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How Waterproof/Breathable Fabrics Work

HOW DO WATERPROOF/BREATHABLE FABRICS WORK?

HOW DO WATERPROOF/BREATHABLE FABRICS WORK?

Until the latter stages of the 20th century, the term “waterproof/breathable” didn’t get a great deal of circulation in hiking circles. Upon its introduction, it was viewed with suspicion — how, after all, could a fabric let anything out without simultaneously letting other stuff (i.e. rain) in? Fast forward to the enlightened days of the early 21st Century and you can't escape it appearing everywhere in the clothing aisle of your local outdoor store, so much so that a few of us are inclined to wonder how in the heck the magic is done.

Check out our hiking clothing guides:

For most of us, taking the wonders of our waterproof/breathable backpacking rain pants at face value is good enough, but learning a little about their workings and mysterious ways can go a long way towards helping us choose the best products out there for our activity type and MO in outdoors.

Senior Man On Hike Through Beautiful Countryside in fleece jacket

Below, we’ll break down the secrets behind the functioning of the most breathable fabrics that are also waterproof into bite-sized, easily digestible chunks, starting with a brief overview of what these products are and do before delving into a dash of science.

What is a Waterproof/Breathable Fabric?

To offer a broad definition, a waterproof/breathable fabric (abbreviated to “WP/BR”) is one that, to varying degrees, combines both the ability to prevent external moisture (i.e. rain and snow) entering while permitting or actively encouraging internal moisture (i.e. sweat) to seep outward and evaporate on the fabric’s surface. This is similar, but subtly different to water resistant clothing which is usually only uses a DWR coating (What's the difference between water resistant and waterproof you ask?).

The term itself is, in fact, something of a misnomer, with the “fabric” in question most often composed of a duo or trio of very thin layers that would make the plural — fabrics — more accurate.

Breathable waterproof fabrics first hit the shelves in the late 1970s with the introduction of Gore-Tex’s (then) groundbreaking laminate membranes. These days, Gore-Tex no longer rules the roost of waterproof breathable fabrics as comprehensively as is once did and many other forms of WP/BR product — eVent, Sympatex, MemBrain Strata, HyVent — are now making huge inroads into Gore’s one-time monopoly

Waterproof/Breathable Fabrics - The Science

The magic of waterproof/breathable fabrics is achieved by using either a laminate membrane or a liquid coating on the interior of the garment:

Laminates  

The most common forms of laminate membranes are made with either expanded polytetrafluoroethylene (or “ePTFE”, a.k.a. Teflon), polyurethane (PU) films, or polyester films.

This membrane usually measures somewhere between 7 and 30 microns thick and is bonded to the interior of a garment's outer like a second skin. To give you some idea of scale, one micron is one-millionth of a meter and a human hair measures in at around 100 microns.

woman hiker photographer

ePTFE membranes contain a multitude of microscopic pores (W. L. Gore, the maker of Gore-Tex, estimates about 9 billion per square inch) which are responsible for the fabric’s ability to resist penetration by rainwater while simultaneously allowing sweat vapor molecules to escape outward to the fabric’s surface.

It may seem counter-intuitive to make a waterproof garment porous, and the instinctive line of thinking is that this abundance of microscopic holes/pores should make an ePTFE sure to leak, but these membranes work because said pores/holes are far smaller than even the tiniest raindrop but big enough to let water vapor molecules (which are much smaller) seep through.

backpacker wearing 3 layered clothing system

Additionally, ePTFE membranes possess what in scientific lingo is known as “low surface tension," meaning the membrane can only be penetrated by other fluids with an equally low surface tension. Liquids with a “high surface tension," such as rainwater, pool together into beads or globules on the membrane’s surface and slide off instead of penetrating or saturating the membrane.

In the case of Gore-Tex WP/BR fabrics, the ePTFE membrane is attached to an incredibly thin protective polyurethane (PU) film to create what is known as a bicomponent laminate. This secondary layer protects the ePTFE from contaminants such as sunscreen, body oils, or insect repellent, which can cause a membrane’s efficiency to deteriorate with time.

Water vapor transfer is permitted by making the polyurethane film hydrophilic (meaning it attracts water) with water-attracting chemicals or by using other hydrophilic materials such as polyethylene oxide.

Kieran Mugshot

Sweat molecules are drawn to the hydrophilic film in a process known as adsorption and eventually seep through as a result of the differential pressure on either side of the film. In a nutshell, the hot air and vapor on the inside of the jacket move towards the cooler and drier surface of the jacket, jumping from one hydrophilic polyurethane molecule to the next in a microscopic but very intricate and longwinded game of hopscotch. The game reaches its final stage when the molecules reach the outside of the PU film, where they then evaporate and seep through the ePTFE membrane as a gas, leaving the inside of the garment dry.

Liquid Coatings

Liquid coatings are solutions applied to the interior of a garment to provide WP/BR laminate-like properties. Generally speaking, liquid-coated WP/BR fabrics aren’t as dynamic and don’t perform quite as well as laminate membranes, but usually come in at a much lower price. As such, they are most commonly found in entry or mid-level rain shells or those intended for less extreme activities.

Some examples of brands that use coatings instead of (or as well as) laminates are Marmot, Rab, and Mountain Equipment.

Father and Son Hiking in the Rain

Liquid polyurethane coatings can take one of two forms: microporous coatings and monolithic coatings.

Microporous Coatings

These work much like the laminate membranes mentioned above — by using a microscopic network of channels that are too small for exterior water to penetrate, but large enough to allow vapor from sweat to escape.

The porous quality to these coatings is made in one of two ways: either with a foaming agent that forms gas bubbles that expand inside the coating, or with microscopic particles that are mixed into the coating solution in order to allow the formation of minuscule cracks and openings. During the process of drying and solidification, both methods create a network of tiny conduits in the coating through which water vapor molecules can escape.

Monolithic Coating

This form of coating works by creating a solid, hydrophilic (water-attracting) layer that conveys moisture by a trio of processes known as adsorption, diffusion, and desorption.

In brief, these processes work as follows:

Adsorption: The monolithic coating draws water molecules to itself owing to its hydrophilic properties

Diffusion: The liquid seeps through the coating owing to differential pressure. High pressure seeks low pressure and vice-versa, so the high pressure inside the jacket naturally gravitates outward to meet the lower pressure on the jacket’s surface.

Desorption: The vapor molecules evaporate and escape through the outer layer as a gas, completing the process of "water vapor transfer" that is measured in the WVTR, or "Water Vapor Transfer Rate," now found in the product descriptions of some WP/BR products.

The video from GoOutdoors above provides an insightful, and quirky overview of WP/BR fabrics and how they work.

Check out our hiking clothing buyer’s guides:

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What to Wear Hiking: The Foolproof Guide

WHAT TO WEAR HIKING: THE FOOLPROOF GUIDE

WHAT TO WEAR HIKING: THE FOOLPROOF GUIDE

Article Summary

QUICK TIPS: DO'S & DON'TS

One of the great many blessings hiking offers its followers is the absence of those bothersome formalities most of us are forced to adhere to in our workaday lives. When out in the wild, for example, such hassles as deadlines, meetings, dress codes, bosses, and paperwork are thankfully in short supply.

Sadly, however, this liberation from societal and professional strictures doesn’t mean taking a willy-nilly, devil-may-care approach is always the best way to go — particularly when it comes to hiking wear. In the outdoors, the “boss” is no longer that miniature dictator in the office at the end of the hallway, but the somewhat mightier proposition that is Mother Nature.

But just what does the grand matriarch of our planet demand of our attire when we head to pay her a visit?

In this article, we’re going to take you through the A-to-Z of suitable and practical apparel for your future appointments in the Great Dame’s domains, starting off with a look at a few simple pre-hike and pre-purchase strategies before delving into the finer details of material types and clothing choices per body part.

Looking to Learn to What to Wear on Your Next Hiking Trip?

You're in the right place! In this guide we will be covering the following:

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    A quick cheat sheet
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    How to dress for hiking stratigies
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    Pros & Cons of various Fabrics
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    Fabric Properties to Look for
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    What are the best clothes for hiking in various weather conditions

Do

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    Do read up on and familiarize yourself with the ins and outs of the layering system
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    Do your research before buying your threads. User reviews are a great way to learn how any product performs out in the field and usually offer a few insights not included in the specs and boasts of the marketing departments
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    Do buy the best gear you can afford
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    Do anticipate weather conditions and dress and pack accordingly, making sure to allow a buffer for any unexpected changes
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    Do make sure every item in your getup is breathable — if just one garment fails in this respect, it will bring down the rest of your layering system with it

Don't

  • Don't wear any cotton garments whatsoever. Cotton Kills!
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    Don't scrimp on the biggies. While a $120 fleece and a $20 fleece may not have too much difference between them barring a fancy logo, with other items — baselayers, waterproofs, footwear — a few extra $ could mean the difference between a happy hike and a hellish one
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    Don't give one single hoot about fashion — it’s very hard to look cool when you’re shivering with hypothermia, vomiting from sunstroke, or squeezing rainwater from your very trendy but otherwise inappropriate threads

What to Wear When Hiking: Cheat Sheet

If you are simply looking for a quick rundown or reminder of what to wear for hiking, then we have put together a quick cheat sheet below. Please take the following recommendations as a general hiking clothing guide based on our experience and personal preferences. 

