Saturday, December 20, 2014

Natural versus Synthetic Fibers and Dyes
Opinion Piece
Marie-Therese Wisniowski

Season's Greeting
This will be the last post for 2014. The next post will be on the 10th of January, 2015. No matter what your religion or what your belief system, I hope you have a very enjoyable festive season.

Marie-Therese


Introduction
What I am about to write will be undoubtedly controversial since it touches on people’s passions. I have never been one to shirk from an issue nor to bury my head in the sand. I always believe that it is better to raise people’s consciousness, since the costs for not doing so is often very high. Hence this post centers on population growth and the land and water impacts that it may have on base-load supply of fibers and dyes. By base-load supply I mean that it is the major source for the fiber and dye industries.



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A natural dye equation.

The issue is whether natural fibers and dyes are more sustainable (in environmental sense) than synthetic fibers and dyes. The environmental impacts of both need to be considered if we desire that one or the other should materialize as the base-load supply for a growing human population.



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Marie-Therese's synthetic dye equation.
The last artwork - in Marie-Therese's equation - is entitled: Jandabup Wetlands.
Framed Size: 45 cm (width) x 55 cm (height).

Now before I deliver my opinion on this, I need to clarify a few points. The first is to define what we mean by natural fibers or dyes, since ipso de facto all things have a “natural base” if they have been created from substances extracted from this Earth. As far as I am aware, no fiber or dye has been created without an Earthly beginning. There are in fact chemical elements that have been created that are not found on Earth. For example, a number of transuranium elements, unseen in the natural world, were first created in the USA using a man-made device.


Americium was the fourth transuranic element to be discovered. It is not found on Earth. It was created by strong neutron bombardment of plutonium. It was named after the Americas, since it was identified by Seaborg, James, Morgan, and Ghiorso late in 1944 at the wartime Metallurgical Laboratory of the University of Chicago as the result of successive neutron capture reactions by plutonium isotopes in a nuclear reactor.

To clarify concepts that I will be assuming, let us go to my favorite natural dyer – Karen Leigh Casselman. In her tome – Craft of the Dyer – she states in the preface that:
“[Natural] Dyers develop an intuitive interest in and concern for the environment. The dyer learns to know the natural world, and so gains insight into the contemporary application of traditional dyeing techniques to modern craft forms”.

Karen Leigh Casselman, Craft of the Natural Dyer.

Perhaps the definition of natural fibers will be easy to define.
Definition of Natural Fibers: These are fibers that come from animals and plants.

Yep, we are in trouble with this definition since there are a number of synthetic fibers that are extracted from wood pulp. For example, rayon is a manufactured regenerated cellulose fiber. It is made from purified cellulose, primarily from wood pulp, which is chemically converted into a soluble compound. It is then dissolved and forced through a spinneret to produce filaments, which are chemically solidified, resulting in synthetic fibers of nearly pure cellulose. Because rayon is manufactured from naturally occurring polymers, it is often considered as semi-synthetic fiber.

Attempt 2:
Definition of a Natural Fiber: A fiber that is extracted from an animal or plant without the need to re-constitute its form into a different physical configuration by chemical means.

Rayon no longer fits this description.

Rayon made from bamboo. Some environmentalists claim that it is environmentally sustainable since Bamboo requires very little effort to grow and is produced without the use of harsh insecticides, serious pollutants or land degradation and manufactured with minimal chemical input. It is claimed that it is the most renewable resource on our planet, and provides an abundance of usable oxygen making it a crucial element in the balance between oxygen and carbon dioxide in the atmosphere. It cleans the air since it consumes carbon dioxide and, because bamboo forests are so dense, returns 30% more oxygen to the atmosphere than trees. Growing bamboo enriches the soil and its roots stabilize erosion-prone soil. However, what they do not take into account is that as the Earth’s human population is spiraling out of control, and if human demand for bamboo products would also follow the same spiral, bamboo products would assist in the deforestation and dehabitation of natural environments, since competition for land and water is the crux of this problem. Commercial interests have always outweighed the interests of animals (see the yearly deforestation of Indonesia which is forcing the orangutans to near extinction).

Adult male Sumatran orangutan.
Photograph courtesy of Sally Kneidel.

Definition of Natural Dyes: Natural dyes are dyes that are not mass produced by chemical means and moreover, come from plant and animal life that is available from the natural environment.

This definition is already unsustainable since chives, blue berries, bananas, cherries etc. that are sources for natural dyes, are often purchased by natural dyers from man-made farms or markets - whether they are organic or otherwise. Therefore what chemicals that are used in their growth cannot be 100% guaranteed since not all countries have a fully legislated and regulated oversight on the labeling of “organic farming” and on the definition of “organic food”. For example, Australia has only in place legislation and regulation of organic farming and organic produce with respect to export produce only. Local produce has no legislated and regulated oversight. Moreover, the extraction of natural dye stuff from plants usually requires toxic chemicals as well as the addition of mordants.

Pine Leaves – a source for natural dyes.

Second Attempt: Natural dyes are substantive dyes (i.e requires no mordants) that are extracted from plants and animals rather than being chemically created from them.

Not perfect, since there are natural dyes that some would argue are chemically created rather than chemically extracted since they require the dye bath to be at a specific pH and at a particular temperature.

