Fur Technology

How does Feather and Fur Technology work?

Hypothermia kills, so why have feathers and fur evolved?

Evolution has developed some incredible things: the eye, the brain, the immune system - all brought about through the crucible of hard fought survival. So why do animals that live in the harshest environments on earth wear feathers and fur outside of their skins?

Membrane garments act like a waterproof skin. The problem is that the membrane stops breathing when it gets chilled, trapping liquid water inside. This leaves you cold and damp and your membrane clothing system dries slowly.

Animals don’t wear their skin on the outside because fur and feathers have unique properties that prevent water from getting in while allowing condensation to escape. Fur Technology continues to breathe in persistent wet weather and dries incredibly quickly.

There are 4 key elements to garments using Fur (and feather) Technology:

1. The outer fabric acts like the windproof flight feathers of birds

2. The technical inner fur layer faces outwards, directing water away and absorbing the momentum of wind driven rain

3. Durable water repellency, comparable to the natural oils found in feathers and fur, are applied to both layers

4. Detailed design prevents water ingress and allows drainage

Together these 4 elements work in a number of different ways

• Our fabrics have minimal resistance to water vapour on its journey away from the body. Considerably lower than any membrane softshell or hardshell!

• In persistent wet weather, condensation inevitably occurs in the outermost layer, as vapour meets rain. The outer fabric wets out, changing from water hating to water loving, sucking condensation from the inner fur layer and removing it from your clothing system. Cold and wet membrane hardshells and softshells do not breathe in these circumstances and they trap condensation in your clothing system.

• Water that gets into the fur layer drains away towards the outer fabric, keeping your insulation dry. Conventional layering or softshell systems typically use water absorbing or wicking insulation that wets easily, absorbing water!

• Wind evaporates water from the outer fabric, drawing condensation from the inner fur layer. Wind cannot remove water from inside a membrane system because they are impermeable to liquid and evaporation from the outer fabric has the effect of further chilling the membrane, preventing breathability!

• Membrane garments are also prone to puncture and seam tape can delaminate. Our seams are sealed by the technical fur lining and don’t require tape, enhancing breathability significantly.

• FurTech garments are immune to damage by thorns and tears are easily repaired: sew the outer separate from the inner and re-proof. Membrane garments puncture easily and repairs require sealing.

• Membranes are laminated to fabrics or applied as a paste. This stiffens the fabric, often creating a noisy garment. Also, the membrane in the hood muffles sound. FurTech garments are quiet and the hood allows conversation and belay shouts to be heard.

Water conducts heat 24 times more effectively than air!

If just 10% of the air in your insulation is replaced by water its effectiveness falls by more than 70%!

It takes approximately 580 times more energy to evaporate water than to increase its temperature by 1°C?

There are 3 factors that effect evaporation: temperature, humidity and pressure.

Wind increases evaporation by reducing vapour pressure.

Core Temperature is Crucial to Survival

Even animals that survive desert days and nights wear feathers and fur. They use many ways to control their temperature. Birds for example, may spread their flight feathers to allow air to circulate close to the skin.

Our jackets use enormous rain vents (pit zips). These are more effective than vents in conventional waterproofs because they use a single, easy to operate zip to vent directly through the integral insulation to your base layer.

Unlike some other products our pit zips can be used to vent even in heavy rain. The vent is held open automatically by the zip fabric to form cowls at the front and back which prevent water ingress unless conditions are particularly windy or you have your arms raised.

Arm movement helps to circulate air through the vents very effectively.

When climbing with slings, body coils and sack you can save hassle by slipping your arms out of the pit zips and tucking the sleeves back in the jacket or under your sack straps…. particularly useful when trying to get off a glacier before the snow bridges get too soft.

Sometimes it is useful to keep cool by folding up the cuffs a notch, un-zipping the front and fastening the base of the jacket behind your back.

Adding hats and gloves to increase insulation means that you can often avoid changing layers during the day, reducing the faff factor and increasing speed across the ground.

Breathability and venting facilitate evaporation of sweat, which keeps you cool.

Breathability and venting also remove humidity from your insulation, which then works far better when you stop.

How does a conventional 3 layer system work in the rain?

