[Sustainable Tuesdays] Back to the mill – The how of textile recycling

Sustainable Tuesday - Clothes recycling

It’s a Sustainable Tuesday again, y’all, I bet the knowledge geek inside is looking forward to another foray into the world of all things sustainable… So I oblige!

As I was writing last time about how great it is that wool can be recycled, I came up with today’s subject: how are textiles actually recycled and what challenges are we still facing until it will be possible to turn old into new at the end of the garment’s useful life?

For either environmental (resource scarcity, environmental effects of textile agriculture or animal farming for fibres, landfills filling up, results of dying and garment manufacturing) or economic (increase raw material prices, cost of raw material processing) reasons, textile recycling is a reality in today’s world economy. Only 50% or collected textiles are reused (by being resold or upcycled for the same type of usage) and 50% are recycled (into products of lower value or raw materials).

There are entire debates going on about the reuse of clothes and where do they actually go once donated to charity shops or collected by municipalities, but we will leave this for another time, to focus on the actual recycling process.

It’s all sorted!

The identification of good quality post-consumer textiles (discarded garments, household items, vehicles), as well as correct segregation of post-industrial waste (any excess material created during the steps of material and product manufacturing, e.g. selvage from weaving, fabric from factory cutting rooms) are key to both obtaining the most commercial value out of textile recycling, as well as enabling better processing into potential new raw materials.

The development of more advanced sorting technologies can address this issue. In the early 2000s The European Union, in cooperation with a Dutch company have been investigating a technology called Identitex. This was based on NIR spectroscopy, which basically means identifying the composition of the garment using infra-red rays, with no or little preparation of the samples. Identitex was proven successful in on a small scale and required further development to be applied industrially. A more recent technology called Fibersort is being trialled, which will allow large-scale NIR sorting of garments.

Here is a video of how it works.

So let’s talk recycling, what actually happens?

The Holy Grail for textile recycling is turning waste (be it pre or post-consumer) into new fabric, in an environmentally friendly process that will not require new raw materials being used in the production process, will not use too much water and will not release harmful chemicals into nature. Unfortunately, we’re still far away from that.

The most common recycling method used is mechanical, which physically breaks down the textiles and reprocesses them into new materials, usually of lower quality and value. Chemical recycling, i.e. breaking down materials at a molecular level and obtaining new materials through chemical processes can result in better quality materials, but technology is not yet sufficiently developed to make it feasible at an industrial scale. If you are interested in the very detailed processes for all recycling methods, have a look here (opens a PDF doc), but be warned it’s quite technical.

Source Wikimedia

Mechanical recycling:

Once pre or post-consumer textile waste has been earmarked for recycling, it needs to be further segregated by type of fibre and colour. Most suitable for mechanical recycling are protein-based fibres (wool, cashmere) and plant fibres (cotton). They are often separate by colour as it will make dying of the recycled material less likely, thus saving water, energy and chemicals being used.

This is what mechanical recycling entails:

  • Carding: pulling fibres into parallel alignment to form a thin web
  • Combing: shorter fibres and impurities are removed
  • Roving: the sliver is pulled out to a thinner strand and given a slight twist
  • Spinning: the last process in yarn manufacturing. Yarns are wound into bobbins, ready for weaving or knitting
  • Weaving or knitting: 2 different ways to turn yarns into harder or softer fabric. It is in this phase that the resistance of the thread is crucial, the shorter is the fibre, the thicker the thread will be.

Recycled cotton is most suitable for denim (Image source: Wikimedia)

Recycled cotton and wool fibres are shorter than virgin ones and that is why they are harder to spin into yarn and therefore require additional fibres (either virgin or synthetic) to enable processing. Currently, no more than 30% of recycled content is commonly found in recycled cotton materials. Usually, recycled cotton gets used in denim, as the thicker yard is suitable for a thicker fabric. Recycled wool is often used as weft yarns on products that have cotton warps. Technology is advancing every year, so dependant on the manufacturer, less and less virgin wool is needed to obtain high-quality yarns and fabrics. However, 100% recycled wool of acceptable quality for high street retailers can be achieved with difficulty and will remain for the time being in the realm of home knitters who can unravel and knit again to reuse the ready-made yarn.

Chemical recycling:

The best candidates for chemical recycling are PET and other types of polyesters. It is quite common nowadays to get fibres out of recycled plastic bottles, especially fleece and other materials used in outdoor equipment. A well known outdoor apparel company has developed a closed loop recycling scheme for their own products for customers who have purchased one of their polyester garments can bring them back to be recycled once they are worn out.

 

Chemical recycling of cellulose-based textiles:

You are probably already familiar with rayon or viscose, which are fabrics made from the chemical processing of tree cellulose. The manufacturing process poses environmental concerns, because of the heavy chemical processing and sometimes the provenance of the wood, but there are companies who have developed eco-friendlier processed (like Tencel).

In 2014, a Swedish company has revealed a new technology that allows them to process any organic material into new fibres and have presented the first garment made out of the resulting material. They say that even the synthetic materials can be recovered and recycled in a similar process to PET bottles. They also claim that the recycling process is cleaner than regular viscose manufacturing from raw materials. Read more in this Guardian article.

Recycled cotton dress (Source: the Guardian)

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Conclusions? Technology is developing, but we are still years away from the industrial scale, eco-friendly chemical recycling that will produce raw materials of the same quality as virgin ones. In the meantime, the sentiment is that designers need to focus more on design for disassembly, thinking not just about the fashion-ability and immediate use, but also how the garment will be disposed of at the end of its useful life. Also, as consumers, the key is to increase the use we get out of each garment, by reusing, sharing, upcycling the clothes we have and making carefully considered decisions about new garments we bring into our wardrobes.

Happy Sustainable Tuesday!

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6 comments

    1. Thank you! Glad you enjoyed it! I know you read these articles, is there anything you would like me to cover in the future? I’m just banking ideas for next posts :).

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      1. Great question. The issue that seems to concern much of my work is not just what the total impact of sustainable development is, but who wins and who loses i.e. will the total environmental impact be lower but will it conversely lead to greater poverty for the poorest people.

        Gender is also clearly a big topic at the moment with International Women’s Day last weekend. For example, when Rana Plaza, the garment factory in Bangladesh collapsed over 1,100 people were killed – 80% of these were women. Most of these women were illeterate and forced to work in terrible conditions. There’s a really good article here about gender and the garment factory set up http://harvardjlg.com/2013/09/gender-and-garment-work-the-rana-plaza-disaster/

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      2. Very good points, Lesley! Unfortunately, not sure my knowledge extends as far as to cover such intense (an controversial) topics. Thanks for the link.

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      3. Ha ha, no, wasn’t saying that at all! Very good points and defo interesting. Should probably investigate more. I guess I’m a bit wary of being too controversial on a little sewing blog, ha ha. Do you also work in the field?

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