The purpose in trying to define natural fibers and dyes is just to demonstrate how difficult it is to get definitions that circumscribe one class of fiber and dye that we feel familiar with, but in practice is so difficult to isolate from the synthetic variants. It is because in both cases, especially for dyes, chemicals are employed or added to extract/create the dye from raw materials.

Let us pretend there exists a “vegan” of all natural dyers who only employs natural fibers. That is, a person who sources their own natural fiber (and in the case - of say wool - does the shearing, sorting, carding, combing, drawing, roving and spinning themselves etc.) The vegan of all dyers also sources local plants for their dyes from the natural environment and extracts the dye in order to color the woven fabric. As this is the “vegan” of all natural dyers, the person would use substantive dyes stuff (i.e. natural dyes that will impart color to a fiber without the use of mordants); for example, boiling most water lichens are in this category.

Turmeric is a substantive dye.

A few natural dyes, such as logwood, which contains hematein and hematoxlyn, are themselves significantly poisonous – they are toxic whether inhaled, absorbed through the skin or ingested. The dye color depends on the mordant used (i.e. a heavy metal such as tin or alum) as well as on the pH (i.e. acidity of the dye bath).

Let us investigate these two extremes: the anything-goes dyer who unashamedly purchases factory made fibers and dyes (e.g. polyesters and disperse dyes) and the not-so-vegan dyer, who wants to use substantive and adjective dyes stuff (i.e. requires a mordant to fix the color and make it fast) and who sources some their natural fibers and some of their dye materials from from craft shops or markets (e.g. chives). I will maintain that once you outsource your purchase, you cannot be sure that an ethical purchase has been made. Only the “vegan” dyer, who has created their own dye, fiber, yarn and fabric can certify the ethics that underly each step of the process.

I will also maintain that if the “vegan” dyer wants to embrace such a lifestyle or just enjoys to work with natural fibers and dyes, all is well both in terms of their personal sustainability and ethical practices. I was a teenager of the 1960s and 70s and so I am quite relaxed with people, who want to choose a lifestyle or who wish to choose the tools they want to work with (i.e. natural fibers and dyes); communes and co-operatives were all the rage in those days. It is okay for the vegan dyer to state that this my lifestyle or my choice of tools and since I am not harming the environment nor anyone else, then let me be!

Modern Utopia: alternative communes of the 60s and 70s.

More importantly, I will argue that with the world population spiraling to 9 billion the base-load supply for fibers and dyes should mostly come from synthetic sources since they are far more sustainable in a base-load supply sense than natural fibers and dyes - if you take into account the excessive land and water footprint that natural fibers and dyes would require if they were the base-load supply of our fiber and dyeing industries.

To make my argument, I will separated it into three basic components:
(a) The ethical dimension (which is often incorrectly conflated with the comparison between natural and synthetic fibers and dyes).
(b) A close inspection of fibers - as to which can realistically be the base-load supply.
(c) A close inspection of dyes – as to which can realistically be the base-load supply.


Ethical Dimension
It is often been argued that natural dyers sit on the moral high ground, since there are lots of examples that synthetic dyes pollute our water systems, soils and atmosphere. Here lies the confusion between ethical buying/consumerism versus a sustainable base-load supply to the fiber and dye industries at large.

Poor environmental practices should always be routed - root and stem - once they have been exposed. Countries that have no environmental legislative and regulatory oversight of the environmental impacts of their fiber and dye industries should not be allow to export their products to the countries that do. Claiming that synthetic fiber and dye industries are polluting waterways, soils and atmosphere is not due to their inherent properties of manufacture, but I will maintain is due to lack of legislative and regulatory oversight.

Let us take two examples to illustrate how different production processes - that yields the same fiber in different legislative and regulatory jurisdictions - can result in significantly different environmental impacts.

Lenzing is an Austrian company. It produces viscose in Asia - that operation will be labeled as Lenzing Viscose Asia. In Asia it makes the fiber using imported pulp based on eucalyptus wood, which is produced from man-managed forest in the southern hemisphere. The fiber plant is representative for the state-of-the-art separate viscose fiber plant based on wood pulp in the world. On the other hand, Lenzing also make viscose in Austria - that operation will be labeled as Lenzing Viscose Austria. The most important difference between Lenzing Viscose Asia and Lenzing Viscose Austria is the integration of pulp and fiber plants. The Austrian viscose fiber plant is integrated with a pulp mill, while pulp and fiber production are separate in the case of Viscose Asia; in this sense, Lenzing Viscose Austria represents the best available technology (BAT) of the current global viscose fiber production.


Viscose Jersey fabric.

An in-depth study by Shen and Patel[1] has concluded that:

“…an integrated fiber-pulp production (i.e. as used in the production of Lenzing Viscose Austria) leads to much lower environmental impacts than the separate production of pulp and fibers (i.e. Lenzing Viscose Asia).

The environmental benefits of Lenzing Viscose Austria are largely attributed to low fossil energy requirements in the pulp and fiber production. This is a result of both process integration and the use of renewable energy. Furthermore, Lenzing Viscose Austria has much lower process emissions (e.g. SO2 and NOx) than Lenzing Viscose Asia, leading to lower impacts on human toxicity, photochemical oxidant formation, acidification and eutrophication” - end of quote.

