Marmot NanoPro Fabrics vs Gore-Tex Fabrics
I first came across Marmot's new waterproof technologies in one of their buyer's catalogs last year and was really impressed with the waterproof/breathable(WBP) ratings Marmot was advertising. I knew it was going to be a game changer for the average consumer. All of a sudden the majority of Marmot's 2014's jackets were roughly twice as breathable as before with no price increase. This Spring, Marmot released jackets featuring their new NanoPro™ and NanoPro™ MemBrain® fabrics. Below is a chart I made for one to quickly compare the two different waterproofing fabrics from Marmot.
|Marmot NanoPro Membrain vs NanoPro Table|
As you can tell, I love numbers. When it comes to comparing WPB fabrics to other WPB fabrics, numbers don't lie. I don't want subjective descriptions, I want empirical data as to how waterproof, and more importantly to me, how breathable a fabric is. When it comes to standardized testing for breath-ability among fabrics there isn't a single test, there are several. Each standard has their own testing methodologies because the testing parameters for breath-ability varies. Just think about it for a moment: what is breath-ability, how is breath-ability defined, and what factors effect breath-ability (humidity, temperature, air permeability...etc)? I have two purposes for this post:
- To give the general consumer, and particularly those more scientifically inclined, a break down of WPB fabrics
- How Marmot's fabrics compare to Gore-Tex Fabrics
So what does all these numbers mean for you, as the consumer? Well, Marmot was feeling generous and fortunately gave us several different standards to refer to. If you can cross compare different jackets that use the same testing standard, than you can confidently compare the two jackets for breath-ability. Basically, making sure you are comparing apples to apples, not apples to pears.
Before we compare Marmot's new fabrics,let us first understand how just the evaporated heat transfer (RET) test is conducted and what it means. Below is a detailed description from NEMO Equipment on the RET testing methodology:
Think of of the RET value as how much a certain fabric resists transferring heat. A fabric that doesn't breathe very well will have a high RET value. The hotplate will have to provide very little power in order to maintain skin temperature because of how resistant that fabric is to heat loss. A fabric that does breathe very well will have a low RET value. The hotplate will have to provide more power in order to maintain skin temperature because the fabric's minimal resistivity to heat loss. Now that we all understand what a RET value is, let's understand what the Hohenstein RET test is:Evaporative resistance (ISO 11092, ISO 1999, and ASTM F 1868)This test measures the amount of power it takes to keep the plate heated to skin temperature when water vapor is evaporating from the surface of the plate and diffusing through the fabric to the environment. Three 50.8 cm x 50.8 cm square specimens are cut from fabric. A PTFE liquid barrier is placed on the plate to prevent water from contacting the fabric, ensuring that only water vapor contacts the fabric sample. Each test specimen is placed on the horizontal and flat plate orientated with the side of fabric normally encountering more water vapor facing the hot plate. The plate temperature and the air temperature are controlled at 35 ± 0.5°C by a main heater and a set of guard and bucking heaters that eliminate both lateral and axial flow from the main heater. A dew point temperature of 19°C is used to achieve 40% relative humidity. A vertical flow of air from a hood is maintained at 1.0 m/s.
where Re,t= total resistance to evaporative heat transfer provided by the fabric system and air (m²Pa/W), A= area of test speciment (m²), Ps= water vapor pressure at the plate surface (Pa), Pa= water vapor pressure in the air (Pa), and H= power input (W).
Hohenstein added a unique aspect to their testing. They had real people wear garments made with the fabrics of varying Ret values and work out on a treadmill. They gathered the comments of the testers and correlated this to the Ret values of the fabrics and came up with a Comfort Rating System.Some of you may be curious as to how Gore's products compare to Marmot's new fabrics. The only breath-ability test I could find comes from the Hohenstein RET values. I compiled a table below of popular fabrics from Marmot and Gore-tex by their RET value. Unfortunately, only some of the RET values were specifically Hohenstein RET values.
|Table of RET values of Marmot's and Gore's Fabrics|
When it comes whether a fabric is waterproof or not, this too is subjective. For example a water jet cutter uses high pressure water to cut through metal and granite. You would certainly think granite or steel is waterproof, so nothing is necessarily waterproof! Perhaps a better way to parameterize a waterproof fabric would be the average pressure of hurricane rain or the pressure one exerts on a fabric as you sit down on a wet rock?Pressure itself is defined to be:
|Water Column Test Diagram|
A fabric that can withstand 10,000mm column of water is twice as waterproof as a fabric that can withstand a 5,000mm colmn of water. This is only true because the hydro-static pressure is a linear function in this scenario.
