Waterproof and Breathable Outdoor Clothing.
A few years ago I wrote an article on waterproof outdoor clothing for the website of an outdoor retailer that was to be used as an online consumer guide and internally as a staff training document. https://www.bebee.com/producer/@neil-smith/waterproof-clothing . Re-reading it recently I was struck by a couple of points: one, unsurprisingly enough, was that some aspects of rainwear technology have moved on a little since 2007. Another was that as the original had to be brand neutral there were some constraints on what could be written in case some of the retailer’s suppliers got annoyed with any perceived criticism. Given current developments such a stance leaves a few gaps in the original picture and that sort of thing is always going to leave an itch needing scratched. The final thing I took away from the original is that it is more complicated than it needs to be. The original categories reflected how most manufacturers and stores would categorise their stock. It made sense in the event of someone strolling around the rainwear department with a printout of the article. The categories on the sheet would roughly match the layout on the walls in front of their eyes. (No smartphones or tablets in 2007 we had to print things out on stuff called paper. Look it up kids). With the benefit of hindsight and a few more years of experience I reckoned that a slightly different approach would probably be more realistic and useful to the majority of shoppers. Hopefully you the reader will agree and that you find this a useful and possibly interesting guide.
Until the late nineteen seventies waterproof rainwear used in the outdoors consisted of pretty heavy duty, nylon fabric coated plentifully with a layer of either polyurethane or neoprene on the inside. Jackets or cagoules as they were known in my youth were over the head styles that often reached down as far as the knees. Rainpants when worn at all had a decidedly ‘70s flared look. Zips were distrusted as unreliable and prone to leaking so if they were used at all they were often backed up with gusseted material. When was the last time you bought a jacket with a neck gusset?
Such garments were usually very good at keeping the rain out and because the fabric used was so heavy, thick and stiff the durability was generally excellent. They did however come with a huge amount of downside. They were waterproof in both directions. Rain couldn’t get in and sweat couldn’t get out. The result was that the mountain walker got wet from one source or other no matter what. Gear articles in magazines and books such as the Spur book of walking gave advice based on the idea that it was safer to be wet and warm rather than wet and cold so keep your waterproofs on.
The decision to don rainwear whilst out on the hill was not one to be taken lightly. The effort of unpacking and pulling these garments over one’s head meant that a pause to change could take quite some time for even a small group of people. Walkers caught in a series of showers had to make a judgment call as to whether it was rainy enough to make it worth getting suited up in raingear or just to continue, hoping that the shower would pass and that one would dry off in due course. Some days there was just no right answer.
It was not uncommon to pass groups of people where different choices had been made and note that some were drenched in breeches and woolly shirts whilst others were drenched in sweat inside a nylon bin liner with sleeves. Drenched however was often the ground state of being for a walker on a damp day. Comfort was something that was regularly sacrificed. No-one could possibly have enjoyed spending a wet day walking in state of the art waterproof clothing in the mid-seventies.
In 1976 WL Gore and Co. introduced a new fabric to the North American market. Gore-Tex jackets were light, flexible and best of all BREATHABLE. Gore-Tex was the first fabric brought to market that allowed perspiration to pass through from inside to outside. This meant that the wearer now could experience a degree of comfort in wet weather conditions unmatched by traditional waterproofs. Gore-Tex was significantly more expensive than the old school alternatives yet this cost difference presented no obstacle to change. Almost overnight professional users and hobbyists with the funds switched to the new wonder material. Berghaus were Gore’s pioneer clothing manufacturers in Europe the following year and their products were soon an incredibly common sight on the hills of Scotland. What really caused an industry revolution however was that people started wearing these jackets away from the mountain environment. News and sports reporters showed up on our screens every night in branded rainwear and outdoor clothing had begun the journey from the wilderness to the high street. Clearly for any other fabric manufacturer to compete there had to be a serious change in the product offering and the next few years saw an outpouring of alternatives all offering degrees of breathability and all noticeably more expensive than that which had gone before.
From the outset it was clear that manufacturers, commentators and magazine writers were willing to grossly overstate the benefits of their products. All of the early fabrics had serious problems and none of them offered the feeling of walking around in only a light shirt which was certainly implied even if not explicitly stated in much of the marketing. The wide tape used to cover and seal the stitched seams of garments reduced the potential breathability. Early Gore products were seriously prone to delamination as were Polyurethane coatings such as Cyclone and others made by rival companies. Customers were generally less miffed than might be expected by this due to the increased comfort levels and the excellent nature of the guarantees offered by manufacturers who replaced faulty product time and again. As quality improved the guarantees gradually became less generous. Despite the early problems however it took no time at all for breathable to be the only game in town. Nowadays only the cheapest jackets are made with non-breathable fabrics.