“I remember years ago, slogging up Grisedale Pike in warm drizzly conditions wearing my waterproof membrane over a synthetic base layer. It was pouring down, cold and blustery at the top and I was soon chilled. Pressing on to try and keep warm I was hoping for a break in the weather in order to add some insulation. During a slight lull I quickly stripped my waterproof off and added a fleece. Nevertheless it got soaked and my base layer was saturated. Result: cold, wet and miserable.

Using FurTech in similar conditions I’m a little warm after 15 minutes of hard walking but stay comfortable and protected as conditions worsen with altitude.”

FurTech is Naturally Light

In the natural world everything has a cost and a benefit. Birds even have hollow bones in order to make flight easier and Feather and Fur Technology follows this principle.

FurTech is significantly lighter than a hardshell and hooded fleece with pit zips. We cut out the need for membranes, tape sealing, extra zips and trim.

You may be able to find a lighter waterproof but you will not be able to find a lighter system that can be worn through such a wide range of situations and conditions without the hassle of changing layers. Less hassle translates to faster progress and more enjoyment. Fast doesn’t just mean light, it means hassle free with less need for stops and a reduced faff factor.

In comparison to other softshells, FurTech saves you the weight of carrying a waterproof just in case it rains and removes the hassle of changing. (Also, by putting a hardshell over a wet softshell you can paralyse the hardshells’ breathability.)

FurTech is excellent value when compared to the cost of a high performance waterproof AND fleece or softshell.

“Many people will perceive FurTech garments as only suitable for the cooler months but I even get away with using them in hot wet conditions. In the summer they are useful for changeable mountain weather.

In winter I wear thicker or multiple base layers to broadly regulate my temperature and add a synthetic insulated jacket over the top for stops. A group shelter or clan tent is also useful.”

Andy Davison

biomimicry

Water off a Duck's Back!

Ducks, along with many other aquatic birds, are waterproof enough to float. This ability comes from the combination of feathers, down and excellent water repellency.

But how do they stay comfortable over such a wide range of conditions? The temperature flexability of their insulation is extraordinary, coping with life on the water (water conducts heat about 24 times more effectively than air) and on the wing, where they suffer constant wind chill.

Sea Otters' Fur

Ever wondered about aquatic furry animals and how their fur works? This link describes it well!

Feather Technology

  This site has an interesting diagram of flight feathers and how the fibres lock together for wind resistance (scroll down the page when you get there).

The outer fabric on our FurTech clothing is analogous to the flight feathers of birds or the guard hairs of mammals.

Penguin Feathers

Penguins may have as many as 11 feathers per square centimeter. They are short (about 40mm) and dense and offer good wind and water resistance. The feathers are coated with a water repellent oil secreted from a gland near the tail, similar to ducks.

To aid swimming the feathers are flattened against the skin, partly by muscular control and partly by water pressure. This reduces their buoyancy and improves hydrodynamics. They instantly expand on coming out of the water so that insulation is maintained in the cold air. The compression of the feathers may improve their water resistance.

Amazing fact: An emperor penguin was recorded diving to 540m (1772ft)!

Polar Bears

Polar Bears have been tracked on 100 mile swims!

Their fur is not white, but transparent. This may create a greenhouse effect on cold sunny days to keep the bear warm and may reflect body heat(?) The hairs are hollow to trap still air and are coated with water repellent oil so that water and ice can be shaken off after a long swim. Sometimes they roll in the snow to remove water from the outer fur. The inner fur can remain dry when swimming and the trapped air may offer some buoyancy. Fur on the feet may aid traction and they have built in crampons!

Snow falling on a resting bear adds insulation but sometimes they dig a snow hole for protection.

Their insulation is so efficient that they may not appear on thermal imaging cameras!

http://www.geocities.com/mikepolarbear/warm.html

Head Hair is not the same as Fur

Why does human hair continue to grow? This link explores the difference between fur and head hair.

Which came first, feathers or flight?

A small dinosaur discovered in China seems to suggest that feathers evolved before flight, either for insulation or display purposes. See this link.

Emperor Penguins

David Attenborough presents Emperor Penguins at this link.

Snow Leopards

This video is taken from David Attenborough's Planet Earth series and shows the filming of the snow leopard.

Why don't penguins' feet freeze?

This is the title of a New Scientist paperback which I'd recommend to anyone interested in scientific questions. If you don't want to buy the book have a look at the answer posted here.

This link has a broader description of thermoregulation in penguins.

