While soy fibre is still a relatively unknown choice for textile production, the first investigations into this fibre already took place in Japan during the 1940s and in the US in 1945. But even though the production was a success, the fibre was never commercially produced. The reasons for that included the rise of petroleum, which - due to its low processing cost - became one of the main raw materials used for synthetic textile production. But with the growing amount of environmental concerns and the demand for more sustainability, the interest in alternative fibre production, such as soy fibre, has also started to increase.
Soy fibre is made from the by-products of soy processing and tofu manufacturing. It is considered a man-made cellulosic material, which means that it has to undergo some chemical "manipulation" in order to be turned from a plant into yarn. One positive aspect is that the chemicals which are used during the production process of soy fibre are mostly re-used, making it almost a closed-loop production. In order to produce soy fibre, the proteins within the soybean are broken down by exposing them to heat, alkalis or enzymes, and are then filtered and spun into long strands. In some cases, formaldehyde is used as a cross-linking agent in order to lengthen the fibres and to increase the fabric's crease resistance. If this is the case then the production process is of course neither environmentally-friendly nor safe for garment workers, considering that formaldehyde has been classified as a probable human carcinogen. In order to produce soy fibre in a non-toxic way, the cross-linking should instead be carried out with reagents that do not contain any formaldehyde.
Soy fibre has a variety of positive attributes in comparison to other materials. First of all it has a very soft texture and is often compared to silk - some might even know it under the name of "soy silk". At the same time, it is considerably cheaper than silk, very durable and easy to care for. Fabric made from soy fibre has better absorbent qualities than cotton and is also more breathable. It has an ideal mix of mechanical properties, combining the qualities of natural fibres (e.g. moisture absorbance, permeability, softness) with those of synthetic fibres (e.g. good anti-crease performance and short drying time). Soy fibre is also good for the skin, considering that it contains 18 different amino acids that are beneficial for the human body. It is made from a cheap resource that is widely available, and therefore relatively inexpensive to produce.
But besides its great mechanical properties, there are also some disadvantages of soy fibre. The majority of soy (around 70%) is currently grown in China, where the use of genetically modified soy is very common - an issue that certainly has to be taken into account when trying to assess the sustainability of this fibre. In addition to that, high amounts of water and pesticides are needed for the cultivation of conventional soy. It is also well-known that rainforests are cut down in order to grow soy, which in return leads to a rapid environmental change and habitat destruction. However, around 75% of the total soy production is actually used for animal feeding - which means that there is an urgent need for change in our livestock farming system if we want to reduce the impact of soy cultivation. Soy fibre production on the other hand is simply making use of a by-product which would otherwise go to waste.
But yet again, each producer has their own production methods, and with the lack of clear definitions or certifications it is quite difficult to classify soy fibre as a "sustainable" or "unsustainable" fibre choice. But since it is made from a by-product, the manufacturing of soy fibre is naturally using up less resources than other fibres. So as long as the auxiliaries and additional agents used during the production process are environmentally friendly, soy fibre can indeed be considered a more sustainable option than synthetic fibres or conventional cotton, which are both relying heavily on the use of natural resources such as water and oil.