The four scenarios below are fairly generic, which in addition to the infinite number of potential weather/trail conditions and combinations of appropriate apparel, we highly recommend reading through to the end of this article and doing some research of different products yourself to ensure you develop a clothing system that works for both you and your environment

What to wear hiking cheat sheet

Clothing Strategies for all Conditions

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A little bit of know-how with regard to pre-hike prep is the first step to becoming a true all-weather hiking warrior. Below, we’ve compiled a list of the fundamental need-to-knows that will guide you around the various pitfalls in store for relative novices to hiking and let you hit the trails with confidence in your backcountry couture.

Layer up

If there were ten holy commandments for hikers, using the layering system would surely be in the top three. This system, described in more detail in our definitive guide to how to layer clothing, is now all but universally accepted as the benchmark for backcountry habiliment.

backpacker wearing 3 layered clothing system

The layering system works by utilizing, as the name suggests, multiple strata of clothing items instead of only one or two bulkier items, thus creating air pockets between each layer and allowing interior moisture (sweat) to evaporate as it passes outward through the layers. It also offers a great deal of versatility in changeable weather by allowing you to take gear off and put it on with the minimum of fuss as temperatures rise and fall throughout the day.

Anticipate Weather and Trail Conditions

Before preparing your pack and getting dressed, study weather forecasts and allow a buffer for temperature variations and any forecaster whoopsies, particularly if your hike is taking you far afield.

Pro Tip: Elevation Gains & Temperature

An old-school, surprisingly reliable rule of thumb is that temps can drop roughly 3.5°F per 1,000 ft climbed (6.4°C/km). Using this simple calculation will allow you to estimate trail temps where forecasts are given for valley but not mountain locations.

Other factors to take into consideration pre-hike include conditions underfoot, humidity, the presence of bugs, trail aspect (in sun or shade), and the duration of your hike. These variables may require you to take along, respectively: gaiters or boots instead of shoes; quick-drying garments; facial bug nets; warmer individual layers; and, extra items (particularly if on a multi-day excursion). 

Embrace Your Fugly

Mountain-goers are not renowned for their style, and for good reason. Out in the wild, factors such as comfort, weight, functionality, durability, performance, and price trump fashion every time. While the odd backcountry fashionista is occasionally to be found, the chances are they’ve paid a pretty penny for their fancy togs and will almost certainly be that one, ever-present group-member imploring you to part with your spare sweater when the weather takes a turn for the worse.

hiker in the mountains, Iceland

Treat Your Feet

Whatever your budget, be sure to pick a pair of boots or shoes that are fit to task. Ill-fitting or poorly made boots or trail shoes can not only be a source of great pain or discomfort, but can also lead to injury by causing you to walk with an unnatural gait or skipping on important features such as ankle support, grippy soles, adequate cushioning, waterproofing, protective toe rand and/or ample bridge support.

Pro Tip: Take the Load Off

If you plan to fit in some overnight stops on your next trip, then consider taking a pair of lightweight, breathable camp shoes with you. There is a multitude of reasons why investing in pair is a great idea.

There are many opinions on whether boots that cover your ankles are a must versus wearing a pair of lightweight hiking shoes, or even hiking sandals. In the end it comes down to the type of terrain you'll be covering, your own walking style (injuries) and preference.

To avoid going through a long (and costly) process of trial and error before finding the boots or shoes that work for you, be sure to research the options thoroughly, read user reviews, and spend plenty of time trying out your would-be new footwear in the store before heading to the checkout.

Cheap Hiking Boots Title

While many top-of-the-range, technical hiking or mountaineering boots will set you back enough $ to sponsor a small war, there are plenty of more wallet-friendly options out there for those who have no intention of scaling the Eiger’s north face or traversing the Himalaya in winter. Check out our guide to the  best cheap hiking boots to see our top affordable picks.

Bright colors

A bit of a wild-card entry here. Some old-schoolers are apt to lament the visual impact of hikers who look like technicolored candy wrappers out on the trail, but the benefits of wearing slightly garish garb far outweigh the traditionalists’ interests in defending their delicate sensibilities. If injured, lost, or otherwise in need of assistance, colorful threads will make you far more easily discoverable than more natural tones.

Know Your Fabric Choices

The success or failure of your future hiking trips depends largely on the choices you make when purchasing your gear. These days the number of options at our disposal is mind-bogglingly high. So much so, in fact, that novice hikers could be forgiven for grabbing the first decent-looking garments they lay their hands on to spare themselves the cognitive overload. To help you avoid this temptation, below we’ve listed the most popular hiking fabrics along with their benefits and drawbacks.

Fleece

Fleece is a great, low-cost insulator that dries quickly and offers an excellent warmth-to-weight ratio. Ideal as a midlayer, soft against the skin, and quick drying, the only drawback to fleece is a lack of wind-resistance when worn without a protective outer shell.

Senior Man On Hike Through Beautiful Countryside in fleece jacket

Polyester/nylon

These synthetic fabric types feature in everything from shoes and gaiters to baselayers, shirts, jackets, and hats. They come in many forms and with varying specs, and most big brands offer their own trademarked variation such as Air Tech (Mountain Hardwear), Capilene (Patagonia), and Polartec (various).

Although polyester/nylon baselayers, shirts, and midlayers aren’t always as comfortable or stink-free as, for example, merino wool or bamboo products, they are usually a cheaper option and dry much quicker.

Most outer, shell layers also use polyester or nylon (or both) with a DWR (Durable Water Repellent) finish to provide protection from the elements.    

Wool

Wool has undergone something of a revival in recent years, mainly thanks to brands such as Icebreaker and Smartwool. Modern wool-made hiking garments are far more high-performing than those of yore and offer a slightly pricey but otherwise cozy, soft, stink-free, breathable, and high-wicking option that insulates even when wet and works particularly well in baselayers, as explained in the video below.

The only downside to wool is that it offers little wind resistance, is often pricey, and, particularly in meatier layers, can take a long time to dry.

Down

The perfect insulator in dry, cold conditions. Down garments use different ‘fill powers’ (usually between 400 and 900) which refer to the amount of insulation offered by the garment’s feathered contents. In short, the higher the fill power, the more body heat a down product can trap.

If heading into high alpine environments, down is a great choice, but in more humid conditions synthetic fabrics are a better option — when wet, down loses most of its insulating ability and can take a small age to dry out.

Well built young man relaxing drinking hot drink and holding metal vacuum flask

Silk

Silk, really? Yeah, really. Though fairly rare these days, silk was once the fabric of choice for the world’s mountaineering elite, mainly due to its ability to provide superb insulation at an incredibly low weight. On the downside, it costs a small fortune, wicks about as well as your average sponge (i.e. terribly), and tears very easily.

Cotton

Cotton is the junk food of the world of outdoor attire. It’s cheap, easy to get your hands on, looks and feels good for a while, but ultimately contains the capacity to be downright deadly.

Famous for soaking up sweat, failing to wick, and lacking in breathability, cotton is not only liable to cause fairly minor discomforts such as soggy undergarments and chafing, but can also lead to hypothermia and, in extreme cases, death — as explained in more detail in our article Why Cotton Kills. To be avoided at all costs.

Hiking Fabric Properties & Qualities 101

Whatever fabric type you end up choosing for any garment, the label or product description will most likely boast one or more desirable properties or functions. But just what are these properties and when or where do we need them?

Wicking

The term “wicking” essentially refers to a fabric’s ability to transport moisture (i.e. sweat) from inside to out, thus moving it from your skin or internal layers to the outer surface. This property is important for two reasons: one, so you don’t feel like the resident of an otter’s pocket while working up a sweat; two, you greatly reduce your risk of hypothermia, the chills, death, and other such nasties when your sweat cools down — a real possibility with fabrics that don’t wick so well.

Pro Tip: Research Marketers Claims

Nearly all baselayers and t-shirts will claim to be “high-wicking” (“low” and “middlingly” just don’t feature in the advertisers’ vocab), so before buying be sure to read a few user reviews or to pick the brains of a knowledgeable shop assistant.

Insulating

In order to stay warm, you need to create a buffer between yourself and the ambient air and elements. A good insulating layer may take many forms — wool, fleece, down, polyester down substitute — but all of these do one thing well, namely keep in the heat produced by your body.

Generally speaking, the thicker the layer, the more insulation it will provide, but be wary of sacrificing breathability if opting for especially heavy midlayers, particularly those using synthetic materials inside a wind or water-resistant shell.

Waterproof

Shell layers may boast a number of desirable facets, features, and extra frills, but the undoubted “must-have” of these is their ability to keep out the elements. The most important thing to note when buying an outer shell — whether pants or jacket — is that nearly all garments will fall into either the “water-resistant” or “waterproof” category. What is the difference between waterproof and water resistant? The distinction is an important one. While the latter are made to keep you totally dry, the former are designed to shed only moderate precipitation, such as light drizzle or a short-lived shower.

