Merino wool, a natural fibre grown by Merino sheep in Australia and championed as a sustainable alternative to synthetics, does not contribute to the issue of microplastics in our oceans, according to new research from The Woolmark Company.
The 'Microfibre Pollution and the Marine Biodegradation of Wool' study found that both untreated and machine washable wool readily biodegrade in marine environments, while synthetic fibres do not.
The issue of plastic microfibres and their harmful impact on the environment has become a growing focus for the fashion industry in recent years. Between half a million and a million tonnes of plastic microfibres are released into wastewater every year from the washing of synthetic clothes, according to Common Objective.
The Woolmark Company’s study compared the biodegradability of both untreated and machine washable Merino wool in sea water with the biodegradability of viscose rayon, polyester, nylon and polypropylene using scanning electron microscopy and energy-dispersive X-ray spectroscopy. All the fabrics were washed repeatedly before testing to reflect a “partial garment lifetime” and the rate of biodegradation was compared to that of kraft paper pulp, a substance known to biodegrade readily.
Machine washable wool biodegrades faster than untreated wool
The Woolmark Company’s report found that machine washable wool biodegrades at a faster rate than untreated wool fabrics and that there was no evidence that treated wool’s polyamide resin coating - which is added to prevent shrinkage - contributed to microplastic pollution.
The report found that untreated wool biodegraded at 20.3 percent the rate of the pulp, while the machine-washable wool biodegraded more than three times as quickly, at a rate of 67.3 per cent - the fastest of all fabrics.
Nylon biodegraded at the slowest rate of the fibres tested at just 0.8 percent, followed by polypropylene and polyester.
The Woolmark Company managing director Stuart McCullough commented in the report: “Our research into wool and microplastics began back in 2016 when we investigated the current state of knowledge concerning microplastic pollution, focussing on microfibres from textiles. This initial body of research began the process of improving methodological development to account for microfibre release during the use phase in the Lifecycle Assessment of clothing.
“This latest scientific study is a significant addition to the body of research investigating the damage certain textiles cause to our environment. Wool has long been heralded the original eco fibre, but concerns had been raised about the machine-washable finish applied to wool and whether it added to the microplastic problem, so we wanted to clarify that issue.
“During these ever-changing troubled times it’s important to consider how well-intentioned consumers can make purchasing decisions that help look after the health of the environment. Choosing natural fibres, such as Merino wool is an important place to start.”
Photo credit: Woolmark Company's Live & Breathe campaign | Stuart McCullough & Chart courtesy of AWI