The Most Breathable Fabric in the World

A spiders web must rank as one of the most breathable and lightest fabrics in the world. But they still get condensation on them!

This is because condensation can form on any surface once the dew point is reached. It is also why feathers and fur have evolved to allow condensation to escape.

Its all about thermodynamics!

The Alpine Chough

Alpine Choughs have been recorded nesting above 6000m!

They can be seen ridge soaring on the summit of Mont Blanc near the end of this video.

Why do camels wear fur?

A camel's thick coat reflects sun light. A shaved camel has to sweat 50% more to avoid overheating! It may be that camels (dromedary) adapted for hot deserts have fur that provides shade and good air flow, creating a better micro climate near the skin. Bactrian camels have two layers of thick fur and survive extremes of temperature.

This link from wikipedia provides more information about camels.

Penguin Feathers in the Wind

Wind chill has a powerful effect on heat loss. Have you ever wondered how animals cope? Especially birds, that naturally endure wind chill when they fly. What about penguins in Antarctic storms, when the wind isn't just coming from the direction of flight?

A study by Jan R.E. Taylor at the Polish Academy of Sciences has shown that Penguin Feathers have increased insulation in the wind!

This seems to be due to the feathers being pressed together, sealing the gaps in between and sealing out the wind. A similar mechanism is likely to occur under water to increase waterproofing.

(Interestingly the report suggests that movement of the feathers underwater may actually reduce drag, allowing penguins to swim faster.)

Beaver Fur

Beavers have a double layered coat: long guard hairs, which are molted in the spring, and short dense inner fur, which mats together into an insulating felt. Beavers use their front paws to spread oil from their cloaca gland onto their coat. This provides excellent water repellency. The guard hairs may look saturated but the inner fur is dry.

Beavers have been re-introduced into the wild in the UK, after they were hunted to extinction for their luxuriant fur.

Coldest Birds

Emperor Penguins regularly endure temperatures of -45'C!

In Vostok, Russia, South Polar Skuas have survived despite temperatures of -89.6'C!

Infrared Zoo

This link shows various animals photographed with an infra red camera.

Desert Animals

Many desert animals wear fur (or feathers). This link details some of the mechanisms they use to keep cool.

In the UK we see birds fluff up their feathers to stay warm but some birds create gaps in their flight feathers so that air circulates close to the skin to keep cool... similar to opening the vents on our jackets!

More on how birds keep cool.

BBC Life Of Mammals: Thermal Tricks

This BBC article succinctly outlines much of the thermal biology of mammals, including behavior. It seems to me that how to get the best out of clothing and equipment is not usually covered by manufacturers, who make believe that their kit does magic.

We hope that the features of the FurTech garments, in conjunction with Shelters, OverShells, various baselayers and other equipment, allow you to tune the performance of your outdoor survival system.

Why don't elephants wear fur?

Obviously elephants live in hot countries... but other animals that live in the heat wear fur: giraffes, zebra, lions!

The size and shape of an animal has an impact on how it loses energy. The more surface area it has, compared to its mass, the easier it loses heat. Elephants have a large mass and comparatively little surface area, because they are well rounded. Large ears are used for cooling.

On the other hand, giraffes have a large surface area compared to their mass.

These concepts are explained in human terms at this link. Put simply, if you are well rounded you will stay warmer than if you are thin and spindly.

Keratin: The material of Feathers and Fur

This link explains an ongoing study into the mechanical properties of Keratin. It appears that fur keratin is different to feather keratin, which is similar to some polymers. Thus the architecture of down may be more significant to its thermal performance than the material!

Thanks to Richard Bonser, Lecturer in Biomimetics and Deputy Director of Research, Reading University.

(FurTech garments are constructed from synthetic materials.)

Homeostasis

Homeostasis is the ability of an organism to regulate its internal conditions. Temperature regulation is an important aspect of homeostasis, exhibited by mammals in the shiver response, sweating or seeking shelter. Feathers and fur are important aspects of homeostasis.

Here's more on homeostasis.

Why don't whales wear fur?

It's cold in the sea... but substantially warmer in the water than exposed to the penetrating cold of an Antarctic winter! The sea temperature stays between -2'C and 10'C and there isn't wind chill underwater! In fact aquatic animals don't have the problem of regulating their body temperatures across such a wide range of conditions and activities as land animals, where sun, wind, precipitation and weather systems can have a much greater effect.

