Embracing natural dyes

Colours brighten up your life – the garment industry is well aware of this and it must currently face increasing challenges. The textile industry is one of the anthropogenic activities that most consume water and pollute water bodies. The textile dyes significantly compromise the aesthetic quality of water bodies, increase biochemical and chemical oxygen demand (BOD and COD), impair photosynthesis, inhibit plant growth, enter the food chain, provide recalcitrance and bioaccumulation, and may promote toxicity, mutagenicity and carcinogenicity.

The textile industry is spread globally, generating around $1 trillion, contributes with 7 per cent of the total world exports and employs around 35 million workers around the world. Despite its undeniable importance, this industrial sector is one of the biggest global polluters and it consumes high amounts of fuels and chemicals. The textile industry is responsible for an extensive list of environmental impacts. The air pollution produced involves, for example, the release of particulate matter and dust, oxides of nitrogen and sulfur and volatile organic compounds. The scraps of textile fabrics and yarns and discarded packaging constitute the primary solid waste. The textile sludge, on the other hand, reveals problems related to surplus volumes and unwanted composition, often presenting high loads of organic matter, micronutrients, heavy metal cations and pathogenic microorganisms.

According to Michael Braungart and William McDonough, on average, only 5 per cent of the raw materials involved in the production and delivery processes is contained within a garment. It is therefore important that we also pay attention to the 95 per cent of the material process that we do not see; a vast component of which is hidden water.

As much as 200 tonnes of water are used per tonne of fabric in the textile industry. The majority of this water is returned to nature as toxic waste, containing residual dyes and hazardous chemicals. Wastewater disposal is seldom regulated, adhered to or policed, meaning big brands, and the factory owners themselves are left unaccountable. Examples of synthetic dyes are disperse, reactive, acid and azo dyes. Natural dyes, meaning colour obtained from naturally occurring sources – are another source of colour for textiles, but these are rarely employed on industrial scales.

Azo dyes are a commercially popular colourant for textiles. They are popular because they can be used at lower temperatures than Azo-free alternatives, and achieve more vivid depths of colour. But some are listed as carcinogens, and under certain conditions, the particles of these dyes can cleave (producing potentially dangerous substances known as aromatic amines). Upon contact with the skin, these can be harmful to humans and pollute water systems. Legislation exists in certain countries, including EU member states and China, that prohibits the sale of products containing dyes that can degrade under specific test conditions to form carcinogenic amines, but low traces of these amines have still been found in garments.

Natural dyes are a frequently suggested alternative, but like many brands guilty of ‘Greenwashing’ their processes, natural dyes on an industrial level give the impression of good behaviour, whilst introducing pollution problems of their own.

With production levels continuing to rise, and consumer demand for colour failing to diminish, alternatives to the current dyeing methods and regulations for water processing must be imposed.

Natural dyes are derived mostly from plants, seeds, fruits, barks, lichens and in some cases, insects. Though natural dyes have connotations of wholesome, toxin free textiles, this is not necessarily the case. Like synthetic dyes, they require a lot of water during production.

Though the dye materials themselves are not pollutants to water, the chemicals employed to fix the colour to the fibres are. These fixative chemicals are called mordants. Ground water and river pollution would occur if metallic compounds were used as mordants and not disposed of responsibly; the same problem synthetic dyes create.

Some natural dyes, known as substantive Dyes, are high in tannins, which can adhere to fibres without the use of mordants. This is an area where small brands and start ups can utilise natural dyes, toxin free and enrich their designs with the narrative of sustainably produced colour. The history contained within natural dyes is an engaging consumer tool.

Many natural dyes are harvested from fragile environments, whilst agricultural land would also be necessary for production of industrial quantities of dye materials. Natural dye pigments only bond with natural fibres, meaning industries relying on petrochemical or regenerated yarns would not be able to use them. Best colour results are achieved on untreated protein fibres, with softer tones on cellulosic. Silk achieves vivid, sumptuous shades, but the silk industry is a point of animal welfare contention in itself. Therefore natural dyes create higher demands for raw materials, not just for the harvesting of dye sources, but for the processing of natural fibres. Treatments and finishes applied to natural yarns to improves fibre performance and extend garment life would also impact colour uptake.

Traceability in the supply chain of growing; harvesting and processing the raw materials present further issues. Indigo has a 5000 year history, from its beginnings as a dye stuff. Exploitation of the Indigo (blue) and Logwood (purple) trades was endemic in earlier centuries. Should natural dyes be employed again on industrial scales, the welfare of workers throughout the supply chain would have to be regulated in order to avoid the repetition of history. Sourcing from accredited suppliers and implementing strict regulations would be essential. As illustrated however, regulations across the fashion industry are inadequate and insufficient.

Important to consider too is the vast amount of land that would be required to grow enough natural dye stuffs to cater for the entire textile industry.

The dyeing process is one of the key factors in the successful trading of textile products. In addition to the design and beautiful color, the consumer usually looks for some basic product characteristics, such as good fixation with respect to light, perspiration and washing, both initially and after prolonged use. To ensure these properties, the substances that give color to the fiber must show high affinity, uniform color, resistance to fading, and be economically feasible.

Modern dyeing technology consists of several steps selected according to the nature of the fibre and properties of the dyes and pigments for use in fabrics, such as chemical structure, classification, commercial availability, fixing properties compatible with the target material to be dyed, economic considerations and many others.

Dyeing methods have not changed much with time. Basically water is used to clean, dye and apply auxiliary chemicals to the fabrics, and also to rinse the treated fibers or fabrics.

Jogindra Industries is one of the leading dyeing machinery manufacturers. JOGSON developed a unique and innovative concept in its own, Multi Pot Sample Dyeing Machine, which is offered from two to up to eight pots on common table either coupled to dye batches of same colour or can run individually to facilitate dyeing batches of different colours simultaneously. This is very useful for standardising the recipes of dyeing before batches are taken in bulk. This avoids trial and error methods, hence saves time and resources utilised. Each pot can range from 20 gm to 10 kg per batch as per the requirement.

On major markets for tubular dyeing machines, Harmeet Singh, Sales & Marketing Director, Jogindra Industries, says, “Considering Indian markets, our major markets for tubular dyeing machines are of northern and extreme southern region. If it is about out of India, then Europe, Bangladesh, Sri Lanka and Vietnam are the areas where there is a high demand of our tubular dyeing machines.”

He added, “ So, Indian textile industry has got a lot of potential and manufacturers including us are strongly working on technology to introduce machines/products equipped with latest technologies by which we can make the end user happy.”

BEZATHREN is the vast range of dyes with unique fastnesses to light, wetness and chlorine on all cellulosic fibres. In recent years the demands made on vat dyeing have thus strongly increased. The CHT Group therefore offers a vast range of efficient vat dyes for cellulose dyeings with a maximum general fastness level.

BEZATHREN dyes comprise an efficient range for vat dyeings on cotton and polyester blends in exhaust and continuous processes as e.g. for sports and outdoor articles, workwear, surgical and hospital laundry, hospital clothes, military articles, and furnishing articles and home textiles.

Natural dyes are therefore not a simple solution to the water pollution crisis but they do represent an important step. Different but equally important and challenging problems arise from their use.