We have a soft spot for sheep. For many, sheep are symbolic to New Zealand culture with the rearing of sheep being the backbone of the economy for many years.

Sheep farming was established in New Zealand by the 1850s and for several decades wool accounted for more than one third of New Zealand’s exports by value, with the sheep population peaking at just over 70 million in 1982.

This number is significant when compared to New Zealand’s human population of 5 million. By 2020 sheep numbers dropped to 26 million following a decline in profitability compared to other types of farming, particularly dairy.

While also farmed as a food source, today’s article focuses on sheep wool and its environmental attributes.

Image: Tim Marshall

Wool is a natural and renewable resource and as long as our beloved sheep are eating our tasty green pastures they will always produce wool. Wool has amazing properties that make it ideal for many applications from home furnishings to underwear.

Cotton and synthetic fibres are currently the most commonly produced fibres globally, however, their performance and environmental benefits do not compare to wool.

From Wool to Yarn

The wool clip (the total yield of wool shorn during one season from the sheep) is sent to the scourers where it is cleaned and dried before being spun into yarn. The yarn is then sent to the textile manufacturer where many different processes are involved.

The yarn is wound onto dye cones to be dyed the required colours. Next the yarn is warped onto beams which are threaded through the loom, allowing the weft yarn to run across the warp and create a woven fabric.

The fabric is then inspected, washed, and dried. Very few chemicals are used in the processing, typically only water and heat.

Images sourced from interweave

Images sourced from interweave

Environmental Benefits of Wool

Wool is part of the natural carbon cycle. Many textiles and fibres are made from carbon-based products but only some, such as wool, are made from renewable atmospheric carbon. When wool is discarded it will naturally decompose into the earth over months or years, slowly releasing important nutrients back into the soil which fertilise the earth.

How does wool biodegrade?

All materials from animal and plant origin are able to decompose through the action of living organisms, such as fungi and bacteria.

Wool is composed of the natural protein keratin, similar to the protein that makes up human hair. When keratin is naturally broken down by microorganisms the products do not pose any environmental hazard.

How long does wool take to decompose?

Wool biodegrades readily in as little as three to four months; however, the rate varies depending on soil, climate and wool attributes.  This process releases key elements such as nitrogen, sulphur, and magnesium back to the soil, which can be utilised by growing plants.

What are the best conditions for wool to biodegrade in?

The unique outer structure of woollen fibres (keratin) are tough and water-repellent making them an extremely resilient and durable fibre in normal conditions. However, woollen fibres will easily biodegrade in humid conditions and if buried in soil, fungal and bacterial growth produces enzymes that will digest the wool. 

In comparison, cotton takes at least five months to biodegrade and while polyester fibres will eventually break down, it does take many decades.

Wondrous Wool – The Positives 

  • Uses less energy and water than other fibres to produce
  • Rapidly renewable resource
  • Abundant local sources available
  • Sheep can graze on dry land
  • Holistic sheep farming practices can positively impact degraded land
  • Fibre is used in its least processed state
  • Able to absorb and retain volatile organic compounds (VOCs) from the air more rapidly than other fibres, helping to improve indoor air quality
  • Great for sound proofing by dampening or absorbing sound
  • Naturally fire retardant and antistatic
  • Durable with high abrasion resistance
  • Biodegradable, reusable, and recyclable

Reuse Of Wool

There are plenty of ways to reuse wool. From charity shops to clothes swap schemes, there is increasing demand for vintage woollen garments. 

The key thing to remember is the longer a garment or product is used, the more value is gained from the raw materials that went into making it. 

Recycling Wool

The same theory applies to recycling wool items. When the same wool fibres are put to further use whether that be for fashion, technology or textiles for instance, the environmental impact from those fibres is lessened.

There are three main routes for recycling wool:

  • The closed loop system – A mechanical process that returns garments to the raw fibre state and turns the fibre into yarn again, to produce new products (particularly suitable for knitwear).
  • The open loop system – The wool from previous products becomes the basis for a new industrial product, such as insulation or mattress padding.
  • Re-engineering – Getting creative, companies recycle old or unsold items into new products, like making a bag from an old woollen jacket, or using production waste such as trimmings to make other items. Wool is valuable and very little goes to waste.

Wool Innovations Within the Textile Industry

The exciting innovations in wool processing technologies mean the creation of more efficient and environmentally friendly processes in yarn development, knit and weave manufacturing, and dyeing and finishing. 

Traditionally used for synthetic fibres, new technologies allowing digital printing on woollen fabrics are paving the way for creative design opportunities. To digitally print fabrics, coloured dyes are applied simultaneously in varying concentrations to a prepared surface through inkjet technology, producing intricate designs with infinite possibilities.

Innovative new products are also popping up in different industries such as fashion, sports, footwear, interior, protection wear and automotive industries. Including woollen denim, footwear, facemasks, and velvet.

Thanks to James Dunlop for this great article.