Who grew my jeans?

by SDC’s Education Manager, Cat Blackwell

Yves Saint-Laurent once stated that jeans “are expressive and discreet, they have sex appeal and simplicity, everything I could want for the clothes I design.” But what are jeans made out of and why are they so popular?

In the 1860s blue jeans were first invented by Levi Strauss to be worn as a strong and durable material for the workwear market. Over the years they have remained in fashion and become one of the most popular casual wear items today.

denim-1Levi Strauss immigrated to North America from Bavaria following the gold rush in the 1850s to sell his durable work trousers to miners. He used a hardwearing fabric called ‘Serge de Nimes’ originating from France, and leading to the name ‘denim’. Denim is a twill-woven fabric distinguished by a coloured warp yarn and a raw or uncoloured weft. Cotton is a natural cellulosic fibre able to absorb moisture quickly, dry quickly and have a cooling effect when it is warm. In fact cotton can absorb up to 27 times its own weight in water!

How do we make jeans blue?

denim-3The iconic dark blue colour is produced using indigo dye. Indigo is an insoluble pigment without any affinity for cellulosic materials like cotton. This means it has be reduced into its soluble form before application. In this process, an alkali (caustic soda), a strong reducing agent (sodium hydrosulfite) and various auxiliaries are used. The reduced soluble indigo is applied to the yarn in a dyebath using a series of impregnations to reach medium-high intensity colour. The indigo dye is oxidised in contact with air and converted back to its insoluble form, fixed onto the yarn by lots of weak forces of attraction (Van der Waals forces).

Why does the colour fade?

denim-4You may have noticed the blue colour on your jeans fading over time after washing or the colour may transfer to adjacent fabrics, particularly with high intensity colours. This is due to the low diffusion of indigo dye into the yarn as the dye is deposited on the surface in many layers and does not penetrate through to the centre. This, along with any unfixed dye can give the fabric poor fastness, resulting in the fading of colour. Distressed or worn looking jeans can be created using special dyeing and finishing methods to produce a faded and soft look.

Growing the cotton to make your jeans

denim-5Cotton is a natural fibre grown on a plant related to the hibiscus. The cotton plants grow into bushy shrubs and the pink and cream coloured flowers eventually drop off after pollination and are replaced by cotton balls. These cotton balls are made up of a fluffy white lint and cotton seeds. Once collected, they are sent off to the ‘gin’ for processing where the lint is separated from the seeds and pressed into bales ready to be spun, dyed, knitted and woven into fabrics.

Cotton farming uses huge amounts of water, enormous doses of pesticides, insecticides and agrochemicals leading to a large environmental footprint. It is estimated cotton accounts for around 25% of the world’s agrochemicals. Many brands producing jeans have made clear their commitment to reduce the environmental impact of the entire process from sourcing organic cotton to the chemicals used in the manufacturing process. The consumption of vast amounts of water in the manufacturing process and residues generated in the waste water are a major environmental concern which must be taken into consideration when producing a garment.

There are many examples of cotton being grown conventionally which have a much lower impact on the environment and many organisations are striving to make the cotton production process more sustainable. For example, Cotton Australia uses less water, less chemicals and healthier soils than traditional practices. (More information can be found on the Cotton Australia website). The Better Cotton Initiative (BCI) is an organisation that aims to make global cotton production better for the people who produce it and the environment it grows in with the goal to improve sustainability. (More information can be found on the Better Cotton Initiative website).

Is organic cotton better?

denim-6Organic cotton farmers aim to minimise what they see as negative impacts and promote the use of what they view as being positive ones. For example, they focus on natural ways of building soil fertility rather than using synthetic chemicals.

Products with the GOTS symbol ‘Global organic textile standards’ are made from organic fibres, meet strict environmental and social criteria during processing and have been certified by an independent, third party along the whole supply chain. This means dyes and chemicals have met toxicity rules and waste water has been treated before it is released into the environment.

Studies suggest just one t-shirt uses up to 6.5 kg of CO2 during its lifecycle from production to usage, equivalent to a 20 mile car journey.

More information on sourcing of sustainable materials can be found on a number of websites including the Organic Cotton Initative, Sustainable Brands,  and Wrap’s Sustainable Clothing Action Plan.

The ethical dilemma

216hThe Cotton Campaign raises the issue of ethical trade and human rights in the cotton industry highlighting the danger of not knowing how cotton has been produced when bought in the open market. (More information can be found on the Cotton Campaign website). Similarly, the Ethical Trading Initiative (ETI) is an alliance of organisations promoting workers’ rights and freedom from exploitation and discrimination.

The British designer Katharine Hamnett is well known for her ethical, and sometimes controversial, stance on clothing production, so do take a look at her website which has links to some interesting videos, blogs and articles.

You might also want to take a look at this award-winning film, produced by the Environmental Justice Foundation (EJF) White Gold: the True Cost of Cotton.

The ethical and environmentally sustainable sourcing of materials in the fashion industry plays a hugely important part in selecting which textiles to use within the circular economy. What is the environmental footprint of your raw materials? Are the materials you have chosen from an ethical and environmentally sustainable source? Could the materials you use be easily re-purposed or recycled?

Whether our clothes are made from synthetic materials such as nylon or polyester from the petrochemical industry or with natural fibres such as cotton, wool or silk, we must consider the whole environmental impact of producing a garment. We need to fully investigate both sides of the argument to compare the effects not just on the textile industry but the effects on employment, wealth, living conditions and the future of our planet. The choices we make have far reaching consequences that are not always as clear cut as first appears.

The issues raised in this blog relate directly to the theme of the SDC International Design Competition 2017, which is Design for a Circular Economy. Further details are on the SDC website.


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    Excellent comparative arguments, Catherine. Cotton garments bring wearer comfort and some style, but at great environmental cost, as your article says such as water use and damage from large amounts of agrochemicals. Synthetic fibres such as polyester do not have such environmental impact (maybe) but can be processed more readily. Wearer comfort has improved over the last few years also. Dare I suggest that colouration of cottons and other cellulosics will decline in coming years as we head to a better environment with black & white garments for all at lower cost. Shall we continue in future though to wear polyester (the world’s largest produced fibre) and polyamides in colourful amounts? Perhaps the land, the water and the chemicals should be put to better use in the production of local food with a more sustainable footprint? Is this heresy from a dyer and colourist?


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