What does “Breathable” actually mean?
So far as the outdoor garment industry is concerned the term “Breathable” has a fairly specific meaning and refers to a measurement known as the “Moisture vapour transmission rate” or MVTR. This test measures how much moisture, in the form of steam passes through a sample of a fabric in a period of twenty four hours. The test has become the industry standard and the results, expressed in grammes per square metre are much quoted by manufacturers, gear reviewers and saloon bar blowhards alike. It has though, a few problems which reduce its relevance in the real world outside the lab. Firstly if your body is operating at one hundred degrees Celsius then you have way more to worry about than the performance of your jacket. A test which operates at normal core temperature for humans would be more relevant and many other tests do exist giving a more nuanced view of fabric performance over different timescales and under different conditions but these are much less popular than MVTR with manufacturers as the results are usually less flattering. High external humidity, which is never an issue in a lab, reduces the rate at which moisture moves from the inside to the outside of a garment. A jacket will move moisture better in the dry atmosphere of Arizona than in the damp, humid air of Wicklow or the Scottish Highlands. In real life a waterproof jacket will see more use in the latter places than it will in the south western US so the breathability level quoted should be mentally edited down in any location with a generally high level of atmospheric humidity. Thicker, heavy duty fabrics will score worse than thin fabrics with the same membrane or coating. Choosing a high MVTR garment may lead to inadvertently choosing a less durable one as the lightest thinnest materials will generally not wear as well. Because the MVTR is based on fabric samples rather than complete garments it takes no account of design which can also affect the breathability and user comfort. A jacket with a lot of stitching for purposes of decoration or enhanced movement will also have more seam tape which reduces breathability, sometimes dramatically so. A jacket with pit zips will be much more comfortable to wear on a warm, wet day but the existence of such a feature has no effect on the MVTR test. Despite all the objections that have cropped up over the years it is undoubtedly true that the MVTR does supply a common, uniform standard for waterproof and breathable fabrics. It is not perfect and may not tell the whole story but it certainly offers a decent starting point.
Apart from rare examples of manufacturing errors or fabrics from a faulty batch it can be stated that all waterproof garments are actually waterproof. Making fabrics waterproof is old technology and companies have become very good at it. Coat the fabric in PU or cover it with an impermeable membrane and you have a waterproof material. When this is cut to shape and size and stitched together the holes made by the sewing machine have to be taped over with an impermeable tape. When this is done the waterproof fabric has become a waterproof garment. As mentioned earlier this is old technology and the industry has become very good at it. It is possible to buy a budget Regatta jacket for under €50 and it will be no more or less waterproof than the top of the heap €750 Arcteryx jacket. Waterproof means no moisture gets through from the outside and this is easy to do. Better than “100% Waterproof” doesn’t exist. Only professional footballers give 110%. The difference between these examples doesn’t lie in the waterproofing, it is more that the dearer garment will offer a much better fit, more performance features such as pit zips or hood adjustment, significantly improved mobility and noticeably enhanced breathability. It’s not that there are no differences between them. The differences are in fact massive it is just that the level of “waterproofness” isn’t one of them.
Pretty much every waterproof/breathable garment on the market today is markedly superior to anything that was available in the mid 1970s. Most modern gear is lighter, more comfortable, more flexible and offers better vision than the jackets of yesteryear. They are however “Better” not “Magic”. When wearing any waterproof garment there is a good chance that the user will end up wet to some degree through perspiration. The more effort you put in, the more sweat you produce and the faster you overload the material’s capacity to move it to the outside of the garment. Once sweat starts condensing on the inside of a jacket or rainpant it is only a matter of time before the wearer becomes damp. The Better the fabric, the better the design and the more venting options you have the less likely you are to reach saturation point but no current option is perfect. For a lot of mountain and trail running it is better to avoid waterproofs altogether when possible and rely on windproof and softshell garments in order to improve breathability in sweatier, aerobic activities.
