About 550 kg of clothes from the Formació i Treball Foundation clothing bins have been analysed in the first study to ever characterise the fibres that make up T-shirts, shirts, coats, trousers, jackets and other kinds of clothing that are dumped in textile collection bins. The study has been conducted by the Terrassa Institute of Textile Research and Industrial Cooperation (INTEXTER) of the Universitat Politècnica de Catalunya · BarcelonaTech (UPC) and student Beatriz Rodríguez, from the Terrassa School of Industrial, Aerospace and Audiovisual Engineering (ESEIAAT), with her bachelor’s thesis directed by INTEXTER director and ESEIAAT professor Enric Carrera. The work is part of the report Análisis de la recogida de la ropa usada en España (Analysis of the collection of used clothing in Spain), prepared by a Cáritas cooperative, Moda-re, and the consulting company LAVOLA. The report was presented at the 15th National Conference on the Environment (CONAMA), which was held in Madrid in May-June 2021.

According to INTEXTER researchers, of all used clothes from the bins, 62% are reusable and 37% are recyclable. The study concludes that the most common fibre is cotton, with 50% in recyclable clothes and 60% in reusable clothes. Polyester follows, with 30% in both types. Therefore, cotton and polyester account for about 80% in recyclable clothing and 88% in reusable clothing.

Acrylic fibres account for a much lower percentage. The study shows a large difference between recyclable clothing (12.4%) and reusable clothing (3.1%), because clothing made from these fibres is the most readily deteriorated.

The characterisation has been possible through an innovative methodology based on crushing garments and standardising the mixture by means of two steps: automatic carding and analysing the resulting webs using the standardised chemical methodology. The result allows to determine the composition of textile products, including the standard moisture regain of every fibre.

Focusing on cotton and polyester
According to INTEXTER director Enric Carrera, “in light of the analysis, we can say that the recycling strategy of post-consumer textile waste should focus on recovering and reusing 80% of the predominant fibres, namely cotton and polyester.”

The study also includes an analysis of the fibre composition of clothing on the websites of major brands. A total of 701 garments were analysed, corresponding to the first 30 items in 6 major categories (T-shirts, jumpers, jeans, underwear, socks and shirts) at Zara, H&M, C&A and Mango. In this case, the anaysis does not include jackets or coats.

The analysis reveals that 66.8% of garments contain mixed fibres, which significantly limits their recycling potential. Only 37.3% of the garments studied are 100% made with a single fibre. 

As for home textiles, 361 items were analysed, corresponding to the first 20 items in 4 major categories (sheets, towels, tablecloths and curtains) at Ikea, Zara Home, H&M Home, 10xDIEZ and Carrefour. Unlike clothing, home textiles are predominantly made of a single material. The most common fibres are cotton, polyester, linen, viscose and lyocell, in that order. Sheets and towels are mainly made from 100% cotton, whereas tablecloths and curtains from 100% polyester, although binary mixtures of cotton and polyester or cotton and linen are also used.

Extending the life of garments
How much would we reduce our environmental impact by reusing used clothing? According to Carrera, “if we could double the lifespan of garments, we would be reducing the fashion industry’s greenhouse gas emissions by 44%. Extending the active life of clothing by just nine months would already reduce carbon, water and waste footprint by 20-30%. An increase of 10% in second hand sales could save 3% of carbon emissions and 4% of water, according to data from the report Valuing our clothes: the cost of UK fashion, published by WRAP in 2017.”

The UPC’s INTEXTER has carried out an extensive bibliographic review of existing studies on how much CO₂ is saved by reusing clothing. It has concluded that reusing 1 kg of clothing saves 25 kg of CO₂, unlike EU estimates so far, which suggested only 3.169 kilos. Access to the report by Moda re- (Cáritas) and LAVOLA.