A second point of note is that any garment that is entirely waterproof will also be windproof — handy given that wind can be as effective as cold ambient air and saturated clothes at spiriting away your body heat.

Finally, thanks to Hydrostatic Head testing (a.k.a. ‘Pressure Head’ testing), there are now degrees of waterproofing. Given in a measurement of mm, these ratings refer to the amount of liquid a garment’s material can withstand before allowing droplets to seep through. At the lower end of the scale, a jacket with a 1,500 mm rating will keep you dry if caught in a spot of drizzle, while one boasting a 20,000 mm rating with do the job even when things take a turn for the biblical and your neighbors start building arks.

For a more detailed guide to waterproof hiking duds, check out our guide Hiking in the Rain.

Breathable

Perhaps the most important item on our list, “breathability” refers to a garment’s ability to transfer moisture from inside to the outside, rather than trapping it within any given layer. This is particularly important in the performance of your base layer, as it allows the moisture wicked through to the outside of the baselayer fabric to dry more quickly and takes the moisture away from your skin.

Hikes on top of a mountain

That said, if any garment in your layering system doesn’t breathe well, the rest of them are unable to fulfil their function. This can result in an accumulation of moisture trapped inside your layers and, at worst, the perfect environment for a significant loss of body heat, and potentially hypothermia, when you stop moving or temperatures drop.

Waterproof and breathable

A completely waterproof and breathable outer shell has long been considered the Holy Grail of outdoor attire, and these days the R&D departments of the biggest brands have just about delivered the goods. There is, however, a catch: the price. Yep, you can get your hands on a jacket or the "best rain pants" on the market that will fend off small tempests and monsoonal deluges, all while letting your body and inner layers breathe, but only in exchange for a tear-inducing portion of your savings.

More affordable options usually feature a compromise on either of these two above features, with the most breathable fabrics being less waterproof and the most waterproofed being less breathable. 

At the economy end of the scale, there are coated non-breathable shells, which may look like they will do the job but a short way down the trail are likely to make you feel like you’re wearing a spacesuit in a steam room due to their lack of breathability. A happy medium, however, can be found in many mid-range Gore-Tex jackets such as the Marmot Minimalist, which breathes well, boasts a healthy 28,000mm waterproof rating, and also won’t break the bank.

Windproof

As mentioned above, hardshell waterproofs will also tick the windproofing box and can be worn on top of even the lightest baselayers to ward off the windchill. If conditions are dry but cool enough to demand some degree of insulation, midlayer tops such as the Rab Focus Hoody feature a tight enough weave to resist the worst of the wind’s efforts while providing more insulation than thinner outer shells.  

Stretch and Mobility

When out hiking, mobility is a big deal. Not only should clothing be sufficiently loose fitting to ensure you can move freely, avoid chafing, and allow for some air-flow between layers, but can be made all the more comfortable if it contains an element of stretch and/or added material in key areas.

mature backpacker on a mountain ridge in hiking tights

Features like a stretch waistband, gusseted crotch, softshell inserts on hardshells, or fabric containing some percentage of lycra, elastane, or similarly stretchy materials can greatly enhance comfort levels and allow you to move without restriction.  

Sun protection

Unless you happen to be a night-hiking enthusiast, choosing a fabric that boasts an ultraviolet protection factor (UPF) rating is never a bad idea. The perils of skin cancer need no introduction here, but the added risks to hikers of this and other sun-induced illnesses are well worth noting. Hiking at altitude, on snow, and/or spending far more hours exposed to the sun’s UV rays all make hikers a particularly at-risk demographic in need of extra protection from the big yella fella.  

group of hikers

In a nutshell, UVF ratings run from 15 to 50+, with the higher numbers offering superior protection (a UPF rating of 20 indicates the fabric of a garment will allow 1/20th of available UV radiation to pass through it, a rating of 50 will allow 1/50th, and so on).

From Top to Toe - Hiking Clothing Choices

The following overview is designed to provide a nuts-and-bolts guide for all-season hiking, working on the premise that you only need to add or subtract layers according to the temperatures you are hiking in.

Tops

Whatever the weather conditions, the fundamentals of the layering system up top remain applicable. We recommend starting with a breathable, high-wicking baselayer, varying the weight or thickness depending on temperatures. If you’re out in very cool conditions, this can be supplemented with a thicker fleece or down midlayer before being topped off by that all-important shell or water and windproof layer.

hiker tourist travels to green mountain forest in the fog with the red backpack in rainy weather

In warmer weather conditions where the outer shell is not necessary but you need more than a t-shirt, an outer layer with some wind resistance will serve you better than anything made of fleece or wool, both of which tend to have sieve-like qualities in anything more than a light breeze.

Bottoms

In very hot temperatures, you can either opt for a pair of lightweight trousers such as The North Face Paramount Trail Pants, or a pair of shorts or skorts — just be sure to check you won’t be wading through thorny or nettle-riddled brush before plumping for the latter. The ideal solution is to get your hands on a pair of light hiking pants with zip-off bottoms and ankle zips that allow you to remove the lower sections without taking off your boots.

Pro Tip: Remember to Buy a Bit Baggy

When buying outer shell layers, be sure to leave room for the layers you’ll have underneath.  

In colder temps, a good idea is to start with a pair of softshell pants with some degree of wind resistance or to wear a baselayer pant or hiking tights below your standard trekking pants. If conditions are wet or particularly blustery, throwing a pair of lightweight waterproof rain pants directly on top of either your baselayer or standard hiking pants will keep your pins toasty and dry.

Footwear

Your choice of footwear will depend largely on where you plan on doing your hiking and the conditions you’re likely to find there.

It goes without saying that in muddy, boggy, or snow-covered terrain a pair of backpacking boots will serve your purposes better. If you foresee doing most of your hiking on well-maintained trails and aren’t a fan of wet-weather wandering, however, a pair of waterproof hiking shoes could save a bundle of cash and offer a much more nimble, and often more comfortable, alternative. To help you choose, check out our guide to The Best Hiking Footwear of 2018.

Extras

  • Sunhat — Spending hours on the trail under even a moderate sun can make you vulnerable to heatstroke, sunstroke and, of course, burning. As such, choose the best hiking hat you can find - this 50-100g addition is well worth its inclusion in any backpack on sunny days.
  • Sunglasses — An optional extra that becomes all but imperative when in snow-covered terrain, where snowblindness and headaches become a real possibility for unprotected lookers. For glasses that give your eyes complete protection, we’d recommend a pair featuring protective side shields, such as the Julbo Vermont, which also happen to look, quite frankly, awesome.
  • Gloves — Conditions will dictate just how serious a pair of gloves you need, but a general rule is that if it’s cold enough to have one pair, it’s cold enough to have two. A second liner glove can serve as an emergency backup and prove very useful for limiting exposure when performing more delicate tasks such as taking pictures, tying laces, putting up your tent, or taking readings from a map and compass.
  • Gaiters — A very handy addition to help keep your feet dry when hiking in boggy, wet terrain, and also for keeping small stones, twigs, snow, and bugs out of your boots.
  • Buffs — This very lightweight, versatile little piece of gear is a worthy addition to any hiker’s kit. It can be used as a hat, neck warmer, and a substitute bandana to provide sun protection
  • The best socks for hiking? — Again, avoiding cotton is essential. Breathable wool socks such as Darn Tough’s Micro Crew Hiker Cushion Socks or tech variants like Wrightsock’s Escape Crew are the best way to avoid soggy soles, blisters, and, of course, stinky feet. Check out our guide for a more thorough analysis and buying choices.
  • Underwear — As with other garments, steer clear of cotton. Perhaps more than any other body part, your intimates need to breathe and shed excess moisture. Merino wool and quick-drying “tech” undies such as ExOfficio’s Give-N-Go Sports Mesh Boxer Briefs are high-wicking and far more breathable than standard cotton items. For females, the Under Armour Heat Gear Sports Bra is a winner.

How Can We Help You Improve Your Outdoors Wardrobe?

What duds you choose to wear in the outdoors can make the difference between a happy, wonderful experience to one of abject misery or even worse, a dangerous one. Always remember the Scandinavian saying "Der findes ikke dårligt vejr, kun forkert påklædning" which translates to "There is no such thing as bad weather, just bad clothing". If you learn to dress correctly, you'll be able to tame any outdoors adventure, no matter what mother nature throws at you.

There are multiple myths and misunderstandings around what is good (or not) to wear. As such, our in-house experts cover a range of clothing related subjects to bring you actionable advice to help you improve your skills and knowledge, to make all your future trips that much more enjoyable. Happy Trails!

Woman hiking in winter cold dark winter forest

CLOTHING GUIDES

Possibly the most critical gear to determine the success (and safety) of a trip is the choice of clothes on your back.

hiker in the mountains, Iceland

CLOTHING GEAR

Not sure which jacket to buy? or what makes for a good pair of hiking socks? Don't fret! We test & review so you don't have to.

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Waterproof vs Water Resistant: What’s the Difference?

WATERPROOF VS WATER RESISTANT: WHAT'S THE DIFFERENCE?

