Origins

Outerwear has been around for a long time. As far back as 190,000 years ago people were draping themselves in animal skins in order to survive the cold. They developed technologies such as the needle and thread, made from bone and natural fibers, and used these to sew their pelts into more flattering patterns. This rudimentary outerwear production continued for thousands of years, with only fuzzy evidence of knit or woven textiles until about 6000BC. At this point in time, primitive garments could hardly be considered “outerwear” and were used mostly for decorative purposes.

The real history of outerwear begins with the Vikings. These guys were burly. They lived in the cold, had huge beards, and spoke a language that sounded more like an MMA fight than actual words. You might not expect that these tough guys were actually designers in disguise. They were the first to begin wool production, dying, and pattern making, all in a vain attempt to stay warm.

A shaggy “homespun” Viking Cloak and a very cold Viking

For the next thousand years wool and skins ruled the outerwear world. Even up through WWII, wool and leather were the go-to fabrics for outerwear. What these thousand years lacked in textile technology they made up with in advances in sewing and pattern making. Fully lined garments were the norm with complicated patterns that incorporated multiple types of stiches. Technology such as zippers (all metal at the time) as well as snaps and buttons were used extensively. In 1955 Velcro was patented and the nylon textile industry took off…

History of Gore-Tex and How it all Works

The next piece of the modern outerwear puzzle is a little invention patented under the name “GORE-TEX”.

By the 60’s, nylon fabrics with polyurethane (PU) coatings that were completely waterproof were available. However, these new fabrics lacked any sort of breathability, which made them terrible to use in active wear garments. Enter Bob Gore.

Working with his parent’s company, W.L. Gore & Associates Inc., Bob Gore began experimenting with polytetrafluoroethylene (PTFE), a polymer of carbon and fluorine (in technical speak, four fluorine molecules per each ethylene- in a polymer). Nowadays, it is better known under it’s DuPont brand name, Teflon™.

More specifically, Gore was researching expanded PTFE (ePTFE) for use in plumbing as thread tape and sealant. It turns out that ePTFE stretches quite well and forms a stable (although delicate) web-like structure upon expansion, filled with millions of tiny pores. The “stretchiness” of the ePTFE is what made it commercially viable as a joint sealant. In 1971, the first GORE-TEX products hit the market sealing threads and joints all across the country.

Along with an intense (some might say “nerdy”) interest in chemistry, Gore was also an avid outdoorsman. He was well aware of the waterproof textile technology (or lack thereof) of the time. Once his company had stable sales in the thread

joint/sealant department he turned his attention towards manufacturing a textile that was both waterproof and breathable – and would soon revolutionize the world of technical outerwear.

In 1976, Gore sold his first rain jackets with an ePTFE laminate to the public. He had produced a true waterproof jacket that was also extremely breathable. His customers were ecstatic. Finally they had a jacket that would keep them dry without soaking them in their own, warmth-stealing sweat. Victory!

But not quite – after multiple uses, customers began to report leaks in the fabric. How was this possible? To find out, we first must take a little science lesson…

Gore’s membrane was an extremely thin layer of ePTFE laminated to a nylon face fabric. The ePTFE was hydrophobic, meaning that liquid water was repelled by the surface of the membrane. It also contained millions of tiny pores, which allowed water vapor to easily escape. Genius.

Chemistry aside #1 (feel free to skip): The fluorine shell of the PTFE polymer is neutrally charged. It experiences minimal Van der Waals forces due to the close proximity of each neighboring fluorine molecule and contains a net neutral dipole due to its symmetry. This means the PTFE polymer has a very low surface energy as opposed to the characteristically high surface energy of water (due to enormous intramolecular forces). In order for the ePTFE membrane to “wet out” a liquid with a comparable surface energy must be used. Water, having an extremely high surface energy, cannot “wet out” a layer of ePTFE under normal pressures whereas an alcohol, with low surface energy, could. In short, water will not soak through the membrane because of its high surface energy (commonly called surface tention).

The only way water can get through this membrane is under extremely high pressures. Under this condition, the water could form small enough droplets to fit through the pores of the membrane. Normal pressures from wind-driven rain don’t come close to the pressures required for the membrane to leak, so how did Gore’s first jackets leak?

