Wool
8-25 usd/kg
Wool and hair are insulating and protective in nature. For millennia, these qualities have been transferred to clothing, interiors and construction in the form of woven, knitted and nonwoven fabrics. Ranging from coarse to fine, soft to stiff and curly to straight, wool and hair have many desirable properties. For example, water resistance, moisture absorption, fire resistance (it self-extinguishes) and natural colour variation.
These fibres are made up of keratin, a fibrous protein. It is the key structural material in scales, feathers, horns and claws, as well as wool and hair. It becomes softer and more flexible when wet, losing some of its strength. This returns when the fibre dries, but means these fibres are vulnerable to certain types of environment and washing. An advantage of this weakness is that wool can be felted into dense fabric that dries to form a tough and insulating structure.
Animal fibres account for only around 1.5% of global textile production, and wool from sheared sheep dominates this (1.3%). There are many other types of hair used in much smaller quantities worldwide, such as goat (cashmere and mohair), rabbit (angora), camel, llama, alpaca, vicuña, guanaco, quiviut (muskox) and yak.
The high carbon footprint of wool fibre production is dominated in part by rearing sheep and the associated feed and methane production. Methane is a more potent greenhouse gas than CO2 and therefore gives a higher contribution to climate impact per kg. Scouring (washing) is energy and water intensive. Only around half of a fleece is usable for fibre production. The rest is made up of contaminated fibre, dirt and lanolin, which must all be removed.
Sheep are sheared in the spring when they would naturally start to moult, which helps to protect them from overheating and insect attach. There are several synthetic fibres that offer an animal-free alternative to wool. The most common are acrylic fibre, produced from polyacrylonitrile (PAN), and regenerated cellulose fibres such as acetate, viscose and lyocell.
There isn’t a lot of data for other types of hair, but it can be assumed these will not be better, because the fibre yield per animal will be less than for sheep. However, farming practices vary greatly and may be less intensive, more humane and inherently organic.
Aside from the significant environmental impacts of production, wool has many advantages in use. It is biodegradable, compostable and plastic-free, so fully circular by nature (as long as it is not full of chemical enhancements). It does not produce microplastics like synthetic fibres, which are becoming a significant problem in the environment. And in use it can be argued that wool doesn’t need as much washing, and outlasts synthetics equivalents in garments and flooring alike.
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Sustainability concerns
Sourced from animals
Llama and alpaca have been selectively bred like sheep and goats to produce a very fine and uniform fleece useful in textiles. Guanaco and vicuña, on the other hand, remain wild. While not produced in such large quantities, and so relatively expensive, their hair has some advantages over wool. It is hollow, called medullated, which means better thermal regulation in both cold and warm weather clothing.
The fibres are smoother and so do not grip together as well as sheep wool. This helps to prevent felting, however, it means the yarns must be twisted more tightly to stay together and this can result in a stiffer hand. Blending them with high quality wool produces a more balanced fabric that will drape more loosely.
The fleece does not contain oil or lanolin, which helps to keep it lighter, hypoallergenic, and means less intensive sourcing (washing) is required in processing. Combined with the natural colour variation, which reduces the need for dyeing, this helps to minimise the negative environmental impacts of using animal fibre.
The fleece is made up of two distinct types of hair: soft insulating undercoat and long protective guard hairs. The undercoat is typically the most highly priced part of the coat, because animals that have a higher proportion of undercoat tend to produce the most luxurious fabrics. While llama tends to be a little coarse, alpaca produce the finest and softest fibres.
Alpaca fibre comes mainly from two breeds: Huacaya and Suri. Huacaya fibres are crimped, elastic and resemble sheep wool. Suri fibres tend to be straight, long, soft, entangled and likened to cashmere.