The same end product – Viscose - produced by two different pathways in two different and distinctive legislative and regulatory settings by the same company produces two different environmental impact results. In other words, the European Union legislative and regulatory restrictions are far tougher than in Asia requiring the company Lenzing to adopt more eco friendly processes in Austria compared to the legislative and regulatory system in Asia.

Cradle-to-the gate energy use for man-made fibers. Cumulative energy demand (CED) is the sum of non-renewable energy use (NREU) and renewable energy use (REU). The CED of man-made cellulose fibers is 65-106 Gigajoule per ton (GJ/t). Note: Lenzing Viscose Asia uses 61GJ/t of non-renewable energy in their production, whereas Lenzing Austria due to different legislative and regulatory requirements (e.g. emission trading scheme introduced by the European Union) uses only 19GJ/t of non-renewable energy.

Over the past decade we are becoming more aware that as consumers we should be asking more questions about labor laws (or the lack thereof), about pay-rates, working conditions and occupational, health and safety (O, H & S) issues in the workplace of countries where our fibers and dyes are made. For example, headlines like these below were commonplace just a few years ago:

”Forced to stand for 24 hours, suicide nets, toxin exposure and explosions”: Inside the Chinese factories making iPads for Apple."

”Nike has been accused of using child labor in the production of its soccer balls in Pakistan”.

Ethical consumerism is starting to take hold. The consumers have forced both companies to investigate their supplier’s workplace practices in third world countries. CEO of Apple Tim Cook responded:
”Every year we inspect more factories, raising the bar for our partners and going deeper into the supply chain," Cook said. "We've made a great deal of progress and improved conditions for hundreds of thousands of workers.”

The more you outsource, the less control you have of the ethics of those who supply you. Hence, natural and synthetic dyers using cotton (a natural fiber) that they did not pick or make into a fiber may be underwriting operations that would appall them. For example, recently it was reported that:

“Whilst students in the UK are in school, going from lesson to lesson, finishing school and going home to their families, every September and for up to three months, hundred of thousands of children in Uzbekistan, some as young as nine, are being forced out of school to pick cotton by hand”.

Similarly, buyers of colored silk from India may not be pleased to know that the occupational, health and safety laws in India are so poor and moreover, so poorly oversighted in both a legislatively and regulatory sense, that it is commonplace for dyers to end-up with arms like these.

An indigo dyer - using a natural dye - in India. Poor legislative and regulatory oversight creates dyed skin for the untouchable caste dyers in India. Even natural dyes are harmful without the necessary legislative and regulative oversight.

The not-so-vegan and anything-goes dyer has all of these ethical problems to contend with. Once you out source - you loose control of the ethics of those who supply you.

None of us, whether we use synthetic fibers and dyes or natural fibers and dyes, want in-humane working conditions that put people’s lives at risk or causes permanent damage. Hence, the not-so-vegan and the anything-goes dyers need to ask questions in order to ensure that ethical consumerism will eradicate the exploitation of the vulnerable. But the question of whether products are ethically made is an independent question to the question of whether natural or synthetic fibers and dyes should be the base-load supply for the world’s growing population.


Current and Predicted Production of Natural and Synthetic Fibers
Most of this information given below has been extracted from a power point presentation given by James Mills, Business Manager of Polyester and Intermediates, Tecnon OrbiChem at the AFCOT conference at Deauville (France) on the 6th October 2011. All comments not given in a slide in this section belong to the author – Marie-Therese Wisniowski – and not to James Mills nor to Tecnon OrbiChem.

Disclaimer: Marie-Therese Wisniowski, Art Quill Studio and parent company Art Quill & Co Pty Ltd have no shares or financial dealings with Tecnon OrbiChem or James Mills.

We must agree that the world’s human population is on the increase and I would maintain is spiralling out of control. The United Nations have predicted that by 2050 the human population on this planet will exceed 9 billion people.

United Nation’s predicted growth of the human population on Earth.

Clearly the need to house, clothe, shelter and produce manufactured goods will place a greater demand for fiber. The world demand for fiber between 1960 and 2009 is fairly linear with respect to Gross Domestic Product (GDP). The two lines shown have similar gradients and have similar R2. Note: the closer R2 is to the numeral value of one, the more confidence there is that a linear relationship exists between the two. The richer we are, the more fiber we use and have - with respect to apparel and manufactured goods.

Linearity between demand for fiber and GDP (1960 – 2009).

Between 1900 – 2010, as the population has increased, the demand for natural fibers and synthetic fibers has also increased, with the demand for synthetic fibers in 2010 being approximately twice that of natural fibers. Cellulosic fibers have stabilize in demand in the latter years of the graph.

World fiber demand 1900 – 2010.

What is interesting is to get a feel for amount of fiber per person (or per head) that is being consumed. Whilst natural fibers are below ca. 5kg per head over that period graphed, synthetic fibers have grown to over 7kg per head in the same period.

World per capita fiber consumption.

The world fiber production between 1980 – 2025 yields an interesting plot. Of the natural fibers, it is clear that demand for wool is much smaller than the demand for cotton or cellulosic fiber, whereas of the man-made fibers only polyester demand is larger than cotton, with this trend accelerating 2011 – 2015 (i.e. by 2020 demand for polyester fibers will be ca. 2.5 times larger than cotton). It should be noted the wool is a very expensive fiber as is silk, which may explain their relatively small production scale, when compared to cotton.