The answer is simple in the membrane world: fouling. The ePTFE membrane was laminated to the nylon face layer without any sort of protection. Over time the pores in the membrane got clogged with hydrophilic “junk”. This was most likely dominated by ions from the wearer’s sweat. Unfortunately sweat and other similar “junk” particles can have strong intermolecular interactions with the water, thereby greatly raising the surface energy of the ePTFE. Put more simply, this creates a bridge for water to flow through the membrane.

Clearly this was a big problem; one which Bob Gore quickly found a solution for…

Chemistry aside #2: Gore solved his fouling problem by laminating his membrane with a protective layer of polyurethane (PU). Wait, what? Isn’t PU that non-breathable coating on the first waterproof nylon fabrics? As it turns out, Gore was able to use an extremely thin PU layer because the ePTFE formed a great lattice (structure) for the PU to adhere. So you’re thinking, “Who cares how thin it is, doesn’t this defeat the purpose of the ePTFE membrane?” The answer is yes and no.

Non-optional chemistry aside: PU membranes are monolithic, meaning they have no holes. They are solid, so how can water possibly get through this solid layer? The PU membrane is hydrophilic, meaning that water is attracted to its surface. Luckily, it just so happens that if a PU layer is thin enough, water is able to diffuse through the membrane via solid-state diffusion. Individual water vapor molecules adsorb, or chemically bond, to the surface, and pass directly through the membrane to the opposite side. There they can then desorb, or evaporate, through the ePTFE membrane.

The caveat to this process is the driving force. You might ask how the directionality of this phenomenon is controlled. If water vapor can diffuse out, what is keeping water vapor from diffusing in? The answer is this process requires a strong driving force. In this case, the driving force is a concentration gradient. This means that in order for water vapor to diffuse out of the PU membrane, the concentration of water vapor must much be much higher on one side than the other (see illustration below). The greater the concentration gradient across the membrane, the greater the driving force and the greater the mass transfer of water vapor across the membrane.

Illustration of a driving force across a membrane.

Now we will address the concern of the PU layer defeating the purpose of the ePTFE layer. In a way, it does. The PU layer serves a bottleneck for water vapor escape rendering the high breathability of the ePTFE membrane useless. In other ways, it

does not. Without the ePTFE membrane present, it would be extremely difficult (almost impossible) to create a thin enough PU layer that could breathe effectively at all.

Schematic of modern GORE-TEX lamination.

To this day GORE-TEX uses this same technology (albeit in an extremely refined form) for their products. Since then however, many other technologies have sprouted up that achieve similar results. We will discuss those technologies… now!

Modern Technology

As anyone who has ever shopped for outerwear can attest, there are tons of options when it comes to waterproof, breathable technology. GORE-TEX, eVent, H2No, Hyvent, Precip, Gelanots, c-change; the list goes on. So just what are we looking at here? Waterproof breathable fabrics come in a few main derivatives: ePTFE based laminates, PU laminates, and polyester coatings. For the purposes of this article, we will split the technologies into three main categories: GORE-TEX, eVent and the rest (PU laminates) as these technologies dominate the ski/snowboard outerwear industry. We’ve been pretty thorough with GORE-TEX, and for good reason. Its technology forms the basis for the majority of modern waterproof breathable (WP/BR) technology. Now we will cover eVent and PU laminates.

The three major classes of WP/BR membranes.

eVent (pictured above in image “3”) uses an ePTFE membrane just like GORE-TEX. eVent differs in the way it addresses the original GORE-TEX fouling issue. Instead of adding a whole new PU layer on the underside of the ePTFE, eVent uses an oleophobic coating over the ePTFE to keep contaminants away from the membrane. The chemistry is quite complex and out of the scope of this article (the application involves supercritical fluids though, a very interesting branch of chemistry, Google it if you ‘re particularly bored someday). For now, we can think of this coating as a slathering paint on a strainer; the holes of the strainer are all still there, but the original material is now covered by this new coating. In the case of eVent, this prevents the membrane from becoming contaminated.

It seems as if eVent has sidestepped the major breathability bottleneck of GORE-TEX with fundamentally better technology right? Well in short the answer is yes, with a big BUT… We’ll talk about that later in the “Performance Ratings Debunked” section.