Types of waterproofing
There are performance rainjackets for hillwalkers, climbers, runners, cyclists, golfers and skiers many other pursuits. Most of these garments are cut from a fabric consisting of a sheet of nylon or polyester with a waterproof coating or membrane on the inside and a DWR (Durable, Water Repellent) coating on the outside. The fabric provides the structure and strength, the internal membrane or coating provides the waterproofing and the DWR provides a micro climate on the surface of the fabric that keeps rain beading off and allows moisture to escape to the outside. For mountain walking most jackets and pants are made from nylons. These are stronger than polyesters and usually a bit more durable but generally don’t feel as nice to the touch and make more noise when moving. Polyesters can be “peached” or made slightly fuzzy to create a softer, quieter garment and they hold their colour better over time due to superior UV resistance. Both fabrics work well and it would be untrue to say that top end gear is exclusively nylon or that golf clothing is exclusively polyester. One of the best mountain/adventure jackets on the market is made from a polyester fabric and some of the cheapest walking jackets are made from nylon but it is the case generally that most hiking gear is nylon based.
Membranes are a very thin sheet of waterproof material bonded to a face fabric. The best known of these is Gore-Tex in its various guises but other well known options are E-Vent, Sympatex and Dry.Q. Gore-Tex is always labelled as such no matter who makes the garment. E-Vent and Sympatex can appear unheralded or marked as a manufacturer’s own brand membrane. Dry.Q is a PTFE membrane with a more porous structure to enhance breathability developed by the makers of eVent exclusively for Mountain Hard Wear.
Gore-Tex, eVent and Dry.Q are microporous membranes. They are basically full of microscopically small holes which allow water vapour to escape but which are too small for liquid water to penetrate. Gore-Tex is also backed with a polyurethane layer to protect against contamination and membrane breakdown. This is effective but reduces breathability. eVent is a newer PTFE membrane and gets by without the PU coating. My own admittedly limited experience of using eVent jackets would suggest that it is not as reliable in the long term as Gore-Tex but is certainly more breathable and much more comfortable to wear for energetic activities. DryQ is a more “spacious” airier PTFE membrane and the high levels of breathability make it a great choice for adrenaline athletes and anyone planning on working up a serious sweat out on the hill. It does not however come in a budget version so be prepared to pay for the performance. In the last few years, Gore has launched a new version of their membrane called Active shell to address the issue of reduced breathability compared to their competition. This is indeed more breathable and is usually used in garments with built in venting to improve performance still further but the membrane itself is much thinner than the original so once again better performance at the high end of the activity range comes at the cost of durability as well as at the cost of cost. Sympatex is a Polyether Ester. A closed membrane with good durability and a good natural stretch. This allows for more comfortable garments with a bit of give in the fit. Sympatex requires a bit less washing than the others to maintain a level of breathability but that level is a bit less to start with. Depending on the design of the garment this may not be an issue. Pit zips and long leg zips allow good air flow and enhance any garment’s comfort level. Even if it doesn’t hit the heights of performance it is not particularly far behind and even top end Sympatex garments rarely require crazy money.
Coatings. In reference to waterproof/breathable coatings we are almost always referring to polyurethane. Polyurethane sometimes seems to be the mainstay of the outdoor industry. It is used in footwear for midsoles, soles and waterproof linings. It features in backpacks, clothing and tents and undoubtedly a whole lot more besides. PU coated fabrics are easier to manufacture and so the finished products tend to cost less than most membranes. Lots of high end outdoor brands offer a choice of virtually identical garments one in a branded membrane and the other produced with an own brand PU coated fabric. Usually although not always, the only performance difference is a higher level of breathability. Whether the improvement is sufficient to warrant the extra is a question that the likes of North Face and Mountain Equipment are happy to leave to the customer. The biggest problem with buying jackets made like this is that a lot of brands see PU coated garments as their budget offering so it can be hard to find things like pit zips or good pocket vents but some do so it is worth looking around. As mentioned before good venting features make an enormous improvement in the comfort often far more than paying for a better grade of fabric but with poor features. Brands here are virtually irrelevant as most manufacturers are producing very similar product with very similar performance. Entrant would be quite a well known fabric in the ski market but most of the time a jacket supplier will buy a fabric and label it as an in-house brand. Thus North Face has HyVent, Berghaus have Aquafoil and now AQ2, Columbia has OmniTech and so on ad infinitum through a list of the next hundred outdoor clothing companies that spring to mind. Don’t get me wrong, none of these is a bad fabric in any way it’s just that there is nothing of significance between them in terms of perceived performance and comfort. What they all offer though is a perfectly acceptable level of breathability for less sweaty activities. When the need for greater breathability arises, these will be reliant on venting and they are the kind of jackets that may not come with a lot of venting options. I would say though that a cheaper fabric with better venting would in my opinion be more comfortable than a more expensive fabric with rubbish venting. Ask yourself if perspiration is more likely to escape through invisible, microscopic holes or through a great big one under each armpit.