World fiber production from 1980 – 2025. Note: 2012 – 2025 are predicted, following 1980 – 2011 trend lines.

James Mills’ summary of the above slides and a summary of the information they contain.

By 2020 the manufacture of polyester will be dominated by China, South and South-East Asia. This has ramifications in terms of ethical consumerism (see above); that is, legislative and regulatory oversight of working conditions (O, H & S, conditions of employment etc.) and environmental impacts have been generally poor in these countries.

World polyester staple production.

James Mills’ predictions. Note: he states that the re-cycling of polyester fibers is of the order of 50% in some regions. This feature significantly reduces the environmental impacts using this synthetic fiber. For example, regeneration vastly reduces energy usage, atmospheric, aquatic and soil pollution as well as waterwaste disposal etc.

A similar world outlook of polyester filaments.

World polyester filament production.

James Mills’ summary of polyester filament outlook.

World cellulosic fiber production.

James Mills’ synthetic fiber summary. Note: the last point is of particular importance from an environmental impact point of view – see my above comments.

Demand for cotton varies according to price. If the price of cotton falls significantly below the price of polyester then cotton production will increase. As polyester is made from petroleum, its price is linked to this raw material.

World cotton production 2000 – 2025.

James Mills’ comments about the competition between cotton and polyester.


Base-Load Supply: Natural or Synthetic Fiber – Which is More Sustainable?
It is clear that the land footprint of polyester is negligible since it is derived from petroleum, whereas there are sizeable land impacts with respect to growing cotton. For example, polyactide (PLA) is an aliphatic polyester. Shen and Patel[1] have researched the environmental impacts of PLA and cotton. Their graph below compares land impacts of various fibers. However, for the purpose of this section only PLA and cotton are of concern to us. They have compared the land use of one ton of staple fiber. Hence the vertical axis has units of hectare (ha) per ton of fiber produced – the larger that figure the more impact the fiber will have on deforestation and dehabitation. Forest land used and agricultural land use are indicated by vertical and crossed hatch respectively.

Land use for one ton of staple fiber.

Their study shows that on an average, cotton would consume 300% more land than PLA. If cotton replaced polyesters then the land impacts would be devastating for animals that exist in the wild, especially in 2050 where the world’s population will exceed 9 billion people. Hence no one decries the use of natural fibers, but they are more useful in blends than they are as the base-load supply for the fiber industry.

Furthermore, in the same study[1] these authors published water usage.

Water use for one ton of staple fiber based on natural water origin (m3 per ton fiber).

It is clear that petroleum fibers such as polyesters consume far less water (process + cooling) than the irrigation water that cotton consumes.

In conclusion these authors state that[1]:
“Based on the normalized results, we conclude that the fresh water aquatic ecotoxicity and terrestrial ecotoxicity of cotton is very high; all man-made cellulose fibers studied cause comparatively insignificant impacts to human toxicity, fresh water aquatic ecotoxicity and eutrophication; and all man-made cellulose fibers, PET, PP and cotton have minor contribution to ozone layer depletion and photochemical oxidant formation.”

In summary, polyester is an environmentally friendly fiber since:
• The raw materials are relatively easily accessible.
• The chemical process of polyester synthesis is simple and very well understood.
• All raw materials and side products have low toxicity levels.
• It can be produced within a closed loop at low emissions to the environment.
• It has outstanding mechanical and chemical properties enhancing it as a textile.
• A wide variety of intermediate and final products can be made from it.
• It is recyclable.

It is for all the above reasons that all of my environmental ArtCloth imagery is based on polyester (delustered satin). My reason is simple - I never want cotton to replace polyester and become the based-load supply for the fiber industry at large. Anthropogenic climate change is real. With a population spiraling out of control we need to find sustainable fiber sources in order to reduced our land and water footprint so that animals can exist in the wild. Deforestation and dehabitation needs to be arrested!


Environmental Risks Associated with the Use and Disposal of Synthetic Dyestuffs
Dyes may be classified according to chemical structure (e.g. azo dyes, anthraquinone dyes) and/or by their usage or application method; very often, both terminologies are used. Classification by usage or application is the principal system adopted by the Colour Index International. In some cases, the same colorant is present in more than one application category; for example, typically, a disperse dye can often be applied as a solvent dye.


Dispersed dyes.

The disperse dye class refers to substantially water-insoluble, non-ionic dyes used for application to hydrophobic fibers from aqueous dispersion. Disperse dyes are primarily used for the dyeing of polyester, polyester blends, nylon (polyamide), cellulose fibers (acetate and triacetate) and acrylics. The solvent dye class refers to dyes that are water insoluble but soluble in solvents that do not contain polar solubilizing groups such as sulfonic acid, carboxylic acid or quaternary ammonium. Solvent dyes are used for coloring plastics, gasoline, oils and waxes.

Jacquard Dye for naturals & polyesters - Jacquard iDye Poly for polyesters/nylons (disperse dye).

