Cotton is by far the most commonly used natural fibre for home and clothing textiles. The entire plant can be utilised: seed fibres for making textiles, cotton oil for cosmetics and plant residues as green manure.  Unlike other textile plants such as flax, hemp or jute, the stalks of cotton plants are also processed. However, global production of these bast fibres is much lower, at around 2 million tonnes per year each. Although they can be processed like cotton, they are mainly used for so-called technical textiles in industrial applications rather than the production of clothing. The huge global demand for fabric can no longer be met by cotton. In 1990, the worldwide availability of cotton was 19 million tonnes, which is 49% of the total fibre market. According to the Industrievereinigung Chemiefaser (Industrial Association Synthetic Fibres), the 26 million tonnes of cotton produced in 2020 covered just under 24% of total fibre production worldwide. 

There are synthetic fibres that are based on a renewable raw material – wood. Cellulose regenerated fibres are obtained from cellulose, which is then chemically modified, such as viscose. Even though viscose is chemically identical to cotton fibres, viscose fibres have a wider range of possible fibre geometries (length, crimp, fineness, cross-sectional shape) and can thus be applied more widely. While the production and processing of viscose consumes less energy and water than cotton, it produces toxins such as hydrogen sulphide (H2S) and carbon disulphide (CS2) that are harmful to human beings and the environment. 

There are other synthetic fibres made from cellulose whose production is less environmentally harmful, such as lyocell. The direct dissolving process relies on a non-toxic solvent and works within a closed material cycle. The cellulose for lyocell fibres is harvested from eucalyptus or beech wood. These plants grow faster than cotton and have a high yield per area, which gives them a better environmental footprint. Recent research has also shown that flax, hemp, ­bamboo, banana and soya are also suitable for cellulose pulp. 

Spider silk threads are marvels of nature; they are only a tenth as thick as a human hair, yet ­twenty times stronger than steel and more elastic than rubber. The natural material is extremely suitable for high-tech textiles. The Martinsried-based company AMSilk has developed a biotechnological process to produce spider silk protein on an industrial scale. The company, founded in 2008 as a spin-off from the TUM in Munich, has converted bacteria into cell factories for spider silk protein. The final step of the bioprocess is a white protein powder that can be spun into fibres by machines (see photo on p. 79). Textiles made from these vegan silk biopolymers are not only particularly hard-wearing and skin-friendly, but also completely biodegradable. Sports clothing company adidas has joined forces with AMSilk and produced a sneaker prototype whose upper material consists of Biosteel fibres (see photo p.78). These biotech textiles have also been used in straps by watch manufacturer Omega.

Leather is a durable and versatile material that is used for many everyday objects, such as furniture and clothing. However, leather made from tanned animal hides causes pollution and is viewed with increasing scepticism. Consumers are turning to imitation leather made from pineapple fibre, apple pomace or cactus leather, which are considered to be more sustainable. However, these materials always contain some petroleum-based plastics, such as polyvinyl chloride or polyurethane. Another new alternative are leather substitutes made from fungi which are cultivated on residues from agriculture and forestry, such as sawdust or molasses. The growing fungal network, the mycelium, creates fungal biomass, which can be processed into a material that looks and feels almost exactly like leather. Some biotechnology companies have already started marketing the materials obtained from fungi. adidas for example has produced a prototype of a vegan sports shoe using a fungal mycelium material called Mylo instead of leather. It is manufactured by the US company Bolt Threads from California. The Leipzig-based start-up ScobyTec has also developed a biotechnical process in which microorganisms produce bacterial nanocellulose (BNC), a nonwoven fabric that can be used instead of leather.

There are also some bio-based innovations in leather tanning. Chromium salts, which are harmful to the environment and health, are increasingly being replaced by plant-based tanning processes. One example is Rhubarb Technology, a start-up that has extracted a substance suitable as a tanning agent from the roots of rhubarb plants. wet-green, a company from Reutlingen, makes a tanning agent from olive leaves, which was developed in collaboration with N-Zyme BioTec. Textile dyeing is also turning to plant-based raw materials, using traditional plant dyes in order to make textile dyeing more sustainable. Dyeing plants such as madder, reseda, bluewood, gardenia and jasmine flowers have proven to provide effective dyes. In a project funded by the BMEL, two vegetable dyes for printing on silk and modal fabrics were developed. The spring 2019 collection of hessnatur already featured two silk blouses that had been printed using the colour pastes developed in the project. 

According to the Bundesverband Sekundärrohstoffe und Entsorgung e. V. (BVSE - German Association for Secondary Raw Materials and Waste Disposal), approximately one million tonnes of clothing end up in clothing banks every year. Clothes that are no longer wearable are usually turned into cleaning rags or painter’s fleece. However, a sustainable circular economy in which textile fibres are recycled has not yet been created. Researchers at Fraunhofer IAP have found a way to produce a high-quality fibre from used cotton textiles. This had previously not been technically feasible because most clothes are made of mixed fibres. The researchers have developed a process for filtering cellulose from the cotton to create a viscose filament yarn consisting of 100% cellulose. The quality of these recycled fibres is comparable to wood-based cellulose regenerated fibres and has the same quality as viscose fibres.

Knowing each type of fibre and understanding the fibre composition is a prerequisite for recycling textiles. The DiTex project  is testing the quality, resources and sustainability of workwear and towels made from recycled fibres as part of a pilot project funded by the BMBF. For this purpose, the textiles were equipped with an intelligent label that stores parameters such as material mix, fibre origin as well as washing and recycling cycles. This allows tracking and analysing the complete life cycle of the textiles, including all environmental aspects.