By Mike Harostock, Andy Rampp, Adam Scott and Rob Shaul
“You begin a brisk uphill hike, in 35-degree weather and steady rain. You are wearing a “waterproof, breathable” jacket and carrying a 45# ruck or pack. You begin to heat up, but must continue to wear the jacket or risk getting soaked through by the rain. If your jacket is 100% breathable, your base layers can vent and remove the sweat, if not, your base layers get soaked. After 60 minutes the temperature has dropped to 25 degrees, and for safety reasons, you have to stop moving. If your base layer is soaked with sweat, you begin to freeze.”
This scenario describes the mission-direct utility of a waterproof, breathable jacket.
Different fabric manufacturers deploy different fabric technologies to achieve fabric breathability. For this Mini-Study, we were particularly interested in the coating, and membrane. Gore company first developed breathable fabrics, which is now ubiquitous “Gore-Tex.”
Gore, and others, have demonstrated the breathability of these products in laboratory settings and infomercials such as this. However, we could not find a functional, mission-direct Mini-Study or test of breathability. Which led us to this Mini-Study.
Five Jackets were tested:
Jacket Cost Fabric
Colman Rain Jacket $15 PVC (We wanted to compare to a non-breathable jacket)
Marmot PreCip $100 NanoPro Coating (Marmot’s proprietary coating)
Marmot Minimalist $200 Gore Paclite
Marmot Nano $300 Gore Active Shell
Marmot Alpinist $600 Gore Pro-Shell
With the exception of the Colman rain jacket which we purchased at a local sporting goods store, we chose Marmot brand for the other jackets assuming sizing and fit would be consistent. All jackets were size large.
Our Mini-Study results were pretty decisive. We found that a breathable jacket can help decrease sweat retention by as much as 500% when compared to non-breathable jackets. We also found that breathability alone accounted for less than 9% of jacket price differences. In fact we found the cheapest breathable jacket, the Marmot Precip ($100), was actually more breathable than all three of the Gore-Tex models ($200, $290 and $600).
If you are interested in learning more you can read the full report: Mini-Study White Paper Link. Or, check out the Summary Below…
The purpose of this Mini-Study was the assess jacket breathability and cost in order to determine if Gore-Tex is worth the extra price.
All subjects (n=3) were actively training military or mountain athletes. Mini-Study subjects averaged a height of 70.3 +/- 2.3 in, weight of 188.7 +/- 31.7 lbs and age of 30.3 +/- 3.1 years.
This Mini-Study focused solely on breathability, not waterproofness, durability or windproofness. Five jackets were selected to represent five popular price-points (Coleman PVC-$15, Marmot Precip-$100, Marmot Minimalist-$200, Marmot Nano-$300 and Marmot Alpinist-$600), utilizing five prominent types of waterproof technology (PVC, fabric coating, and fabric membranes like GORE-TEX).
Each athlete completed six total trials over 2 days. Trials consisted of a 30-minute brisk treadmill walk at 3.0 mph and a 15% incline, with a 50 lb ruck. The first trial was a control – no jacket was worn, but the baselayer was weighed before and after. Athletes’ hydration was controlled and tested before and between trials.
Jacket trials were completed with the jackets fully zipped up, including any pit zips, and hoods on. We were interested in testing the breathability of the jacket, not the effectiveness of its zippers venting design.
Before and after every trial researchers collected Jacket weights, Base Layer (long sleeve top) weights and HR Monitor weights, plus a Total Weight which consisted of the athlete and all their equipment. Each athlete completed an in
itial baseline “control” trial without a jacket. After the control was established the athletes completed five more trials, one with each of the jackets. Jacket order was randomly assigned and athletes were allowed approximately 30 minutes between trials to rest, recover and rehydrate.
Mini-Study controls were balanced against the MTI mission direct requirements. Controls were used primarily to standardize the trials across the Mini-Study participants and trials. Control measures were used for the athletes, efforts, jackets, base layers, clothing, packs, hydration, temperature and humidity.
1-4. Results & Discussion
After a preliminary statistical analysis MTI researchers narrowed the focus solely to changes in Base Layer weight. The research assumption was that the more the athlete sweated, the heavier the base layer would become during the post-trial measurement, and thus, the less breathable the jacket.
The Mini-Study produced a few significant findings. First, breathable fabrics represent a significant improvement over non-breathable fabrics. On average the 0.20mm PVC jacket (non-breathable material) increased the athlete’s base layer sweat by about 6.0 oz (approximately half a can of soda or 267% over baseline). By comparison, the two most breathable jackets, the Precip and the Nano, only increased the athlete’s base layer sweat retention by 85% and 79%, respectively. This amounts to between 1.8 oz and 1.6 oz of sweat.
Second, HR (effort) and Baseline Sweat Rate had a significant impact on a jacket’s breathability. HR alone could be used to predict base layer sweat to about 60% accuracy and Baseline Sweat Rate was accurate to about 62%. Jackets also have a significantly higher impact on lighter sweaters. On average, all five jackets produced a 400% increase in sweat in the low sweat athlete. In the high sweat athlete the overall average increase was only about 127%. The Graph below shows the average sweat retained in the athlete’s base layer when wearing a jacket.
GRAPH: Ounces of Sweat Retained in Base Layer (ounces)
Lastly, jacket weights varied significantly. The lightest jacket, the Precip, weighed approximately 11.5 ounces. The heaviest jacket, the Alpinist , weighed almost eight ounces more, 19.4 ounces. A quick comparison of jacket weight to breathability revealed the Mini-Study’s only significant correlation – As jacket weight increased breathability decreased.
1-5. Conclusion, Recommendations, Next Steps
1. Breathable fabrics work.
Breathable jackets can help decrease sweat by as much as 500% when compared to non-breathable jackets.
2. The more someone sweats the less effect “breathability” has on base layer sweat.
This was evident in a few places in theMini-Study’s data. First, our heavier sweaters were less effected by the jackets. Second the harder an athlete worked the less effective the breathability was at removing base layer sweat. And lastly, anecdotally, the heavier the jacket, the more the athlete sweated and the more sweat was retained in the base layer.
3. Jacket pricing is not related to breathability.
Jacket pricing is a product of, among other things, durability, fit, features, fabric, waterproofness, windproofness and, finally, breathability. Our Mini-Study showed almost no relationship between price and breathability. In fact, based on this Mini-Study, less than 9% of the jacket’s cost can be accounted for by its breathability.
If an athlete’s only concern is finding a cost-effective, waterproof, breathable jacket then, based on this Mini-Study’s findings, Gore-Tex does not appear to be worth the price. This Mini-Study showed that breathable coatings (like the NanoPro) offer superior breathability at a much lower cost.
Three are identified:
Gore-Tex was the first and is best known, but many others exist including Polartech NeoShell eVent and membranes from Toray, etc.
Many major clothing manufacturers have proprietary coatings including Marmot, Patagonia, The North Face, Mountain Hardware, Outdoor Research, etc. A side-by-side comparison could prove enlightening.
This Mini-Study found a jacket’s weight, and thickness affected waterproof breathability. Marmot’s Alpinist Jacket is their top of the line piece – and most durable. A Mission-Direct study of durability would assist mountain and tactical athletes of finding the sweet spot in breathability, durability and cost for jacket purchasing decisions.
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