Aquatic mammals don't require great temperature flexibility. For insulation they use a layer of fat (blubber) instead of highly breathable fur (which would eventually become saturated).

It is interesting to note that humans with more body fat have substantially longer survival times in water and tend to "run hot" compared to skinny people. If you have ever stood around on a rainy, windy beach wearing a wet suit you will also understand how much warmer it is in the water and out of the breeze.

Warm and Cold Blooded

The phrases warm and cold blooded have fallen out of favour with scientists as they have begun to understand more about the thermo regulatory systems of animals. Instead warm and cold blooded could be seen as either end of a range of thermo regulatory systems that includes many differences between the animal classes. Please see this link for more detail.

Warm blooded animals maintain their core at a constant temperature regardless of the environment and have evolved systems to generate heat (eg shivering) or cool down (eg sweating). Cold blooded animals have a temperature dependent on the environment. However, some animals previously considered simply as cold blooded use the sun to warm themselves or flowing water to cool down (ectothermy), and others adjust their metabolism (bradymetabolism).

The image above shows a snake eating a mouse! Below is a furry Tarantula on a fur less human hand.

Furry Insects

It isn't just mammals that have fur. Many insects are hirsute. Apart from the obvious thermal properties I wonder if the fur on some insects has other benefits: Perhaps it provides a sort of bristly armour against small jaws, stings and impacts? It may help sense wind and touch? Perhaps in moths it even attenuates sound to reduce the sonar signature from a predatory bat?

Water off a Duck's Back: Cassie's Law

The incredible water repellency of a duck's feathers isn't just explained by the oils from the preen gland. Cassie's Law shows how the submicrometer surface texture increases the contact angle of the droplet with the macro surface to create a superhydrophobic effect.

The Lotus Effect

It's not just the Lotus leaf that has an extraordinary ability to self clean, despite living in muddy water. Other plants, available from your garden center, exhibit the same properties. This is because the surface of their leaves are hydrophobic and water just rolls off, carrying dirt with it.

This is a similar effect to the Durable Water Repellency added to outdoor garments, though some hydrophobic treatments attract oils, limiting their ability to stay clean.

More from wikipedia.

This link includes a diagram of the contact angle and explains the implication of surface roughness for super water repellency.

Clothing Comments In "Winter Skills"

"The outer or hard shell should keep out wind and water, but allow moisture to escape outwards. This is done by using waterproof breathable fabrics of which there are many types. These generally perform best in dry, cold conditions, when warm moist air is more easily transferred out through the fabric. This driving effect is enhanced by a water-repellent coating on the outside that causes water to bead and roll off. A saturated outer fabric means a reduced rate of breathability. Unfortunately this is exactly the type of problem liable to be encountered in poor winter conditions. On cold days, wearing thick insulation means that less body heat reaches the outer layers, so decreasing the driving effect pushing moisture out through the shell."

In fact, when the outer fabric is cold and saturated, membrane garments have virtually zero breathability. This situation doesn't change until the outer becomes warm and dry. This is why animals have evolved to use highly breathable feathers and fur outside of their skins, for optimum performance across a wide range of conditions, even after saturation.

"Winter Skills", written by Andy Cunningham and Allen Fyffe, is the official handbook of the Mountaineering Instructor Certificate and Winter Mountain Leader schemes.

Furry Leaves

Some plants have leaves and stems that are furry. And some of these plants are very water resistant. The preceding photograph shows a very hydrophobic plant with a furry surface. Rain and dew collects like mercury on the leaves and as it evaporates the last drops to go are at the very tips, as if they were adorned with jewels. This may be because these droplets are very spherical and have the minimum surface area, thus evaporating the slowest.

Denier Gradients and Fur

Guard hairs are generally thicker at the base than at the tips as you can see in human hair. When this fur is packed together in a thick coat the change in cross sectional area may encourage water droplets to move towards the tips due to the surface tension of water (aided enormously by shaking). The difference in diameter is similar to the denier gradient employed in our fabrics.

Denier gradients can create directional fabrics that help move moisture away from the body because small diameter fibers are more easily encompassed by water than larger ones. This aids drying of the fabric and is driven by body heat from the inside and wind and sun from the outside. Denier gradient fabrics are also employed on some baselayers for improved wicking.

BioMimicry

The Biomimicry institute promotes the transfer of ideas inspired by nature. Click here for their web site.