Many have probably heard of merino wool, but what exactly is so special about this fiber and what are its sustainability implications? Suston provides a primer.

Why is merino wool so high in demand?

Merino wool is the natural superstar among functional materials: Soft and elastic, non-itchy and odorless, warming in the cold and comfortable in the warm, lightweight and moisture-regulating. And as a natural fiber, it is a renewable raw material that is biodegradable. These properties make merino wool the first choice for many outdoor brands when it comes to fabrics for functional shirts and baselayers.

Why is merino often mixed with other fibers? How sustainable are these merino blend materials?

There are various reasons for mixing synthetic or cellulose fibers with merino wool. Especially for sportswear, this improves both drying time and moisture management. The fibers absorb less liquid and allow it to evaporate more quickly. At the same time, merino blend materials are more durable and ensure that the garment keeps its shape longer and is easier to wash. Costs also play a role. Man-made fibers are usually cheaper and more readily available than high-quality merino wool – which is consequently reflected in the prices.

Last but not least, sustainability arguments also speak in favor of a mix: Here, the increased longevity of the material is a particularly important aspect, as it reduces the need for new purchases and thus the consumption of additional resources. Cellulose fibers are also characterized by the fact that if they are not chemically treated, they are biodegradable and can be returned to the natural cycle just like wool. Moreover, compared to other fibers (e.g., cotton or polyester), their production usually requires less water and energy. If the pulp is obtained from wood residues or, as in the case of Tencel, from sustainably managed forests, this can have an additional positive effect on the ecological footprint.

Does it matter where the fibers come from?

In the case of merino blends with synthetic fibers, the sustainability question depends on whether the synthetic is newly obtained from fossil resources or from recycled materials. Polyester, for example, is basically a completely and easily recyclable material that can be recycled and made into new textiles in many places around the world. There is still a long way to go to a well-functioning infrastructure for recycled polyester. But compared to merino wool, which comes mainly from New Zealand, Australia and South America, the transport distances are usually shorter. The disadvantages of merino blend materials with polyester or nylon are that they are neither biodegradable nor can they be easily recycled. The burden of microplastics, which enter the environment and ultimately the oceans during production, use and disposal, is also greater here.

Finally, for a sustainability comparison, the conditions under which the merino wool is obtained must also be taken into account: Does it come from more sustainable farming practices where there is both careful management of pastures and animal welfare (keyword mulesing)? Are environmentally friendly processing and dyeing methods used? Here, it’s important to keep an eye out for certifications such as the Responsible Wool Standard (RWS), the Global Organic Textile Standard (GOTS) or Cradle to Cradle, which can help direct consumers to lower impact alternatives.

Learn more about wool’s sustainability profile here.

Lead Illustration: Nadia Nörbom