” answer is quite difficult to conclude.
These are my attempts to work out the differences:
1. Naturally-Coloured Cotton
Sure, it is great to know that there are naturally coloured cotton developed like what Fox Fibre® did. However, consumers yearning for more varied and vibrant colours in organic cotton fabrics has prompted the textile industry to source for alternative ways to dye textiles in a responsible and sustainable manner.
- The most environmentally friendly – no chemicals and metals!
- Fewer variety of colours
2. Natural Dyes
Natural dyes can come from plants, insects or minerals such as clay, though for minerals, pigmenting is a more accurate term than clay-dyeing.
2.1. Ayurvedic clothing (Ayurvastra)
I have been researching on eco dyes to use on textiles and even had the chance to pay a visit to a couple of garment makers in India which dye textiles in natural dyes. In India, the use of herbal dyes has been around for a long time and it even can have medicinal effect – in what is known as ayurvastra (the term “ayurveda” refers to the practice of Hindu medicine based on the system of bodily balance). Ayurvastra uses only natural fabrics such as handloomed organic cotton, silk and hemp, where no chemicals and machinery are used. Herbs are concocted to heal ailments such as sleeplessness, high blood pressure etc and the fabrics are dyed in the herbal dyes. It has been a revival in India to promote ayurvastra as textiles that heal, but the actual healing effectiveness of ayurvastra remains to be clinically proven.
2.2. Colour Fastness & Mordants
Besides using concoction of medicinal herbs, textiles can also be dyed using plant-derived dyes. The use of such natural dyes on fabrics appealed to me, and I bought quite a few pieces of tops for myself. My own experience has been that even though the garments sold to me would have gone through quite a few sessions of washing to rid of its residual dyes, the garments I bought still run in the water when I washed them. While the run in the water did not stain my other clothing, this could be a turnoff for consumers. Also, my vat-dyed garments smelled quite strongly. Regarding colour fastness, later I learnt that certain natural dyes tend to fade in colour faster than the rest. Thus, natural dyes usually would need a mordant to ensure a reasonable fastness of colours to sunlight and washing.
A mordant typically refers to metal ions that attaches to the fabric, usually through the process of boiling fabric, so that dyes can attach. Some mordants can be quite toxic, such as chromium, while the least toxic is said to be alum.
One of the dyers I met mentioned to me that they use “gum” on the dyes. I guess he was referring to the use of plant-sourced tannic acid as the mordant. Tannic acid is metal free molecule. The use of tannic acid is usually accompanied by the use of alum.
So it seems that even in the use of natural dyes, one cannot quite escape the use of metals. Furthermore, the colour fastness issue might result in a shorter retainment period of the garment, unless one is happy with his faded look garment or proceed to dye his own garment once again himself. Of course, I have to mention that both synthetic dyed and naturally dyed fabrics can fade in colour, though one suspects that naturally dyed fabrics might lose colour faster over time.
2.3. Water Consumption & Health Concerns
I do not how much more or less water is used in natural dyeing than synthetic dyeing, so I cannot compare water consumption efficiency. The dyer I mentioned above has vats containing the dyes dug in the ground. According to them, the water has never been thrown away and has been re-used in each dye process. Now this is truly environmentally friendly, though I have to admit I cannot help worrying for the workers whose hands are constantly dipped in the dyeing vat.
2.4. Colour Consistency
The colours that turn out in naturally dyed fabrics might vary according to different manufacturing processes and producers. Even under the same manufacturer, there are likely to be differences in colour among batches. While this can be appreciated in terms of authenticity, it will prove to be problematic for garment retailers like me.
2.5. Which Plant To Plant
Obviously certain plants give better colours in terms of vibrancy and colour fastness, such as indigo and safflower. Just like biofuels resulted in real problems of excessive-planting of a single crop (and not meant for food), we should be concerned about sustainable planting of suitable plants for the purpose of natural dyeing, especially in big-scale commercialisation of natural dyes.
- Authenticity – colours that come directly from plants!
- More variety in colours than organically coloured fibres
- Less toxicity than synthetic dyes
- High cost
- Need greater quantity to dye same amount of fabric than synthetic dyes
- Mordants are needed though non-metal mordant is available
- Variety and vibrancy in colours not as much as synthetic dyes
- Consistency problems
- Water consumption?
- Efficiency in the use of resources?
- Sustainability in the growing of plants?
3. Synthetic Dyes
Synthetic dyes quickly gain popularity after its introduction in the 1800s due to its relative cheap costs, colour fastness and ease of application.
3.1 Dye Toxicity
Unfortunately, there are highly toxic, even carcinogenic chemicals used to produce synthetic dyes. For example, the infamous Azo dyes (of chemical Anililine) are considered deadly poisons and highly flammable. Other harmful chemicals include dioxin (carcinogenic), heavy metals (such as carcinogenic chrome, copper and zinc) and formaldehyde – all carcinogens or suspected carcinogens.
3.2 Dye Effluent & Environmental Problems
Irresponsible dumping of used water in industrial synthetic dye process cause serious water and potential land pollution.
3.3 Adverse Skin Reactions
Consumers with sensitive skin could develop adverse reactions towards chemicals in the synthetic dyes, through prolong exposure of their skin (our largest organ!) to clothing.
- Low cost
- Varied & vibrant colours
- Mordants are mostly not needed
- Good Colour Fastness
- Health concerns
- Environmental concerns
4. Low-Impact Dyes or Fibre Reactive Dyes
Though essentially petroleum is still needed for the production of some chemicals, fibre reactive dyes are considered a more eco friendly alternative to direct synthetic dyes, in that they are not very toxic or carcinogenic and heavy-metal free or in very low amount.
Perhaps the best way to strike a balance between natural dyes and synthetic dyes is through international testing and certification system for textiles, such as the Oeko-Tex Standard 100, which limits the use of certain chemicals.
The Oeko-Tex Label is a recognised safety standard in the textile industry that checks for harmful substances at each stage of production processes. Test samples are tested for pH-value, presence of formaldehyde, pesticides, heavy metals and such.
Having written all these, we should be mindful that dyeing is just one part of the textile story. Garment finishing is also another important segment. Special finishings such as wrinkle-free, moisture management often requires chemical treatment that might cause environmental and health issues. I will blog about garment finishing in another post.