WATERPROOF VS WATER RESISTANT: WHAT'S THE DIFFERENCE?

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When the backcountry boffins first started differentiating between water resistant and waterproof a few decades ago, many of us suspected a trick, or at least an over-fussy and finicky distinction that could, for most of us, be politely ignored.

Well built young man relaxing drinking hot drink and holding metal vacuum flask

In the interim, the boffins have been exonerated, and their fussiness revealed as symptomatic of the huge strides that have been taken in outerwear technologies in recent years. We slowly, and some of us with tails between legs (this writer included), realized that the distinction made was not only a valid one for scientific reasons, but also one that was pivotal to getting our hands on the correct clothes to wear hiking

Read Our Clothing Buyers Guides:

  • Looking for the best hiking leggings? Look no further!
  • Picking the best hiking socks for warm weather can really improve your trip experience
  • Don’t get caught out in the sun without the best backpacking hat!

To help you do the same, this article will bring you a short-and-sweet guide to the difference between water-resistant and waterproof garments.

Water Resistant Clothing

Water-resistant fabrics do precisely as their name suggests, that is, resist water to lesser or greater degrees. Compared to waterproof varieties of garment, these products are less capable of preventing saturation from rainwater.

Senior Man On Hike Through Beautiful Countryside in fleece jacket

Unlike waterproof jackets, the ability of water-resistant varieties to repel moisture relies entirely on a durable waterproof repellent (DWR) coating that is applied to the outer fabric during production. This coating prevents water absorption by a process described in more detail in our guide to DWR waterproof coatings. In a few words, this coating (sometimes also referred to as a “lining”) causes water to bead up on the garment’s surface and run off before saturating the fabric.

  • Suitable for light rain showers
  • Generally less expensive
  • Don’t have taped seams
  • Treated with a DWR finish but don’t have a waterproof membrane

Ratings

DWR ratings are determined by the percentage of fabric with no water sticking to it following a simple spray test. For example, if the DWR rating is 80, then 80% of the fabric was water-free after the spray test. A second figure indicates the garment’s performance in the same spray test after a number of washes. For example, a rating of 90/20 tells us that the fabric maintains a 90-point rating (being 90% water-free in the spray test) after 20 washes.

  • 80 points/10 washes — The bare minimum for classification as DWR in most outerwear
  • 80 points/20 washes — The typical DWR rating for most water-resistant garments
  •  80 points/50+ — Exceptional water repellency, usually used in either very high-end waterproof products or garments which lack a waterproof membrane and rely only on DWR for water resistance

As you may have guessed, after so many washes you will have to reapply a DWR coating with a DWR detergent such as Nikwax.

Waterproof Clothing

Waterproof garments usually combine a DWR coating on the outer fabric, fully taped seams, and a built-in membrane lining such as those described in our article on waterproof and breathable fabric (Gore-Tex, eVent, HyVent are a few of the most popular varieties).

backpacker wearing 3 layered clothing system

A membrane lining is an incredibly thin film or sheet of material with literally billions of microscopic holes which are too small for rainwater to penetrate but large enough for water vapor molecules (from sweat) to pass through in an outward direction. This membrane assists breathability and forms a second, more impermeable barrier after the DWR outer.

  • Suitable for heavier rain
  • Use a waterproof fabric membrane (such as Gore-Tex, eVent, or HyVent)
  • Outer layer treated with DWR (Durable Water Repellent) finish
  • Taped seams
  • Generally more expensive

Ratings

The waterproof capacity of any garment is quantified by hydrostatic head ratings, which are covered in more depth in our guide What is Hydrostatic Head? The legal minimum hydrostatic head rating for classification as a waterproof garment is 1,500mm, which we’ll take as a starting point for the summary below.

  • 1,500mm — 5,000mm = Can deal with only very light rain and, at that, not for sustained periods. Most commonly found in jackets intended for “casual”, everyday use than in performance models.
  • 10,000mm = Suitable for light rain showers but liable to leak at pressure points where the straps of your backpack are in contact with the jacket (the shoulders, back, and belt area). Jackets with this rating often focus more on breathability than on waterproofing, as exemplified by Polartec Neoshell.
  • 20,000mm = Capable of dealing with heavy rain showers and seen by some manufacturers as the max waterproofing capacity required.
  • 30,000mm = Garments with this rating provide solid waterproofing in even the heaviest downpours, but occasionally at a cost to breathability. This HH rating is used in jackets and rain pants for hiking in extreme conditions, such as eVent’s DV Expedition models.

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How to Care for DWR cover

How to Care for DWR

HOW TO CARE FOR DWR PRODUCTS

how to care for dwr products

Even if you've done your research, and have bought the best rain pants for hiking, or that expensive Gore-Tex jacket you'll still need a little bit of TLC to keep your outdoor gear in top shape for the long run. This is never more true than in the case of products with a DWR finish, which of all items in out backcountry kit are liable to deterioration with time and frequent use but can be restored to factory-like efficiency with just a minimal outlay of attention and effort.

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In this article, we’ll show you how it’s done with a short, practical guide on to how to get the most out of your DWR product.

Potential Performance Issues with DWR Products

The water resistance in DWR products can deteriorate and lose effectiveness with time owing to repeated washing, abrasion, weather exposure, and contamination by things like dirt, grease, and sweat.

To check if the effectiveness of your DWR product has declined, simply spray or pour a few drops of water on its surface at various points. If the water beads up and rolls off, or drops off after a gentle shake, then your DWR coating is healthy and not in need of reactivation or restoration. If, however, the water spreads on the surface and darkens the material, then it’s treatment time…

Maintenance & Care Measures for DWR

A number of measures can be taken to reduce the deterioration of a DWR coating and perk up its water-repellent properties:

Senior Man On Hike Through Beautiful Countryside in fleece jacket

Regular Washing

Many hikers are apt to think that washing a breathable waterproof fabric product a will somehow damage it. In reality, regular washing of your waterproof jacket is the single most important factor in keeping the garment healthy and maintaining DWR performance.

To wash your DWR product, follow these instructions:

  1. Wash the garment with an additive-free detergent like Nikwax Tech Wash (not liquid detergents or anything that contains fabric softeners as these can impact the effectiveness of the DWR finish). 
  2. Before washing, read the care label inside the jacket and follow any specific instructions provided.
  3. Machine wash your garments on a full cycle.
  4. Repeat the rinse cycle to make sure all soapy residue is removed.
  5. Machine dry on a low/medium setting or leave to dry on a radiator.

How to Re-Waterproof a Jacket

While the above measures (tumble drying and washing) are preventative in nature and can be used to slow down the deterioration of a DWR coating’s effectiveness, after a number of washes you may notice that washing alone is not enough to revive the water repellency of your jacket. If this is the case, you most likely need to take the more pro-active measure of re-proofing your garment.

Well built young man relaxing drinking hot drink and holding metal vacuum flask

Reproofing is a simple process that restores the durable water repellency in your jacket as closely as possible to its factory levels of waterproofing and is fundamental to the longevity of your jacket’s effectiveness. How often you need to re-proof your jacket will depend on how regularly you use it and how often you wash it. A ballpark figure that can be applied to most products is to reproof every 15-20 washes.

Wash-in Reproofing

To reproof your jacket with a wash-in treatment, use the following instructions:

  1. Preparation - First up, wash your jacket using the instructions given above. Once dry, double-check that you have the right treatment for reproofing your jacket: for DWR finishes, products like Nikwax Softshell Proof, Nikwax TX Direct Wash-In, or Gear Aid ReviveX will all do the trick.
  2. Wash - Machine wash your garment as advised on the label’s care instructions.
  3. Dry - Tumble dry your jacket on a low setting or hang to dry on a radiator.
DWR reproofing

Spray-On Reproofing

Reproofing your DWR garment with a spray-on treatment is a more “time-efficient” option that produces similar results to using a wash-in product. To do so, wash your garment as instructed above, leave to dry, and then cover it thoroughly with the spray, taking care not to miss any portion of the material (as seen in the video above).

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why cotton kills featured image

Why Cotton Kills: Discovering the Dark Side to this Fluffy Fabric

WHY COTTON KILLS: DISCOVERING THE DARK SIDE TO THIS FLUFFY FABRIC

WHY COTTON KILLS: DISCOVERING THE DARK SIDE TO THIS FLUFFY FABRIC

Article Summary

QUICK TIPS: DO'S & DON'TS

Certain things just weren’t made to go together. We’re thinking hydrogen and naked flames, orange juice and toothpaste, humans and mullets, socks and sandals. Very worthy additions to that list, for the non-masochistic hiker, are water and cotton. Alone, the two are perfectly harmless and, of course, quite useful; combined, their potential consequences for the active outdoorsperson are at best unfavorable, at worst downright deadly.

So what is it about cotton that makes it such a reliable midwife to mishap, calamity, and catastrophe, and the subject of such ubiquitous scorn among knowledgeable outdoor folks? And what are the best clothes for hiking for those who’d prefer to return home minus a dose of the chills, hypothermia, or in spirit only? 

This article aims to answer both of these questions, dipping into a modicum of science, constructive cotton-bashing, and then providing the skinny on more appropriate outdoor attire.