OutDry. This is what Polyurethane becomes when it grows up. Outdry is a bonded PU membrane which has been used in footwear and gloves for the last six years or so. It has been markedly superior to anything else on the market in those areas but it was only in spring 2016 that OutDry appeared in clothing exclusive to Columbia Sportswear the brand owner. On first seeing an OutDry jacket it appears to be inside out. The seam taping is visible and the surface is distinctly shiny. On closer inspection it turns out that the garment is indeed manufactured inside out. The flexible PU membrane is bonded to the outside of the fabric. This utterly eliminates the need for a DWR layer and means that the garment can never “wet out” which happens when the water repellency wears off or is contaminated with dirt and grease. The advantages of this material have as much to do with the method of construction as with the membrane itself. Putting the waterproof bit right on the outside puts it where it is most needed. Initially Outdry is very breathable but probably not quite as breathable as Gore Active shell and certainly not as good as DryQ. The big difference comes after a couple of months of use. Over a fairly short time most waterproof garments lose breathability due to dirt, body salts and atmospheric particles settling on the inside and outside of the fabric. Regular washing cures the problem but most people don’t wash their outdoor rainwear often enough and some never do. Outdry holds its level of breathability really well over an extended period of use with minimal noticeable change in breathability. Currently clothing in OutDry is only available from Columbia Sportswear but presumably over time this construction style will become much more common. It is the first real innovation in the market since the 1970s and represents a genuine improvement in long term performance.
Durable Water Repellent coatings. DWRs are thin coatings of a water repelling substance attached to the exterior of all rainwear with the exception of OutDry garments. Their purpose is to keep the outer face of the fabric dry by making rain bead on the surface and roll off. In doing this they maintain a dry micro climate right on the surface of the fabric which allows perspiration to escape from the inside of the fabric. The name is odd because the one thing I have never found DWRs to be is durable. In my experience they scrape off pretty quickly on rock or foliage and get coated with dirt all too easily. This is hardly the end of the world as rainwear can and should be washed to remove interior and exterior dirt on a regular basis and after washing a re-proofer can be applied by spray or in the washing machine to re-instate the original performance of the DWR. Like most people however I don’t wash my rainwear anywhere near often enough. This means that it is possible to have an expensive, high performance jacket in a snazzy, state of the art fabric and still have all the breathability and comfort of a bin bag. Sweat, salt and microscopic dead skin cells, etc clog up the holes on microporous fabrics. The more breathable a garment then often the more washing is required to maintain the level of breathability. Rainwear which is wetting out feels cold, clammy and horrible all the time. If you don’t wash it you may as well buy a cheaper jacket in the first place. One of the reasons I like my OutDry jacket is that my level of laziness matches its care requirements. Outdoor rainwear is made to be cleaned. Read the label. Low temperature, gentle cycle and a non-detergent soap. Nikwax, Grangers and loads of other companies produce cleaners and re-proofers and a bit of TLC goes a long way. For maximum comfort out on the hill I am a great fan of garments with good venting features. Pants with a long leg zip and press studs down the side allow you to keep the zip open but not have the pants flapping around in the breeze. Pit Zips and pocket vents are the best way to keep air circulating inside a raincoat. Better venting means a drier body and more comfort. Ultimately though a great way to be more comfortable outdoors is to return to the 1970s and only wear your raincoat when it is raining. I regularly pass people on dry days all bundled up for the blizzard that might arrive one day. If you are wearing rainproof clothing on dry days then you are just asking to be soggy. In light showers a light softshell or windproof will be much more comfortable.
If you are in the market for rainwear there are a couple of things to ask yourself before digging into your pocket. Are you going to be wearing the garment in high energy, aerobic activities or gentler walks or even while waiting at the bus stop? How important is it to you not to feel damp from perspiration building up? If you don’t mind a bit of sweat and are going to be home in a couple of hours then maybe high breathability isn’t worth paying extra for. If you need high performance but it is out of your price range then look for good venting features and accept that comfort may be less. Bear in mind that the best and the most expensive are not necessarily the same thing. When buying jacket and pants I almost always get a cheaper pair of rainpants rather than the partner piece to the jacket. Rainpants get worn out far faster than jackets and need replaced more often. This holds whether the pants cost fifty or two hundred and fifty euro. Pants get worn out at the knees, crotch and backside long before most jackets. So long as they have a nice long zip on the leg for access and ventilation then most rainpants will do the job adequately.
The most important thing is to bear in mind that because everything available now is much, much better than everything that was available in the olden days it is hard to get stuff which simply doesn't work at all. In comparison to the heavy, sweaty knee length cagoule of my youth everything seems pretty decent now.
Thanks for reading. All feedback gratefully received.
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