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How The Outdoor Clothing Industry Mimics - And Modifies - Nature To Keep Us Warm

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Dr. Melanie Windridge

When temperatures drop in winter, you might spare a thought for the many animals that spend their time outside, but can’t layer up with warm winter clothing like we can.

But you needn’t worry too much. Most animals have lived under the same conditions for millennia and have evolved to deal with their environment. Birds have evolved soft downy feathers for warmth beneath their tougher outer feathers; Merino sheep have wool which helps them survive scorching summers and freezing winters.

Humans, however, like to move around and explore. We leave our cosy homes for a few days to hike in the Scottish mountains, or for a few months to summit Everest. We need different clothing materials for different environments. A huge, research-intensive industry has developed to serve this human desire to discover our world. Materials scientists in this outdoor clothing industry often look to the animals for inspiration.

Learning from our feathered friends

By far the best material for warmth-to-weight ratio is ‘down’, the layer of fine feathers closest to the body of many birds, including ducks and geese. These are springy and create clusters which form air pockets within and between the feathers. As anyone with double glazing knows, air is a great thermal insulator. Heat energy is transferred by molecules colliding with each other. In air, molecules are spread out and don’t collide frequently, so heat is transferred slowly. In a down coat, the warmth generated by the body stays trapped inside.

Scott van Daalen

But down has a major disadvantage. If it gets wet, it clumps together and loses its thermal properties. It’s still pretty useful if you are summiting Everest, where any precipitation falls as snow which is big enough that it does not penetrate the jacket’s outer layer. But on a drizzly day in the Peak District, down is almost useless.

Some climbers also dislike down for ethical reasons. Some is indeed produced without adequate care for animals, though the Ethical Down Standard guarantees humane treatment and most major manufacturers subscribe. However, vegans still prefer to avoid animal products altogether. Furthermore, the price of down changes regularly as supply fluctuates, representing a business risk for manufacturers which they must price into the products they sell.

Materials innovators have long searched for ‘synthetic down’, which mimics down’s insulating properties, whilst also being waterproof.

PrimaLoft® goes a long way to replicating down. Dr. Alice Coles-Aldridge of the Royal Society of Chemistry explains, “PrimaLoft® combines two types of water-resistant fibre: one down-like fine fibre which is good for trapping air, and one larger fibre which is strong and holds material in shape when it gets wet. It is a great example of how properties of natural materials can be replicated and modified by synthetic materials.”

PrimaLoft® was originally produced as a thick pad of material, which was great for insulation but limited for comfortable clothing. A recent innovation - a collaboration between PrimaLoft® and Montane - is Thermoplume®, synthetic fibres that look and feel like down.

Image courtesy of PrimaLoft®

I recently met Lottie Watkinson, Product Director at Montane, who told me about the innovation. “Thermoplume® is a polyester that is naturally hydrophobic, i.e. it repels water, and has insulative properties even when it’s wet. It is made from loose fibres, as opposed to traditional wadded PrimaLoft®, creating unique structures which work together to trap more air. When it comes to the warmth to weight, ThermoPlume® is more thermally efficient than regular PrimaLoft®. It is also lighter and more packable, because there’s more space in between the fibres that can be compressed.”

“Whilst down is still the gold standard when you are certain of dry conditions, if you’re not sure what’s going to happen with the weather ThermoPlume® is the technology to use.”

Not-so-woolly thinking

This approach of mixing natural and synthetic fibres is behind many of the clothing innovations designed for explorers of the world’s extreme environments.

Merino wool, from Merino sheep, is commonly used in base layers. The fibres are finer than the width of a human hair and their structure allows them to pack together densely. This gives them great heat management properties, keeping heat in during winter and out in summer, and also means they feel comfortable against the skin. However, the material does not last very long, and doesn’t allow moisture (e.g. sweat) to easily escape.

Merino wool is also combined with synthetic materials to benefit from the valuable properties of both nature and science. “Primino® is a combination of merino wool and PrimaLoft®,” says Dr Coles-Aldridge. “The wool retains heat, and the synthetic fibres add durability and create a wicking effect, whereby moisture from sweat is transported away from the body through the fibres – which act like lots of little tubes – to the outside of the garment. This mixture gives a comfortable, fast-drying, moisture-wicking baselayer.”

Watkinson adds: “PrimaLoft® is a particularly exciting company and one of our main partners. They are scientists who are constantly coming up with progressive innovation. One of the latest is an insulation designed so certain microbes want to eat it. It will be fine in your wardrobe, but once it finds itself in landfill, it will biodegrade within a year. A lot of the PrimaLoft® materials already on the market are made from recycled post-consumer polyester”. This plays into a major issue right across the clothing industry, around 300,000 tonnes of clothing goes into landfill each year according to WRAP, a sustainability charity.

Nature and man-made fibres are not in competition, they complement each other. We can get the benefits of both by combining fibres most relevant to our needs. Modern science, combined with thousands of years of evolution, allow us to get the benefit of both worlds, and have led to a range of outdoor clothing materials that keep us safe and warm in even the world’s most extreme environments.