Azo disperse dyes refer to dyes that contain one or more azo bonds (i.e. two nitrogen atoms joined by a double bond) that are used as disperse dyes and represent the largest group of disperse dyes, accounting for more than 50% of the total commercialized disperse dyes in the world[2]. Polyester fibers are almost exclusively colored with disperse dyes. Historically, disperse dyes were first used to dye cellulose acetate. Since 1950, the production of disperse dyes has increased sharply, closely following the worldwide production of synthetic fibers, especially polyester, which has grown steadily. Disperse dyes have been and are still being used for a significant segment of the nylon textile business[2]. Cellulose and polyester fibers account for 78% of world textile consumption, which is steadily increasing worldwide. Disperse dyes have the largest market share of all textile dyes and accounted for 28% of the world textile dye market in 1998.

Disperse dye orange 1 is an azo dispersed dye.

Azo disperse dyes generally have good light fastness (i.e. the ability of a color to resist fading when exposed to light), while fastness to washing (resistance of color to fading when the textile is washed) depends mostly on the fiber used. In particular, for polyamide and acrylic fibers, azo disperse dyes are mainly used for pastel shades. Azo disperse dyes are available in powder or liquid form. Powder forms contain 40–60% dispersing agents and liquid forms contain 10–30% dispersing agents.

The global consumption of textiles is estimated ca. 30 million tons, which is expected to grow at the rate of 3% per annum[3]. The coloration of this huge quantity of textiles requires ca. 700,000 tons of dyes, which may cause release of a vast amount of unused and unfixed synthetic colorants into the environment[3]. Synthetic dyes will remain the cornerstone of the industry (see below) since consumers will always demand a full palate of colored textiles for eye-appeal, decoration and even for aesthetic purposes that are light fast, color fast and wash fast. Moreover, such a huge amount of textiles materials cannot be dyed with natural dyes alone (see below). Hence, the use of eco-safe synthetic dyes is also essential. However, a certain portion of colored textiles cannot always be supplemented and managed by eco-safe natural dyes. Moreover, it should be noted that not all natural dyes are ecofriendly. For example, there may be presence of heavy metals (e.g. mordants) or some other forms of toxicity in natural dye. So, natural dyes should also be tested for toxicity before their use as a base-load supply for the industry.

Madder root dye wool using an alum mordant and dye bath at 50oC at pH 4.

During the last decade, the worldwide dyestuff industry has been characterized by significant oversupply, resulting in severe pressure on prices. As a result, most dyestuffs producers have suffered significant financial losses and major restructuring has taken place, especially in the United States, Western Europe and East Asia, including Japan, the Republic of Korea, and Taiwan.

Currently, the major dye sourcing country is China, followed by India, Western Europe (mainly Germany and Switzerland) and Taiwan. Major export markets include Turkey, Brazil, Japan, Indonesia, the United States, the Republic of Korea, Mexico, and Thailand[4]. China has the largest trade surplus, followed distantly by India and Western Europe[4]. Since 2002/2003, both Turkey and Brazil have gradually increased their dependency on imported dyes, as the dye consuming industries have expanded in these countries.

Pie chart shows world consumption of synthetic dyes.
Courtesy reference[4].

During 2006–2010, consumption of dyes decreased in North and Central America, Western Europe, and Japan, while it increased in South America, Central and Eastern Europe, the Middle East, Africa, and Asia (with the exception of Japan)[4]. Japan was hit hard during the 2008/2009 economic recession. Other Asian countries were not hit as hard[4].

Consumption of dyestuffs is governed predominantly by several factors[4]. The primary long-term factor is demand for textiles, leather and colored paper. Consumption of textiles, the largest end-use market for dyestuffs, in turn depends directly on population growth and private (consumer) spending levels[4]. The most important short-term factor is fashion, which dictates the types of colors used. The quantity of dyestuffs consumed per textile volume is considerably higher when bright or dark colors are desired than when only light colors are in demand[4]. Hence, the colors used for textiles have an impact on the total consumption of dyestuffs. A lesser but still potentially important factor is the substitutability of organic pigments for dyes, particularly in the textile printing segment but also in other segments such as plastics and inks. On the other hand, specialty dyestuffs may also substitute for pigments in selected markets; an example is the dyeing of modified polypropylene fibers, which are normally pigmented.

Asia will continue to be the largest and fastest growing market for textile dyes, as textiles remain a high-volume traded commodity produced in this region[4].

There are concerns about synthetic dyes and the impact they have on the environment, especially in developing countries where synthetic dyes are often sourced[4]. For example, synthetic dyes find use in a wide range of industries that are of primarily of importance to textile manufacturing. Wastewater from the textile industry can contain a variety of polluting substances including dyes[4]. The environmental and subsequent health effects of dyes released in textile industry wastewater are becoming subject of further scientific scrutiny.

In recent years, new legislation has affected dyestuff product portfolios. For instance, the European Commission banned many azo dyes in 2002 and navy blue (a chromate-based azo dye, one of the most widely used dyes in the leather industry) in 2004[4]. Restrictions on azo dyes have impacted major dye and textile exporting countries such as India. China and India, which together account for some 66% of global dye production, are sensitive to such regulations[4]. The ban on vat and azo dyes in some countries has paved the way for reactive and disperse dyes in India. REACH (the European Union regulatory arm for chemicals), which was enacted in 2007, also affects consumption of synthetic dyes[4]. In China, several dye and textile factories have been closed by the government for being either too polluting or too energy intensive. Both Chinese and Indian textile dyes and chemicals suppliers are faced with the challenge of reducing pollution and optimizing the use of resources[4].