The third common waterproof/breathable technology is the PU coating. The same coating that GORE-TEX uses to protect their ePTFE can be used on its own to achieve quite satisfactory results. The laminate ends up being significantly thicker than the layer GORE-TEX uses. However, it does not require diffusion across the ePTFE membrane as an added step in the water vapor transmission process. Most proprietary membranes like Patagonia’s H2No and The North Face’s Hyvent are derivatives of PU membranes. This technology is easy to manufacture, quite durable, and produces good results; a perfect recipe for product viability. Chances are good that if you have a piece of outerwear touted as waterproof/breathable you have a PU laminate or coating in your garment.

DWR, Where the magic happens

So you just bought a jacket that claims 20K waterproofing and you’re stoked. You take it out on the hill and at the end of the day the jacket is heavy with water. Your brand new jacket has “soaked through.” Furious, you call the shop you bought it from and tell them what BS the product claims are and that this jacket isn’t waterproof at all.

But lets look at what is actually happening.

We know that this jacket is probably a PU garment, which means it has a nylon face fabric bonded to the PU layer. We also know the actual waterproof and breathability characteristics come from the laminate and that the nylon face fabric is there for durability and support only.

The “20K” advertised by the manufacturer only references the performance characteristics of the laminate and has nothing to do with the nylon face fabric. The amount of water the nylon face will repel has absolutely nothing to do with the performance of the laminate. So what actually happened to your new jacket?

The jacket you bought came equipped with a poor quality water resistant coating (WR), which allowed moisture to saturate the nylon outer fabric. Your jacket (in all likelihood) never actually leaked, and maintained its advertised “20K” waterproof rating even though it was completely soaked.

The action of the DWR, NOT the laminate!

The WR serves multiple purposes. It keeps your jacket from feeling damp, maintains the breathability of the garment (a soaked through jacket has nearly no breathability), and it keeps your jacket considerably cleaner from water-based dirt and grime. A good WR is absolutely essential for a high performance jacket.

Today manufacturers use what is known as a durable water repellent coating (DWR). This means that the coating won’t wear away as easily as a standard WR. Generally a DWR will retain 80% of its “new” condition after 20 washes.

In short, the waterproof rating and the DWR have absolutely no relation to each other! Even so, people tend to confuse waterproofing performance with DWR performance. To the average (and even above average) consumer, the waterproofness of a material is judged by the DWR, not the laminate. It doesn’t matter how good the laminate is, if the DWR on the fabric is poor, you will not be happy with the performance of your garment!

Along with understanding the differences between laminates and DWRs, it is important to note that a jacket is only breathable as long as its DWR is working effectively. A soaked through textile has little to no breathability.

Companies like GORE-TEX and eVent use a proprietary DWR coating and spend millions of dollars in research to perfect this part of the product. In many ways, it is the most important piece of technology that makes up a waterproof breathable textile. The DWR can make or break a piece of outerwear. Unfortunately it is almost

impossible to know what you will get because there is no standard for measuring the performance of the DWR.

Performance Ratings Debunked

What you might be thinking now: “So if the DWR determines the waterproofness of my outerwear, then what the heck is up with this 20K number for waterproofness?” The answer is that any laminate with a waterproof rating of about 10,000mm will keep you very dry in all but the hardest downpours and gale force winds. However, you will only experience the actual waterproofness of the laminate if your DWR fails. This makes qualifying the importance of the actual performance number very difficult. We will look at how these ratings are actually calculated and then deconstruct their usefulness to the average consumer.

Waterproof ratings, what do they mean?

20,000mm; what the heck does that even mean? This one is deceptively simple. It means that this membrane will not leak when exposed to the pressure generated by a 20,000 mm tall column of water. Simply, all that the waterproof rating means is the membrane can withstand a certain amount of pressure due to water before it leaks. For the curious, 704mm of water = 1psi.

Breathability ratings, do they even mean anything?

