Mechanical vs Chemical recycling

Textile recycling has been a hot topic in the last few years. We have increasingly become aware of the harm a throw-away mindset can bring to our earth and resources. Yet, only 1% of collected clothing is recycled into new garments. To become future-proof, we have to think about end-of-life solutions for garments. But what does “recycled materials” mean on the label of your jeans? And what recycling process can be used?

Why should we recycle our clothes?

Recycling textile offers many environmental benefits. Most thrown-away garments end up in a landfill. Laying there, the textile slowly decomposes, which generates greenhouse gases. On top of that, toxic chemicals and dyes can leach into our groundwater and precious soil. Recycling our clothes could keep garments from ending up in those landfills. Recycling textile also reduces the consumption of energy, water and other resources. With recycled items, there is a decrease in demand for dyes, as the recycled fibres may already be coloured in just the right shade. Enough reasons to bring recycling into season!

Mechanical textile recycling

There are two different approaches to textile recycling: mechanical and chemical. The goal of mechanical recycling is to return a piece of clothing back to its basic state: fibres. Before the garment can be shredded, it has to be separated by colour and material. Mechanical recycling is used best for natural mono-fibre fabrics like 100% cotton.

Before garments can be put in the shredder, all parts of the garment that cannot be used are cut off, like metal accessories, like zippers or buttons, are removed. The fibres are then disentangled and aligned in a carding process. The aligned fibres can then be spun to make yarn. 

Mechanically recycled fibres are shorter than virgin fibres and are therefore mixed with virgin fibres with a long fibre length to make sure the final product is of quality and long-lasting. That is why most of our jeans, made with post-consumer recycled denim, do not yet contain more than 20 or 30% recycled cotton. But a lot of innovation is pushing this number.

"Innovations spark hope that it might be possible to use chemical recycling for all compositions in the future"

Chemical textile recycling

Chemical recycling allows for your entire garment to be reused. In chemical recycling, your old garments are broken down to the molecule level: the so-called monomers. For this, the textile is dissolved in a chemical bath. After this process, the monomers can be bonded to rebuild them into new yarn. The technique is quite similar to the process of creating man-made fibres, like viscose or Tencel. 

Chemically recycled natural fibres, like cotton and linen, result in recycled man-made fibres. The output products are frequently of the same quality as their virgin counterparts, with no physical qualities lost due to the recycling process. But you can not chemically recycle cotton or linen back into cotton or linen. Synthetic fibres do not have this problem.

Chemical recycling is still in the early stages of development. Some promising innovations make it possible to separate cotton and polyester fibres chemically. These sparks hope that it might be possible to use chemical recycling for all compositions in the future. But only time will tell. 

An example of a chemically recycled fibre is REFIBRA™. This Lenzing technology upcycles cotton waste streams into renewed fibres. The recycled cotton pulp is added to certified wood pulp and used to produce new Tencel Lyocell fibres. This way, the Refibra technology allows a second life for pre and post-consumer cotton waste.

What is the difference between mechanical and chemical textile recycling?

Both methods clearly have their pros and cons. Mechanical recycling is already used for over a decade and is readily available for brands. It’s also cheaper than chemical recycling since it is still in the innovation and investing phase. It will take time before the whole fashion industry can use it. 

Chemical recycled fibres are of higher quality. Mechanically recycled fibres will get shorter and shorter each time you recycle them. On the other hand, chemical textile recycling is chemically intense. So we have to make sure that we handle those chemicals correctly. But chemical recycling is our biggest hope for all blended fibre garments in our closet. They both bring different solutions to the table. If we want to strive towards a circular future, we will need both to co-exist beside each other. 

A circular future

But recycling is not the only thing we have to focus on for a circular future. Circularity starts with the design of a garment and the selection of materials. Products need to be made to last to keep them out of landfills. We should try to use our clothing as long as possible before they reach their end of life. But when they do, they should be made of easily recyclable materials to give them a second chance in life.

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