Looking to Learn to More About the Dangers of Cotton?

You're in the right place! In this guide we will be covering the following:

  • check
    A breakdown of why cotton is so dangerous in the backcountry
  • check
    Which material provides warmth even when wet?
  • check
    An introduction to the outdoors clothing layering system

Do

  • check
    Plump for high-wicking synthetic fabrics over cotton
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    Research the insulation, wicking, and breathability capacities of all items of clothing before buying
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    Use a layering system appropriate to weather conditions and your activity
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    Make every effort to stay dry — shed layers when overheating and open zips, cuffs, and drawcords to ventilate when hiking in the rain

Don't

  • Wear cotton on the trail. Period!
  • exclamation-circle
    Think that moderate weather conditions mean moderate risk — hypothermia can strike when temps are well above zero
  • exclamation-circle
    Be put off by the high price-tag of some synthetic or woolen hiking threads — the initial outlay is well worth it

Why Cotton Kills

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In recent years, the pages of outdoor monthlies and their online newsfeeds have been no strangers to tragic stories of hikers who have died or been hospitalized as a result of wearing inadequate clothing in the mountains and backcountry. In many of these cases, the casualties shared one common denominator: the use of cotton.

Woman hiking in winter cold dark winter forest

It feels soft, is comfortable, and looks better than shiny synthetic duds when we’re going about our regular, day-to-day business, but put to the test of just a short stint of athletic exercise, cotton quickly reveals itself to have tendencies bordering on — and occasionally tantamount to — the homicidal.

Clothing Related Topics

Check out our waterproof/resistant mini-guides to find out:

Water and Cotton

The terms ‘wicking’ and ‘breathability’ are ever-presents in any discussion of outdoor clothing. Wicking is the process by which perspiration filters or seeps (i.e. wicks) through the material of any given fabric from the inside to the outside, thus leaving that material and our skin dry. Breathability refers to any fabric’s ability to allow moisture vapor to be transmitted through the material instead of trapping it inside.

In terms of breathability and wicking capability, cotton is a very shoddy performer. Instead of transporting the moisture from your body to the outside, it simply collects it, much like a sponge. Cotton garments, in fact, can absorb up to a whopping 27 times their weight in water.

Unlike other fabrics, cotton is so absorbent because its fibers are essentially tiny tubes (called ‘lumens’) which can act as thousands upon thousands of minuscule containers for moisture, thereby leaving us clad in sodden fabric whenever we’re working up a sweat.

Pro Tip: Be Prepared for Emergencies

In addition to dodging cotton, we’d highly recommend carrying an emergency blanket, even in summer

If the air temperature happens to be significantly lower than our body temperature, all that water trapped in a cotton garment’s fibers will soon leave us feeling chilled because the garment is not only failing to provide any insulation, but also actively decreasing our core temperature at the same time.

Why Being Wet is a Problem

Water can conduct heat away from the body up to 25 times faster than air. As such, staying dry in the outdoors is all but a prerequisite to staying warm.

group of hikers

Cotton garments flaunt this requirement on two grounds. First, by their absorption of moisture. Secondly, their subsequent loss of insulating properties. When dry, cotton garments provide insulation by trapping air between themselves and the skin; when wet, this buffer disappears and increases our exposure to radiant heat loss.  

Being wet in and of itself is not exactly one of the hiking world’s cardinal sins — there are a few of us, for example, who will gladly douse our shirts in water while out on a hike in crazily high temps, or who have left our waterproof rain pants at home, and taken a good soaking in a rain shower, yet lived to tell the tale. Many desert hikers even extol the virtues of cotton for its capacity to keep them cool when the mercury’s through the proverbial ceiling.

The problem starts when that wetness is allowed to cool down excessively owing to any of a number of factors: injury, rest stops, altitude gain, nightfall, getting lost, a change in weather conditions, descending instead of ascending, moving at a slower pace.

For hikers, the process frequently goes something like this: we start off on our hike, gradually building up a sweat as our graft gets underway; that sweat begins to douse our apparel but remains warm due to our continuing exertions and body heat; then the trail turns downhill, the sun drops, the wind gets up, or we pause to take a photo/pee/look at our map etc.; suddenly that warmth is a distant memory, we are chilled to the bone, and our core temperature is headed dangerously south.

mature backpacker on a mountain ridge in hiking tights

The above is fairly textbook example of the onset of one of the outdoor world’s most common and life-threatening ailments: hypothermia.  

Hypothermia

Over 1,500 people die from hypothermia each year in the US alone.

Hypothermia occurs when our bodies lose heat faster than they can produce it, and when our core body temperature drops below 95F. The early symptoms of hypothermia include disorientation, shivering, a weak pulse, confusion, drowsiness, memory loss, and lethargy. The latter are a loss of consciousness and, if our core temperature drops too low, heart failure.

Being exposed to variations in weather conditions and fluctuating temperatures, straying far from shelter, and perspiring heavily all combine to make hikers a demographic that is at particular risk of contracting hypothermia.

While maintaining a healthy core temperature might seem like an easy task in the year’s more clement seasons, this is in fact exactly when the vast majority of hypothermia cases are recorded. Relatively few occur in the winter, principally because at this time of year we tend to take extra care to ensure we’re suitably dressed and equipped.

Man hiker looking over fjord panorama

In summer, spring, and fall, we’re far more likely to be more casual in terms of clothing choices and underestimate weather conditions. In fact, the most important take-home of this article — beyond the inadequacies of cotton — should be that hypothermia can strike at almost any time, even in temperatures well above zero.

Preparedness

April 29, 2018, saw the most deadly day in the European Alps since World War One’s infamous White Friday, with 14 mountaineers and ski-tourers perishing in 5 separate incidents. Though a debate still rages on regarding where to place blame for the incidents, the general consensus is that an underestimation of weather conditions and ill-preparedness were keys factor in at least 7 of the deaths.

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Following a week of high temperatures, a freak blizzard caught each of the parties unawares, underequipped, and unsuitably attired. Without wishing to do a disservice to the deceased, it is a story we have heard all too often before, and one that echoes — in nature if not degree — countless other hiking tragedies across the globe.

Being caught unawares is an eventuality all of us can avoid. The first step we should take in order to ensure our wellbeing in the outdoors is adequate preparation, and the first box to tick in this respect is ensuring we wear appropriate clothing. A condensed working definition of ‘appropriate’ reads something like the following: “high-wicking, breathable, insulating, and devoid of any trace of cotton.”

Winter hike

Thermal Value

Following the deaths of several hikers in the early 1960s, a series of experiments conducted by the Royal College of Surgeons (which included Dr. Lewis Griffith Cresswell Evans Pugh, the physiologist who had been crucial to the successful summit of Everest in 1953) discovered that the “thermal stress” responsible for each of the deaths was a result of inadequate clothing.

Although the victims had been wearing an ample amount of clothing, their demise was expedited by its form: jeans (denim is a form of cotton), cotton t-shirts, cotton underwear, and sweaters made of a wool-cotton blend. The subsequent experiments found cotton garments to have a thermal value of next to zero when exposed to wet and windy conditions.

How Other Fabrics Keep You Warm

So, what do other fabrics do that cotton does not? The short answer goes something along the lines of the following: “wick”. A more detailed answer for different fabrics is given below.

Wool

Let’s start with the drawbacks. Wool is, generally speaking, a pricier option that can take a long time to dry out when wet. It also doesn’t wick quite as well as high-performing synthetic fabrics and can absorb up to 35% of its own weight in water.

The positives are that wool is a massive improvement on cotton. Not only does it continue to insulate when wet, it also offers a better warmth-to-weight ratio than most synthetic products, is highly breathable, and wicks reasonably well. Some wool-synthetic blends, such as those produced by Icebreaker, offer much better performance wicking-wise.

Thru Hiker making his way along trail

The fibers in any wool garment’s outer layer comprise a microscopic coating called an ‘epicuticle’. This layer acts as both a repellent to water and wicks vaporized liquid (i.e. sweat) away from the body, into the material, and then out again as a result of spreading the liquid over a larger surface area, thus facilitating evaporation. Additionally, wool fibers provide insulation even when wet thanks to millions of tiny air pockets that form in the gaps (technically, ‘crimps’) between each fiber.

Synthetics

Synthetic products made specifically for athletic exercise and the outdoors come in an array of forms and with varying specs. Their efficiency, however, is measured by one key feature that distinguishes them from everyday, non-technical garments. You guessed it…wicking capacity.

Some of the more notable, big-brand forms of high-wicking, breathable fabrics include Capilene, Dry-Line, Cool-Lite, Primaloft, Coolmax, Polarfleece, FlashDry, and Gore-Tex (outer layers and shoes/boots). If in doubt, the bottom line is that polyester-based products do not absorb moisture.

Each of the above outperform cotton products by a) transporting moisture from your body to the exterior of the fabric, where the process is then repeated by a subsequent layer (or, if you’re only wearing one layer, evaporating in the ambient air), b) providing some degree of insulation even when wet, c) drying quickly, d) retaining breathability.