15,000g/m2/24 hours… Ummmm, what? This number means that over the course of 24hrs, 15,000 grams of water vapor can pass through a one square meter section of the laminate. Seems pretty simple right? It is not at all a simple number to measure. There is no standardized technique for measuring breathability; therefore companies will often use a test that provides favorable results for their particular product. This makes a comparison of breathability values from different companies completely useless. Various testing procedures can produce huge performance discrepancies. A membrane that tests to 8,000 g/m2/24 hours on one test could produce 28,000 g/m2/24 hours using a different test method. For this reason, many companies do not release these test results. In reality, breathability ratings mean just about nothing, isn’t that comforting?

“So if neither the waterproof rating or the breathability rating are all that useful, then how in the world am I supposed to find a good jacket?” – The now extremely confused consumer.

The bottom line is you have to place your trust in a product at some point, test numbers and marketing can only mislead you in the end. There are two types of choice you may have to make: which manufacturer and which fabric. Manufacturers fall outside the scope of this article, whether it is Burton or Arc’teryx my best advice is to remember you get what you pay for! Fabric on the other hand is something we can talk about:

GORE-TEX

The good: GORE-TEX spends millions of dollars in R&D every year. They make absolutely bomber products and don’t skimp on the technology. GORE-TEX guarantees every product made with their fabrics to be 100% waterproof for the life of the garment – and chances are good you will never have to cash in on that guarantee because their products work really, really well. Gore works with some of the best manufacturers in the game and currently has what many would consider a monopoly on the high-end waterproof/breathable garment market. Their products work, simple as that.

The bad: GORE-TEX is really expensive. Because of their huge influence and their general lack of competition, they can charge extremely high prices for their fabrics. Also, because of the PU layer in their technologies, they cannot breathe as well as their main competitor, eVent. However, GORE-TEX claims this difference in breathability is not noticeable to the consumer and to corroborate that claim, GORE-TEX products often receive rave reviews for their breathability.

eVent

The good: The eVent membrane performs extremely well. It has the best breathability of any technology currently available (even if just barely) and has great waterproofing to match.

The bad: You’d think with a better technology than Gore, that eVent would be a huge contender right? Unfortunately there are many issues that keep eVent from posing a true threat to GORE-TEX fabrics. First is the cost and production; eVent is also extremely expensive. An even bigger issue is in their production. Historically eVent has had trouble meeting production schedules from manufacturers, which is a very large deterrent for business. The next issue is also a manufacturing one; GORE-TEX licenses companies to use their product and it isn’t easy to get a license. If a licensed Gore manufacturer produces a piece using eVent, they can wave goodbye to their Gore license. Companies can’t afford to lose their Gore licenses for a fabric with a slight edge in breathability. Finally eVent’s oleophobic coating can be fouled over time causing leakage through the membrane. eVent garments have to be carefully and frequently washed to maintain their performance as opposed to a GORE-TEX product that is truly waterproof for the life of the garment.

PU, the Workhorse

The good: PU laminates are cheap to produce, are extremely durable, cannot be fouled and are very common (meaning there are a lot of styles to choose from). They can be manufactured to many different specifications so they are found on all sorts of products ranging from price-point Walmart specials to the highest end Patagonia pieces.

The bad: Performance is just not as good as the name brand membranes. In other words, you can only make a standalone PU laminate so thin.

Shell vs. Insulation

So now you know a bit about the technologies involved in outerwear production. The next step is dive a bit into basic outerwear construction. The most common question asked is whether to go for a shell or insulated piece. The designations are pretty simple so I’ll keep this brief.

Shells – Versatility

The good: Shells are extremely versatile and can be made with the most technical constructions. A good shell can be worn in absolutely any weather scenario. It has the flexibility to perform well on a hot day in the pouring rain or in blizzard conditions well below freezing. The only thing you need to modify is your layering.

The 3L Burton Hover jacket. A shell.

The bad: Shells offer little to no inherent insulation. They are not warm and require insulating layers to be warm.

Insulation – Warmth

The good: Insulated outerwear has insulation integrated into the garment’s construction. These pieces can be extremely warm on their own. You don’t have to deal with layer incompatibilities (i.e. a “grabby” fabric versus a “slippery” fabric). It can also be cheaper in the long run considering that good layering can cost a decent amount of money on its own.

The Orage B-Dog, insulated jacket.