REACH is the Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals. It entered into force on 1st June 2007. It streamlines and improves the former legislative framework on chemicals of the European Union (EU).

Although there are no current expected human health exposures in developed countries such as Canada, six azo disperse dyes (CAS RN 93805-00-6 and CAS RN 65122-05-6 Disperse Yellow 23, Disperse Yellow 7, CAS RN 58104-55-5, and Disperse Red 151) could produce metabolites that are recognized for their high human-health hazard. There may be concerns if uses resulting in exposure were to increase in any country. Options on how best to monitor changes in the use profile of these substances, such as monitoring of international activities or surveillance of the marketplace, have been investigated in developed countries such as by Canada[5] as the assessments for all of the aromatic azo and benzidine-based substance grouping are completed, to ensure consistency across this grouping.

Chemical formula of Disperse Dye Red 151. The two N=N bonds (nitrogen nitrogen double bonds) is why it is classified as an azo compound.

In summary: Despite the better performance of synthetic dyes and stringent legislative and regulatory oversight in developed countries, recently the use of natural dyes on textile materials has been attracting more and more scientific research for the following reasons:
(i) Natural dyes have a wide-range of sources.
(ii) Experimental evidence for allergic and toxic effects of some synthetic dyes, may lead to being replaced by non-toxic and non-allergic natural dyes.
(iii) To protect the ancient and traditional dyeing technology, generating livelihoods with respect to poor artisan/dyers of developing countries.
(iv) To generate sustainable employment and income for rural and sub-urban areas both for dyeing as well as for non-food crop farming in order to produce raw materials for natural dyes.
(v) To gather scientific information on chemical characterizations of different natural colorants, including their purification and extraction.
(vi) To obtain a knowledge base and database on application of natural dyes on different textiles.

Dyers in Kalasin Province, Northeast Thailand, 1986.
Photograph courtesy of by H.L. Lefforts.

In a major review article on the application of natural dyes on textiles, Samanta and Agarwal[4] have concluded that:
(i) The required scientific studies and systematic reports on dyeing of textiles with natural dyes is still insufficient and inadequate.
(ii) The natural dye knowledge base and database with production of appropriate shade cards for different textiles is still inadequate.
(iii) Reproducibility and color fastness for natural dyes is still problematical.
(iv) Improved computerized color matching for use of synthetic dyes has now become a regular practice in most of the textile industry (except jute industry). It has still not possible for natural dyes mainly due two dependent factors (dye and mordant) and color development mechanism of natural colors when applied to textiles. Prediction of a color match by controlling these two variables (dye and mordant) simultaneously is not possible by the latest technology known so far.

In developed countries, both legislative and regulatory oversight is being imposed to control the release of synthetic dyes, in particular azo-based compounds, into the environment. For example, in Lake Macquarie (Australia) where I live, dyes that are washed out even from silk screen in commercial operations are not allowed to enter the sewage or wastewater systems without prior treatment. They must enter separation tanks where the settled dye stuffs are pumped out by licensed operators and then legally disposed of in effective sludge treatment plants.

In commercial operations wastewater from the textile industry is a complex mixture of many polluting substances ranging from organochlorine-based pesticides to heavy metals associated with dyes and the dyeing process. During textile processing, inefficiencies in dyeing result in large amounts of the dyestuff being directly lost to the wastewater, which if unlegislated and unregulated, will ultimately find its way into the environment.

Colorants that enter the wastewater streams normally pass through a wastewater treatment plant where they are eliminated to a large degree by adsorption in sludge. The extent to which residual amounts reach the surface waters depends on the efficiency of treatment processes. Low concentrations of dyes in wastewater do not normally pose any significant environmental hazard. Environmental problems arise mainly from inefficient removal of dyes or disposing the untreated dye effluent to water receiving bodies. The latter is normally the case in most developing countries where legislative and regulatory oversight is absent or negligible.

Dye pollution from textile plants is a source of environmental concern in China.

Nevertheless, as developed countries have banned the use of dyes, especially azo dyes, this has forced developing countries to alter their product portfolio and so has indirectly assisted lowering environmental risks associated with dye manufacture and use in these countries.

There are also scientific studies underway to make synthetic dyes even more eco friendly. For example, Kant[6] has reported that a solution appears to be in sight with the coming of “Air Dyeing Technology” for synthetic dyes. Air dyeing technology is a dyeing process that uses air instead of water to dye synthetic garments, allowing companies to create garments with vivid designs and colors, without polluting the water and the environment. Its advantages are that it:
(i) uses 95% less water.
(ii) emits 84% less Green House Gases (GHG).
(iii) requires 87% less energy.
(iv) reduces damage to goods (i.e. up to 1% of goods 
are damaged using Air Dyeing procedure as compared 
to 10% of traditionally dyed garments).
(v) has no rules to washing. Air dyed fabrics can be washed at any temperature, with whites or colors, with or 
without bleach.
(vi) allows for new designs. Different sides of a single 
piece of fabric can be dyed in different colors or e-signs.


This unique dyeing process is already in use to create 
vibrant, double-sided swimsuits, 100% recycled PET eco-chic t-shirts, window coverings, designer handbags and runway fashions of New York design house.