Pro Tip: Not All Synthetics Are Great

Not all synthetic materials are the gold standard of wicking capabilities. In fact, some even outperform cotton in the ‘useless when wet’ and water-retention stakes.

Some of the more common fabrics to avoid include rayon, viscose, modal fiber, Tencel, and Lyocell, all of which are synthetic but comprise some degree of the same cellulose fiber responsible for cotton’s sponge-like absorption.

Although silk garments were de rigueur at the time of the early European expeditions to the Himalaya, their use was only effective at high altitude, where the climate is far drier than where most of us do our hiking. Though not as poor a performer as cotton, silk is another weakling wicking-wise and offers all but zero insulation when wet.

Layering System for Clothes

As covered in our more detailed analysis on How to Layer Clothes for Cold Weather, layering is essentially a means of effectively managing body temperature through the use of breathable strata of garments that wick perspiration away from your skin whilst retaining body heat between each layer.  

backpacker wearing 3 layered clothing system

The standard layering setup consists of a baselayer, midlayer, and outer layer. Each layer has its own function, with the baselayer fundamental to moisture management, the midlayer all about insulation, and the outer layer providing protection from the elements.

Pro Tip: Be Proactive

Don’t wait until you’re peeling ice from your skin before adding a layer — once your core temperature drops, getting it back up again can be a tricky business.

Cold hands and cold feet are usually not so much symptomatic of substandard socks, boots, or gloves, but of a dangerously low core temperature — if you start to feel the nip, don’t ponder a remedial gear purchase but throw on another layer instead.

In each layer, breathability and wicking are essential: should any single layer not do both adequately, the whole system breaks down. As such, any layering system that contains cotton is destined to fail.

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What is DWR_ cover

DWR: What is it & how does it keep you dry?

DWR: WHAT IS DURABLE WATER REPELLANT?

DWR: What is durable water repellant?

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These days, outdoor clothing manufacturers tend to litter their product descriptions with all kinds of kooky terminology and acronyms as though every would-be buyer had a Ph.D. in textile technologies and a team of Nobel Prize-winning scientists on speed dial. One such term is DWR, which in recent years has become something of an ever-present in the specs and selling points of everything from our shoes to the outer shells of rain jackets & hiking rain pants

Check out our other hiking clothing guides:

But just what is DWR coating? What does DWR mean? Is DWR waterproof vs water resistant? And, whatever it is, do we need it? 

In this article, we’ll answer the above questions and provide further insights into the workings and usefulness DWR, why you need it, how it’s gauged, and how to care for garments with a DWR finish.

NOTE: PhDs and teams of Nobel Prize winners not required for further reading.

What is DWR Finish?

The acronym DWR stands for Durable Water Repellent, and refers to a coating applied to a product during production to add water resistance. Usually used in conjunction with waterproof breathable membranes such as Gore-Tex or an eVent layer on the interior, a DWR finish is intended to prevent the exterior of any product becoming saturated and thus impeding the garment’s overall breathability and water resistance.  

A Very Short History of DWR

DWR finishes or coatings are not a new idea and find an early ancestor in the grease from animal fats and oils (such as linseed) used by early explorers, fishermen, and tribes such as the Inuits to coat tents, sails, and clothing.

Modern chemical-based DWRs were first used shortly after the introduction of GoreTex in 1969, when it was discovered that the waterproof lining in any three or two-layer garment would perform better if used in conjunction with an exterior coating that prevented the outer layer becoming saturated with water.   

How Do DWRs Work?

So what does water repellent mean and how does DWR protect you from the elements? DWR fabric work by allowing the material to which they are applied to shed liquid instead of soaking it up upon contact. To the naked eye, this effect is seen as water droplets beading up and rolling off the surface of the material.

At a more detailed, microscopic level, this process is far more complex and depends upon the angle of contact between moisture and the DWR textile. In layman’s terms, a DWR coating increases the contact angle between the fabric’s surface and moisture and the higher the angle of contact the better: low contact angles result in the droplet spreading out on the surface and soaking into the fabric, whereas with a higher angle of contact the water forms into a round bead or droplet and rolls off.

DWR Ratings

The DWR rating of any product is evaluated using a simple spray test. Water is sprayed onto the fabric and then the degree or level or water repellency is assessed visually by gauging the quantity of standing water remaining on the fabric’s surface. Ratings or scores are generated in points determined by the percentage of fabric with no water sticking to it. For example, a product with a 90 point rating means 90% of the fabric had no water sticking to it after spraying.

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In order to test durability, the same test is repeated after various numbers of washes, which is indicated in the second number given in any rating. For example, a rating of 80/20 shows that the fabric retained an 80-point rating after 20 washes, or it was 80% water-free in the spray test following 20 washes.

What DWR Rating do I Need?

Differing from hydrostatic head, DWR ratings, if given at all, are usually contained in the small print of a product’s specifications. Below is a rough guide to deciphering any ratings you should happen to come across:

  • 80 points/10 washes - The bare minimum for classification as DWR in most outerwear 
  • 80 points/20 washes - The typical DWR rating for water-resistant products for most outdoor industry brands
  • 80 points/50+ - Exceptional water repellency, usually used in either very high-end waterproof products or garments which lack a waterproof membrane and rely only on DWR for water resistance

Issues with DWRs

Those buying DWR products should be aware that are not without their drawbacks, most notably the use of chemicals, maintenance issues, and the need for reapplication of the DWR coating. 

Chemicals

Although in recent years many brands committed to eliminating or reducing the use of harmful chemicals from their garments, a study published as recently as 2015 found 36 out of 40 outdoor products to contain toxic perfluorinated compounds (PFCs).

PFCs, which have been linked to health issues such reproductive and developmental problems and cancer, are chemicals used in many DWR finishes that do not degrade, are very slow to eliminate from humans and other animals, and in many cases last indefinitely in the environment.

In 2015, 200 scientists signed the Madrid Statement, which highlighted the harmful effects of PFCs and called for the toxins to be phased out. Although some big brands were quick to comply, others such as the North Face and Mammut still use PFCs in newly released products, despite having vowed to phase them out of usage by 2020.

Maintenance & Reapplication

Unlike waterproof membranes such as Gore-Tex, eVent, or Pertex Shield+, the water resistant component in DWR products are durable, not indefinite. After prolonged usage and washing, a number of factors such as dirt, grease, sweat, abrasion, and weather exposure can and will reduce DWR efficiency and effectiveness.

To reduce the deterioration of a DWR coating, regular washing with additive-free a DWR detergent is advisable. After every 10-20 washes, reapplying the coating with a spray-on treatment such as Revivex or Nikwax TX Direct Spray-On (see video below) or wash-in treatment such as Nikwax TX Direct Wash-In will restore the coating’s effectiveness to levels similar to those at the time of purchase.

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what is hydrostatic head cover

Hydrostatic Head: A Layman’s Guide

WHAT DOES HYDROSTATIC HEAD MEAN?

WHAT doeS HYDROSTATIC HEAD (HH) mean?

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Buying gear and clothes for the great outdoors is a touch more complicated and consequential that picking up our “civvy” gear for kicking about town. While getting a gear purchase wrong for the pub on Friday night may result in a spot of light ridicule and an extended stint of singledom, for the outdoors the payback for a poor purchase could be far more severe (If you are unsure what to wear, then check out our hiking clothing guide).

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As such, when it comes to the “biggies” of our backcountry belongings — if you want the best waterproof hiking pants, jackets, tents, and groundsheets — we want to know we’re spending our would-be beer money on something that’s fit to task. But beyond the breezy and bold claims of the marketing departments, how are we to know what’s going to work?

Enter the acronym! In Part One of our Hiking Duds Decoded Series, we uncovered the mysteries and exposed the blessings of "What is DWR?"; in part two, we turn our attention to the equally enigmatic HH — Hydrostatic Head.

Below, we aim to demystify the mystified with a thorough, straight-talking lowdown on the workings and wonders of HH, starting off with a few facts and figures before moving onto an explanation of how these can be interpreted practically for the everyday hiker.

What is Hydrostatic Head?

The acronym HH stands for Hydrostatic Head. In a few words, hydrostatic head refers to the tests and subsequent ratings used to determine and denote the waterproofing capacity of any textile, most commonly jackets, tents, tarps, and groundsheets. (Note: there is a difference between water resistant and waterproof - these are not interchangeable terms).

Pro Tip: Waterproof vs Breathability

When buying any waterproof product, be aware that high waterproofing capacity may equate to a correspondent loss of breathability.

Manufacturers use these tests and ratings to differentiate between varying levels of waterproofing. Whereas the label “waterproof” was once a one-size-fits-all umbrella term, these days — and thanks to HH testing — we can now distinguish between products and garments that are very waterproof and those that are only marginally waterproof.

How is Hydrostatic Head Tested?

The HH rating of any product is tested by applying water pressure (i.e. hydrostatic head pressure) on the surface of the fabric and measuring how much it can withstand before allowing water to pass through.

An open-ended laboratory test tube is placed on top of the fabric and filled with water. As the water level rises, the pressure on the fabric increases correspondingly. The point at which the fabric begins to allow water to seep through is what is used to determine its hydrostatic head, which is given in millimeters. For example: if the fabric begins to leak with 10,000mm of water pressure, then its HH is 10,000mm. 

