Performance Ratings Debunked
So now you’re thinking, “If the DWR determines the waterproofness of my outerwear, then what 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, then deconstruct their usefulness to the average consumer.
Waterproof ratings, what do they mean?
20,000mm: what the hell 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 20,000mm-tall column of water. Simply, all that the waterproof rating means is the membrane can withstand a certain amount of pressure from water before it leaks. (And FYI, 704mm of water = 1 psi.)
Breathability ratings, do they really matter?
This number specifies that over the course of 24 hours, 15,000 grams of water vapor can pass through a one-square-meter section of the laminate. Seems pretty simple, but 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, since 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 pretty much nothing. Isn’t that comforting?
So now the extremely confused consumer asks, “If neither the waterproof rating nor the breathability rating are all that useful, then how in the world am I supposed to find a good jacket?”
Basically, you’re going to have to place your trust in a product at some point; test numbers and marketing may only mislead you in the end. There are two choices you have to make: which manufacturer, and which fabric?
Manufacturers fall outside the scope of this article, but whether it is Burton or Arc’teryx you’re considering, my best advice is to remember you get what you pay for.
Fabric, on the other hand, is something we’ll discuss:
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 that 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 do not breathe as well as their main competitor, eVent. GORE-TEX claims, however, that 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.
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 that, with a better technology than Gore, eVent would be a huge contender in the waterproof / breathable game. Unfortunately, there are many issues that keep eVent from posing a true threat to GORE-TEX fabrics, and the first is the cost: eVent is still extremely expensive.
But an even bigger issue lies in their production: historically, eVent has had trouble meeting production schedules from manufacturers, which is a large deterrent for business.
The third issue is 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 say goodbye to their Gore license, and companies can’t afford to lose their Gore licenses for a fabric with only 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, unlike GORE-TEX products that are 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 (i.e., 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: The performance just isn’t as good as the name brand membrane. Because you can only make a standalone, PU laminate so thin, it is the least breathable membrane of the bunch.