Dry dyeing apparatus. This new process utilizes supercritical fluid carbon dioxide (CO2) for dyeing textile materials. It is a completely waterless dyeing process using only nominal amounts of recycled CO2. Dry-Dye fabrics dyed with this unique waterless process will have the same quality of dyeing as current, conventionally-dyed fabrics.

Comparison of Air Dyeing (yellow) and Traditional Wet Dyeing (purple) process for 25,000 medium men’s t-shirts: (a) Water (gallons); (b) Energy (Mega joules); (c) Greenhouse Gas (kg CO2 equivalent emissions).

In summary, natural dyes cannot at this juncture replace synthetic dyes in terms of the ease of use, having an extensive color palette, effective dyeing of synthetic fibers (such as polyester), and fastness (wash, light, color, abrasion etc.) Furthermore, not all natural dyes are eco friendly.

There are eco friendly problems with synthetic dyes especially in terms of their production and use in developing countries where legislative and regulatory oversight is poor. In developed countries, they pose less environmental hazards, since such oversight is on-going in monitoring the environmental impact of synthetic dyes (e.g. see creation of REAL in the European Union).

However, if more data on natural dyes was produced could they eventual replace synthetic dyes as a stable base-load supply for dye industries without impacting on deforestation and dehabitation?


Base-Load Supply: Natural or Synthetic Dyes – Which is More Sustainable?
Now that we have rightly quarantined the arguments about ethical buying/consumerism from the base-load supply argument, let us investigate the land and water impacts of natural dyes as a based-load supply more forensically. However, before we do let me make this statement at the outset. I will maintain that if you are a natural dyer and use natural fibers, land and water impact is not a problem for you. Chances are you live in a well-to-do country (not third world), have some time on your hands, and enjoy your hobby/craft/art. If we could summed up all the natural dyers and fabric hobbyists/crafters/artists - which is an impossible sum to do since there are no official “natural” registers that track them and their outputs - my educated guess would be that the total land and water footprint that they would use would be absolutely miniscule. Hence I have no issue at all with natural dyers as a lifestyle choice or as a choice about which tools to use (fabrics and dyes). Note: in the exhibition I curated - ArtCloth: Engaging New Visions - natural dyers who used natural fibers produced excellent artwork and were one of the highlights of the exhibition.

Jurate Urbiene, Quite Alone Oasis (full view).
Natural dyes and fibers were used to create this artwork for the - ArtCloth: Engaging New Visions exhibition.

However, I would have issue if synthetic dyes were banned and only natural dyes were instituted as the sole based-load supply for the fiber and dye industries.

I will cite some data given in an O ECOTEXTILES article[7] which looks at natural versus synthetic dyes and happily re-state their case here in order to make it clear why synthetic dyes are sustainable and natural dyes are not - in terms of the land and water footprint. Note: not all points made below came from the article[7]. In fact, I have paraphrased and re-cast the argument[7] in order to put a greater emphasis on the impact of deforestation and dehabitation. To read the original argument, please go to the web site[8]. Nevertheless, the conclusion O ECOTEXTILE reached - that natural dyes cannot replace synthetic dyes in a sustainable manner - is identical to my own position.

Just because dyes are natural does not mean that they are sustainable, especially if they are organically raised or harvested, since in case of organic farming far more land would have to be consumed because of crop losses. For non-organically grown crops, pesticides, herbicides, defoliants and other chemicals are usually involved in order to minimize crop losses and/or to enhance uniformity or growth etc. Also the crop itself may have been genetically modified or irrigated unsustainably, depending on where and when the crop was grown (e.g. under drought/flood conditions, planted in regions where climate and soil conditions were unfavorable for crop growth etc.)

If natural dyes were used as the base-load supply the extraction of the dye from the plant or insect may have involved harmful chemicals that may appear in the wastewater, and so creating a problem of wastewater disposal. For example, the extraction of madder is often done by dissolving the roots in sulfuric acid and using mordants (e.g. tin, lead or alum etc. to fix a color); sodium hydroxide is needed to produce natural indigo dye. Where do these wastewaters go after they have been used to extract copious amounts of dyes needed to generate a base-load supply for the fiber and dye industries?

The physical amount of natural dyestuff needed to color fabric is much greater than that required by synthetic dyestuffs (and this is a critical point). The amounts needed vary by dyestuff used and fiber type, but as an example, O ECOTEXTILES have summarized the usage from an article in the Clothing and Textiles Research Journal[8]:
(a) To dye two yards of upholstery weight fabric, 0.7 ounce of a synthetic dye was required, whereas 160 to 320 freshly picked leaves were needed.
(b) To dye 5,000 yards of cotton, 109 pounds of synthetic dye was needed, whereas 938-2500 pounds of madder was required or 25,000-50,000 freshly picked leaves were required.

Madder root.

There are two worrisome aspects to these figures. The first is the variability of the natural dyes compared to the exactitude of synthetic dyes. Imagine if you are running a commercial enterprise and you are trying to quantify the amount of dye you need. In the case of natural dyes the quantity would vary with each batch of raw materials making such a process impossible to predict costs and to predict the effectiveness of the dye in coloring the textile. For each batch of natural dye raw materials, testers would be required to be performed in order to assess, for example, how many leaves would be needed in this batch to effect an adequate coloring etc., thereby increasing the time for the dyeing process and the cost of dyed fabrics.