How to Translate HH into Something Practical

For the purposes of the user, HH can be translated using the following guidelines:

Tents

1,000 HH = The minimal legal requirement to call a tent “waterproof” (but, in practice, found only in very basic tents capable of withstanding the very lightest of showers).

1,500mm = A ballpark figure for summer tents when the worst conditions you expect to encounter are light showers. Prone to leakage after extended exposure to moderate rainfall.

2,000mm = The most common rating for three-season tents and capable of withstanding a combination of heavy rain and driving wind.

3,000+ mm = The proverbial “bombproof” of backcountry parlance, tents with this HH rating are commonly of the expedition and alpine variety and are able to withstand heavy downpours, gale-force winds, and the pressure of objects or bodies pressed against the fabric (which makes lower-rated models prone to leakage).

Pro Tip: It's not just about HH

Additional factors contribute to a product’s overall waterproofing, most notably taped seams, storm flaps on the pockets, AquaGuard zippers (see video below), and reinforced waterproofing in pressure points such as the knees and shoulders

Groundsheets

Groundsheets are subject to more pressure applied upon them by the bodyweight of a tent’s occupants and other equipment inside the tent, both of which make them more liable to leakage. As such, a higher HH (in the region of 3,000mm and upwards) is required to ensure reliable waterproofing.

Jackets 

In the UK, a mere 1,500 HH rating is required for a jacket to be advertised as ‘waterproof’. In all but a few cases, however, jackets marketed as out-and-out shell layers boast far higher figures. The following guidelines offer an idea of how these figures translate into performance in the field:

10,000mm = Suitable for light rain showers but liable to leak at pressure points where the straps of your backpack are in contact with the jacket (the shoulders, back, and belt area)

20,000mm = Adequate for heavy rain showers and is usually a more breathable fabric than those with a higher HH rating

30,000mm = The HH rating used by manufacturers such as eVent (in DV Expedition models), garments with this rating provide solid waterproofing in even the heaviest downpours and are very unlikely to leak even at pressure points or in the most extreme conditions. On the downside, 30,000mm-rated fabrics tend to sacrifice breathability and this degree of waterproofing is considered overkill by many other garment manufacturers.

HH of Various Brands

Different brands use different HH ratings for waterproof garments and camping products.

Goretex

Despite being a market-leader in waterproof products, Gore-Tex are not great fans of HH testing and do not use it to evaluate the waterproofing capacity of their fabrics. Instead, the folks at Gore put their products through a very rigorous series of tests that are designed to simulate a variety of rain conditions — a process they believe to offer a more practical and thorough examination of a garment’s waterproof performance. While this may seem like a cop out, Gore’s GUARANTEED TO KEEP YOU DRY™ promise shows just how much trust they place in their product and testing process.

eVent

eVent currently offers 3 variations of waterproof fabric which each have different Hydrostatic Head ratings:

  • eVent DV Expedition — 30,000mm: All but impregnable in terms of waterproofing but slightly lacking in breathability compared to the Alpine and Storm varieties (below)
  • eVent DV Alpine — 20,000mm: A performance-oriented, 3-layer laminate that strikes a perfect balance between waterproofing and breathability
  • eVent DV Storm — 10,000mm: Places an emphasis on breathability over waterproofing, doing the former exceptionally well and the latter well enough to deal with moderate showers

Pertex

Pertex comes in two forms of waterproof fabric: Pertex Shield and Pertex Shield Pro.

  • Pertex Shield fabrics focus more on breathability than water resistance and use 2, 2.5, and 3-layer constructions with hydrostatic head ratings in the region of 10,000mm
  • Pertex Shield Pro is intended for use in more extreme conditions and uses a highly breathable, 3-layer waterproof construction with hydrostatic head ratings of around 20,000mm

Polartec

Polartec NeoShell products are made with a cutting-edge blend of softshell flexibility and stretch and hardshell waterproofing. While the HH rating of Neoshell garments is a relatively low 10,000mm, this fabric is all about providing maximum breathability without sacrificing waterproof performance and resistance. Ideal for highly aerobic activities such as mountaineering, ski mountaineering, ski touring, and mountain running or fell running.

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How to Layer Clothes Title

How to Layer Clothes in Cold Weather

STAYING WARM: HOW TO LAYER CLOTHES IN COLD WEATHER

STAYING WARM: HOW TO LAYER CLOTHES IN COLD WEATHER

Article Summary

QUICK TIPS: DO'S & DON'TS

Legendary English cartographer, mountaineer, and fellwalker Alfred Wainwright once said “there’s no such thing as bad weather, only unsuitable clothing.” Mr. Wainwright probably never spent many winters in Patagonia, monsoon seasons in Himachal Pradesh, nor had the pleasure of snowshoeing through a blizzard in the North Cascades. He almost certainly never made the short trip over the border to neighboring, rain-lashed, and windswept Scotland. That said, his words contain a degree of wisdom from which all of us cold-weather wanderers can undoubtedly learn. 

Back in the day, staying warm in the outdoors meant cocooning yourself in the biggest and bulkiest gear you could get your hands on. The results ranged from a vaguely aquatic, sauna-like stuffiness to feeling like you had been mummified in several pounds of cellophane. Thankfully, times have changed, and our knowledge of high-performing materials and our own bodies has evolved.

At the heart of this ‘evolution’ is the layering system.

In this article, we’re going to delve into the layering system’s finer details and give you the lowdown on how to dress for cold weather in the outdoors. It’s an easy skill to learn, and one that can make the difference between a fun, safe day out and an utterly miserable one.

Before we get down to the science and skinny on layering for cold weather, let’s first take a quick look at the more standout take-homes this article will cover.

Do

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    Wear a high-wicking base layer for effective moisture management
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    Make sure you keep yourself dry both inside and out — sweat and precipitation can be equally effective in decreasing your core temperature
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    Remember that breathability in any layer is just as important as insulation, particularly with more active backcountry activities
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    Shoot a size up with shell layers to allow room for your base layer and insulating layer

Don't

  • Wear cotton. Ever. Period!
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    Allow yourself to work up a sweat before shedding a layer — that sweat can quickly cool off and increase the risk of hypothermia or a bad case of the chills
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    Be tempted to think the layering system is just a consumerist fad conceived to empty our wallets

Learn from the Pros - Mountaineering Legend Ed Viesturs explaining his take on the layering system.

Layering Clothing for Protection Against the Elements

To a certain extent, Alfred Wainwright’s oft-quoted aphorism has the makings of a ‘must-remember’ motto for all mountain-goers. Whether we’re on a remote Munro in the Scottish Highlands, trekking the Annapurna Circuit, or wandering the wilds of Alaska, the weather’s vagaries and inclemencies all have one thing in common — their potential for harm and general harassment can be seriously reduced if we do our homework and know how to layer clothes for cold weather.

So, how exactly is it done?

Couple hiking with dog in winter mountains

Your Base Layer(s): Moisture Management

The most important thing to remember when choosing a base layer is that its main purpose is wicking and moisture management, not warmth.

In a nutshell, the base layer helps to regulate body temperature by capturing perspiration and shifting (‘wicking’) it away from the body. In doing so, it assists in keeping you dry and reduces the chance of hypothermia in colder conditions by ensuring that moisture isn’t allowed to turn cold and lower your core temperature.

Pro Tip: Sizing

​Sizing is crucial to effective layering, particularly with outer layers. When buying your outer layers, remember they will often be worn on top of two or three lower layers — if in doubt, go a size up

Base layers come in a variety of forms and fabrics. The most effective of these include:

Merino Wool

This has, in recent years, become the go-to garb for countless outdoor enthusiasts. It breathes well, retains heat even when wet, and downright refuses to stink up, no matter how hard you and your sudoriferous glands may try. On the downside, merino products are usually very pricey and often lack the durability and ruggedness of synthetic base layers.

Synthetic Materials

Common types of synthetic base layer fabrics include Polygiene, Lifa, Omni-Wick, Capilene, Polartec Powerdry, and Polyester-Polypropylene blends. Generally speaking, most products made with these fabrics are much cheaper than merino and wick just as well. On the downside, they are much more prone to smelliness given a few hours of outdoor action, particularly Lifa and Capilene.

Pro Tip: NEVER Wear Cotton

The most important thing to avoid when choosing a base layer is any product that contains cotton. Is cotton a good insulator when wet? Cotton loses its insulating capability when wet, as demonstrated in the video below from Cotswold Outdoors.

If that doesn’t manage to put you off cotton, maybe this article from Gizmodo (tellingly entitled ‘Why Cotton Kills’) will do the job!

Your Middle Layer: Insulation

The mid layer is all about warmth. It works by keeping your body heat trapped close to your body and providing a ‘buffer’ against the ambient air. The most common materials used in insulating mid layers are down, wool, fleece, and a variety of other synthetic fabrics. Whether you choose to use one or two mid layers will depend on how fast you’re moving and just how cold the weather is on your hike. 