|Hydrostatic Pressure equation|
NanoPro and NanoPro Membrain are equally waterproof at a value of 10,000mm, roughly 14.2 PSI. Gore-Tex Active and Pro Shell are both rated to be 20,00mm, twice that of either NanoPro fabric. For almost all outdoor sports, I imagine that 10,000mm is a sufficient waterproof rating . I suppose under extreme circumstances a 20,000mm waterproof rating might be noticeable for example: mountaineering, alpine climbing, and even more likely, carrying a heavy expedition backpack.
NanoPro is constructed by a microporous, slightly wind permeable, coating of polyurethane(PU). NanoPro Membrain on the other hand is constructed of a microporous, slightly wind permeable, laminate of PU. Figure 1 below gives a pictorial side view of how a microporous PU jacket works. This being said, most laminates will be more durable than a coating. Think of a PU coating as paint being air-sprayed onto a wall while a PU laminate is more like wallpaper. How the PU is sprayed on or turned into a laminate is very much a trade secret.
|Structure and Properties of Microporous Polyurethane|
Gore-Tex Pro(newer generation) uses a multi-layer ePFTE sandwich to do the job without any PU backer that the older generation used.
|Gore-Tex Pro Diagram|
Gore-Tex Active uses a thinner ePTFE membrane while laminating the backer directly into the membrane. As mentioned in my Lanin Jacket review, a thinner ePFT membrane is more breathable than a thicker one.
Any jacket constructed of a laminate/membrane will be more durable than the sprayed on PU one. The difference among durability between any laminates/membranes has more to do with the construction of the jacket and the quality control of production.
Performance / Dollar Ratio (MSRP)
Let's take a look at the price difference between the two NanoPro fabrics. Marmot's entry level rain jacket is the PreCip jacket which starts at $100 and uses NanoPro. The cheapest Marmot jacket featuring NanoPro Membrain is the Essence jacket at $200. So for roughly twice the price, the breath-ability is roughly doubled and you get a more durable jacket. Marmot's Cheapest Gore-Tex Paclite jacket is the Minimalist Jacket at $200 while the cheapest Gore-Tex Active jacket is Nano AS at 285$. Marmot's cheapest Gore-Tex Pro jacket is the Speed Light jacket at $425.
Between Gore-Tex Pro and Active, I don't think the extra money is worth it for the Pro shell. The only reason to buy a Pro shell jackets is that they often use a larger denier face fabric, minimum 40, for extra abrasion resistance for sports like skiing or alpine climbing. I think the sweet spot for the performance/dollar ratio is around mid $200's. This would include any of the jackets using NanoPro Membrain fabric and the Nano AS jacket. I see no reason to buy a Gore-Tex Paclite jacket because NanoPro Membrain breathes better at the same price point.
Marmot's NanoPro Membrain laminate has added a lot of mid price options for weekend warriors and enthusiasts to the WBP jacket market. I expect we will continue to see more breakthroughs in the WPB materials in the coming years.We live in a golden era of material science and textile engineering.
I have noticed in real world applications that jackets using Nanopro Membrain wet out quicker than Gore-Tex active or pro shell. I feel that for individuals with heavy packs or out for than one day will find that the Gore-Tex products perform better. Those looking for a day hiking jacket will not notice this difference. I have an inclination that this has to do with how Marmot weaves their face-fabric. It would be interesting to know if Gore sells active shell or Pro shell in sheets of difference denier or if companies like Marmot and Patagonia are able to laminate their own face-fabrics to the membrane.
With Gore's introduction of Gore-Tex C-Knit, I feel that it's important that customers know that C-Knit fills the gap between Active shell and Pro Shell. It splits the difference between Active Shell being the lightest and Pro Shell being the most durable. Pro shell and active will be slightly more breathable than C-knit. The C-knit backer does improve breathability over the older traditional backers like like gore-performance and Paclite. I feel that most outdoor enthusiasts will find a nice performance and price point that it offers.