The bad: Insulated outerwear is much less versatile then a shell. Too much insulation can cause you to overheat easily, even in cold temperatures. This happens for two reasons. The obvious reason is the jacket has insulation that can not be removed. Not so obviously, the breathability of an insulated jacket is also limited by the breathability of the insulation, regardless of fabric technology. Bottom line, if you need a really warm jacket and are willing to buy multiple jackets for multiple weather conditions, insulated may be for you.

2L vs 3L Shells

Here is a paramount question when purchasing a shell: 2L or 3L? What does that even mean? Well you’re in luck; we’ll break it down for you.

2L – The Original

2L garments are constructed with two layers; a nylon face fabric (generally with a DWR) that is bonded to a WP/BR laminate. 2L garments are always lined with some sort of lining fabric. These linings are generally made of thin nylon or mesh and serve two purposes. First the lining keeps the laminate from direct contact with the skin. This is important because the laminate generally has a plastic feel to it and can be quite uncomfortable. The lining’s main purpose, however, is to protect the laminate. Even though the laminates are engineered to be resistant to fouling, without further protection of the laminate, its durability can suffer greatly. 2L garments are generally constructed with some amount of seam taping. Seam taping keeps water and wind out at the seams but does not breathe.

2L outerwear dominates the market for many reasons. 2L construction lends itself quite well to making insulating garments, which dominate the consumer market (people want their coats to be warm, duh). 2L construction is also less expensive because the technology has been around much longer. The construction of the garments is easier because the lining allows many sewing options with less need for seam taping, and the design is easier because of the ability to work with a lining.

3L – Why does this jacket cost $600?

3L garments are constructed with 3 layers: a nylon face fabric (with a DWR) bonded to a WP/BR laminate; which is bonded to a tricot layer on the inside.

3L construction: blue = nylon face, yellow = WP/BR laminate, orange = tricot liner

3L garments are not constructed with a lining and are therefore often shells. 3L garments generally use the most advanced (and therefore expensive) fabrics and laminates. These fabrics make up some of the most technical pieces of outerwear available. Construction of 3L garments is difficult. Every seam has to be taped or welded and every cut greatly modifies the look of the garment. With seam taping and fabric both being extremely expensive and construction being difficult, 3L garments can be costly pieces of outerwear.

This does leave the question, why go to all the trouble of buying a 3L jacket when you could just buy a 2L jacket instead? There are a few reasons why 3L construction has gained a lot of momentum in the industry lately. First is performance; the addition of the bonded tricot liner increases the breathability of the garment. The tricot is hydrophilic and as you sweat, the tricot preferentially absorbs your sweat and transports it to the laminate so it can diffuse out. Contrast this with a 2L garment where the water vapor has to randomly bump into the laminate while navigating between your skin and the lining to diffuse out. The next advantage is weight. 3L garments can be made without a lining and therefore save a substantial amount of weight when compared to their 2L counterparts. The final advantage is the durability of 3L construction. The addition of the tricot liner adds a significant amount of support and protection for the laminate that is not present in a 2L garment. In short, a 3L garment will have better performance with less weight and be more durable than a comparable 2L design, albeit at about twice the cost.

2.5L – How the heck do you have half a layer?

This is not a very common construction in the world of winter outerwear, but it is a common source of confusion so we’ll briefly touch on it here.

A 2.5L fabric is made up of two and half layers, sort of. It has a nylon face fabric (with a DWR), a WP/BR laminate, and then a printed lining. This printed lining is present for the sake of protecting the laminate but does little to eliminate the clammy plastic feeling of the laminate directly on the skin, hence the designation of a half of a layer. 2.5L fabrics are used on active rainwear because they are easier to produce and end up being lighter than 3L garments, although less comfortable.

What does it all mean?

Well hopefully I have given you the tools and knowledge to make an informed decision when purchasing your next piece of outerwear. The take away in the most general sense; beware of performance ratings and find a good DWR. Beyond that, let personal preference (and your wallet) be your guide on picking out your next piece of outerwear.

Buying outerwear is a journey. It almost always sucks, at least until you are standing on the top of your local hill in a white out, completely comfortable while

your friends are miserable. And after all, outerwear is about comfort, so go out there and get comfy.