Down

Down is a very effective insulator in dry and cold conditions and also offers a great warmth-to-weight ratio. On the downside (no pun intended!), it’s pricey and all but useless when wet. The pros and cons of down-filled jackets and synthetic-filled jackets are covered in detail in the video below from Go Outdoors.

Water-Resistant Down 

Recently, a few brands have sought to remedy down’s only drawback by creating products with improved water-resistance. These are pretty much the holy grail of mid-layer insulation, but to get your hand’s on one will, for most, require approaching a bank for a small loan or hitting it up for a robbery.

Wool

Wool has undergone something of a revival in outdoor clothing in recent years thanks to brands such as Icebreaker, Redram, and Smartwool. And it’s not just base layers. Many manufacturers are now adding heavier, thicker wool items to their mid layer collections. These layers offer the same wicking capabilities as the base layers but usually not the same wind-proofing as synthetic or down mid layers when worn without a shell.

Pro Tip: Extra Layers

Your extremities are only likely to suffer if the rest of your clothing is inadequate — if your hands are cold, throw on another jacket or mid layer

Fleece

‘Pile’ fleece products now come in a wide range of styles that vary from brand to brand — Polartec, Pontetorto Tecnopile, and Windstopper are just a few examples. Fleece is slightly less compressible than other mid layer fabrics but is a cheap, reliable, high-performing option that can insulate even when wet.

Active man hiking in the mountains. Patagonia, Mount Fitz Roy

Your Shell Layer: Weather Protection 

The shell layer or outer layer is all about keeping meteorological miscreants — rain, wind, sleet, snow — where you’d prefer them to be…outside. That said, in order for our lower layers to perform effectively, the shell layer must also offer some degree of breathability. Ultimately, the overall efficiency of a shell layer rests on finding a balance between weatherproofing and breathability. This point is further demonstrated in this nigh on exhaustive analysis of shell layers from UK Climbing.

Pro Tip: Know Your Waterproofing

When buying an outer shell, be aware that there are varying levels of water resistance. Nowadays, most jackets and waterproof hiking pants come with a waterproof rating given as a number somewhere between 0 and 20,000mm. This number refers to the amount of liquid the materials can withstand (also called hydrostatic head pressure) in test conditions by measuring a one-inch diameter of fabric: the higher the number, the more waterproof the jacket.

Also make sure you understand the difference between waterproof and water resistant.

The most waterproof breathable shells use fabrics such as Gore-Tex, eVent, or NeoShell, all of which allow the vapor from sweat to escape but also maintain excellent waterproofing capabilities due to their DWR coated exterior.  

Pro Tip: It's Not Just About the Material

Several other features contribute to a shell layer’s overall waterproofing capacities (sealed seams and water-resistant zips, for example) and breathability (pit-zips, thigh zips, velcro cuffs, adjustable waist).

A lot has been written about the difference between hardshells and softshells. Although many softshells are now being made with hardshell-like features (improved weather-resistance, for example) and vice versa (several hardshells now sport flexible softshell inserts and boast insulating liners), the gist is this: hardshells generally offer better waterproofing and softshells offer more flexibility and better insulation. This page from Gore-Tex analyzes the hardshell vs. softshell question in much more detail, weighing up the pros and cons or each before offering tips on deciding which one’s likely to be best for you.

Additional Gear

The bits and bobs of outdoor apparel are just as important as the nuts and bolts. Before heading out to let the elements do with you as they will, a little bit of know-how about gloves, hats, socks, boots, and shoes could save you many pains and tribulations.

Gloves

Depending on your activity, the type of glove you need will vary greatly: 

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    ​Hikers should always try to wear two pairs in chilly conditions: a thicker, insulated glove for warmth and a thinner liner underneath. This ensures that even when taking the outer glove off to take photos or adjust gear your skin is not exposed
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    Alpinists or mountaineers should aim for something a bit more dexterous (guide or gauntlet style, for example) to allow for maneuverability with ropes and technical gear, and should also carry a second, meatier pair of fleece or down-lined gloves in case of an emergency
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    Those out doing photography, hunting, snowmobiling, or fishing need to account for the amount of time they will be stationary and choose their gloves accordingly. The ideal setup would be a very thick pair of mitts with a thin liner underneath to allow for more nimble finger-work when need be

Pro Tip: Spares

Carry spare gloves close to your body to keep them warm (and never lay either pair down!) and always carry a second pair of socks

Hats

Folk wisdom and our grandmothers once told us that 45% of our body heat is lost through our heads. While that myth has now been well and truly debunked, there’s no doubt that a chilled cranium is something most of us would prefer to avoid. To do so, we’d recommend a hat that is breathable, itch-free, and adequately insulated. Merino and fleece hats or beanies are both good options and the decision is mostly a matter of personal choice. To help you make that choice, this article from The Clymb offers a very thorough examination of the various fabrics and features available.

At a bare minimum take a good hiking hat for protection from the sun. In spite of the chilly temperatures, it is often quite easy to get sunburnt. Particularly if you are at higher elevations or there is a lot of snow cover.

Hiking with Dogs 2

Socks

Being one of the sweatier portions of our anatomy, our feet need to be taken care of as much as any other body part. As with other layers, avoid cotton like the plague. We’d recommend merino or hybrid varieties such as those produced by Icebreaker, Bridgedale, or Wundersocks, all of which do warmth and wicking particularly well. Other high-performers are covered in our guide to the Best Hiking Socks.

Boots

Matching your boots to your activity is the key, as is finding a good balance between performance and warmth. Most hikers can get away with using one pair of light weight hiking boots throughout the year by doubling up their socks with a thin liner in winter. For extreme weather hikes or more stationary activities, however, we’d recommend a heavier winter boot with a good insulating layer.

Pro Tip: It's Not Just About the Material

Once your boots get wet, drying them could take a matter of days. If conditions are wet or you’re hiking in snow, always throw on a pair of gaiters.

Always Stay Dry

When we’re out hiking, getting cold in itself isn’t a huge problem — the real danger lies in getting wet. Whether we get caught in a rain shower or are working up a sweat, any moisture retained by our clothing can put us at risk of hypothermia, particularly if we stop moving for any length of time. While avoiding airborne moisture is the job of our shell layers, build-ups of the bodily stuff can be reduced by following these tips:

Pro Tip: Hot Chocolate

​Carry a flask of hot drinks — if there’s no roaring fire or sauna in the immediate vicinity when you get the chills, sugary, warm liquids are the quickest way to raise your core temperature

Pace Yourself

Try to maintain a steady pace at which you are not breaking a sweat. If you start to feel a bit of leakage in the oxters or elsewhere, slow down, shed a layer quickly, or…

Use Zips and Roll Up Sleeves

If you don’t want to spend all day taking layers on and off, make use of your gear’s built-in air con delivery systems — the zips and sleeves. When buying an outer shell, consider plumping for jackets that have pit zips and adjustable cuffs and pants that have ventilation zips in the thigh.

Take Breaks

One very simple way to avoid working up a potentially dangerous sweat is to take frequent breaks. Every half hour or so, pause briefly to let your body cool down ever so slightly and then move on. These breaks should be limited to 2 or 3 minutes because if you sweat extensively in the period between breaks, as little as five minutes can be enough for hypothermia to strike.

What to Wear When Doing Different Activities

A one-size-fits-all, generalized approach to layering fails to account for the specific demands of different activities. Depending on what you’re getting up to in the wild, a few tweaks and adaptations are required to optimize your layering system’s efficiency.

Below, we’ll look at how it’s done with a short guide on how to layer clothes for two broad categories of activity: active and less active.

Active

Active sports include hiking, mountaineering, ski mountaineering, and cross-country skiing. In each of these activities, working up a sweat is somewhat inevitable. To ensure that sweat doesn’t ruin our day — or worse — getting your layering spot-on is vitally important. 

hiking in snowshoes2

A high-wicking base layer shirt and pair of pants or hiking leggings should form the base of any cold-weather getup. The mid layer and shell for more active backcountry pursuits will depend largely on the conditions. In cold, dry conditions, you can choose to wear two mid layers up top or a single mid layer with the outer shell. In wetter conditions, your best bet is always to wear a single mid layer up top and the outer shell pants directly on top of the base layer if conditions aren’t cold enough to warrant a mid layer between the two. The video below from The Outdoor Gear Review offers a general overview of layering for more intensive outdoor activities as well as handful of useful insights on optimizing your cold-weather hiking kit. Check out our guide for a fuller review on what to wear hiking.

Less Active

Less active sports include hunting, outdoor photography, fishing, snowmobiling, and ice-climbing (we’re thinking of those long periods of inactivity at belay points).

The amount of time spent stationary or nearly stationary in each of these activities means insulation takes priority over breathability and wicking capabilities. That said, the fundamentals of the layering system remain.   

ice-climbers-1247613_1920

On top of the standard base layer (shirt and pants), these activities require a heavier mid layer — substantial fleece-lined, synthetic, or down pants and tops. Mid layer pants then can be topped off with an outer shell. Up top, a second mid layer providing added insulation is a good idea prior to finishing off the ensemble with a weather-proof outer shell, two pairs of gloves (liner and insulated), two pairs of socks (liner and a thicker pair), and a hat.

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