The second and more important worrisome point is that the quantity of dyestuff required is not a trivial consideration as the quantity of natural dyes that would be required to fulfill commercial dye demand would overwhelm land and water resources. Some dyestuffs come from forest products, depleting valuable natural resources. Some, can be harvested in the wild, but the population of creatures or plants required to fill human dye demand could not be supplied from current stocks of plants or animals. The third class of natural dyes – minerals - is less objectionable in this regard. According to Ecotextile News (April 2009), it has been calculated that even if 2/3 of the world’s agricultural land was used to exclusively grow only natural dyes, there would be scarcely enough produced to dye the current volume of textiles. With over 9 billion people predicted to be on the Earth by 2050 this equation would become even more problematical.

Indigo Farms just on the border of North and South Carolina.

Natural dyes normally require much greater energy in the dyeing process as they usually require high temperature baths for longer periods of time than the optimized synthetic dyes; they also require a copious amount of the dyestuff itself (as mentioned above) and water. This would impact on energy and water consumption significantly.

The use of natural dyes will almost certainly make colored fabrics more expensive, firstly, because large quantities of land and raw materials are required in order to obtain the same depth of color that could be obtained from a synthetic dye. Also, both growing and applying the dyes is a time-consuming business - natural dyes take typically at least twice as long as synthetic dyes to get a result, and using natural dyes on vegetable fabric would be more costly still, as vegetable fibers are more resistant to taking up good strong colors than animal fibers are, and slower, longer treatments using natural dyes often yield better results. So the question becomes one of social responsibility – is it responsible to use land to produce ultra low yield dye crops for the benefit of those wealthy enough to afford them?

And then there’s the problem of availability: with perhaps the exception of indigo, the most common dyeing crop, crops grown for dyes are almost non-existent. A manufacturer would have extreme difficulty in making vast farm investments (or encouraging others to do so), since the supply and the infrastructure does not at present exist on an industrial scale.

As Ecotextile News reported: “Nature alone can’t meet the technical or volume demands of the modern consumer, and petroleum technology isn’t sustainable.”

However, petroleum products do give us a sizeable time-base in order to discover new sources for synthetic fibers (e.g. fossil coal which is now mainly used for energy consumption), without resorting to the wholesale destruction of the natural flora and fauna, which would occur if natural dyes became the base-load supplier of dyes to the fiber and dye industries.


Conclusion
As the human population spirals out of control, humanity needed to concentrate infrastructure and services and so has moved from hunters and gathers to subsidence agriculture to city-states to establishment of countries to mega trade blocks (e.g. European Union). At each step more and more people have been concentrated in fewer areas and so more and more mega cities have been developed in order to “free up” land in order to ensure greater and more efficient food, clothing, shelter, material and energy production.

However, as the human population keeps spiralling out control, more and more land will be used to service human needs. Even now large swaths of land are reclaimed in order to meet those needs. For example, land has been captured from the sea (e.g. Netherlands), swamps have been drained (USA), and forests have disappeared. In Australia, large areas of land have been garnered for wood pulp in order to create paper products such as for packing or for words. These forests are pine forests, which are foreign to this continent and so no native animal knows how to exist within these plantation in terms of garning food or shelter. These pine plantations are devoid of animal sounds and so are silent deserts of sorts.

Whilst any products made from petroleum are not sustainable in the medium term, they do give us time to find new feed stocks (other than flora) that will produce synthetic fibers and dyes and in that process become more sustainable and more ecofriendly. In the long term, nothing is sustainable since the Sun has a finite lifetime!

My environment ArtCloth is directed at preventing the deforestation and dehabitation of the Earth - in my lifetime at least. It is similar to the posters of yesteryear protesting against the inevitable, but instead of hurling slogans (e.g. Make Love not War!) it is aimed to arouse your innermost passion to try and save the hidden and the vulnerable from becoming extinct in the wild.

I often get asked – why is your environmental ArtCloth not using natural fibers and dyes? Very few understand my answer when I state that to do so would be sending a wrong message. I hope if you have read this post you know where I am coming from.

Marie-Therese Wisniowski, Global Warming - Surviving Remnants.
Technique: MultiSperse Dye Sublimation technique on satin.
Size: 20 (width) x 20 (length) cm.
Collected By: The Americas Biennial Exhibition & Archive Collection, University of Iowa, Iowa, USA.


References:
[1] L. Shen and M. K. Patel, Lenzinger Berichte, 88 (2010) 1-59.

[2] Industrial Dyes: Chemistry, Properties, Applications. Edited by Klaus Hunger. Wiley-VCH, 2003.

[3] A. K. Samanta and P. Agarwal, Indian Journal of Fibre and Textile Research, 34 (2009) 384.

[4] HIS - http://www.ihs.com/products/chemical/planning/ceh/dyes.aspx.

[5] http://www.ec.gc.ca/ese-ees/default.asp?lang=En&n=0F6111A3-1.

[6] R. Kant, Natural Science, 4 (2012) 22.

[7] OEXCOTEXTILE - https://oecotextiles.wordpress.com/tag/natural-dyes.

[8] Chen and Burns, “Environmental Analysis of Textile Products”, Clothing and Textiles Research Journal, 24 (2006) 248.