Before you drop that cash for a new shell...
Here's some interesting data from Phil Gibson (Army Materials Science Team) comparing one measure of breathability across several well-known fabrics as a function of relative humidity (constant humidity gradient). The details can be found here and here.
I couldn't resist the chance to plot another data set from McCullough et al. 2003, A comparison of standard methods for measuring water vapour permeability of fabrics (from their Table 1). They compared various methods of measuring breathability; the top four panels show measures of water vapor flux so bigger is better (the fourth, ASTM F2298, corresponds to Gibson's test at a higher humidity gradient and relative humidity); the last measures evaporative resistance so lower is better.
These data are consistent with the word on the street that eVent is king of the hill in terms of breathability (not sure where the newer Gore fabrics fit in here). Unfortunately, the use of eVent fabric seems to be more popular across the pond, with Rab and Montane making all sorts of nice shells (you can however buy this stuff through ProLiteGear). Wild Things also makes a nice shell (in the US no less!).
More relevant reading: Mar Verber's essay on Outdoor Clothing; Andy Kirkpatrick's article on Breathable waterproofs.
6 comments:
Certainly, looks like eVENT is better than GoreTex and others at breathability - of course, the waterproof/breathability tradeoff is the usual struggle.
I think that often what you need out of a shell is either waterproofness, or breathability - getting them both right is tricky, and possibly unnecessary in a single garment. My solution is to wear a softshell (very breathable, okay waterproofness) and carry a light but very waterproof shell if there's any chance of an epic or downpour (or both).
Brian, whatcha leaning towards?
Anyone want to hit New Rochelle this weekend? Most likely can't do Sunday...
Good point. All of the fabrics depicted are classified as "waterproof".
"The European Standard a fabric must meet to be classified as waterproof is a hydrostatic head rating of 1,500mm. Hydrostatic head is a fabric's resistance to water pressure equivalent to a column height of water. Whilst a hydrostatic head of 1,500mm will keep out heavy rain, it will not stand up to the increased pressure put on a fabric in general use and by rucksacks etc. On average, outerwear fabrics tend to have a hydrostatic head of 10,000mm and above."
-Source
Some numbers:
Gore-Tex Classic: 28 meters
Mountain Hardware Conduit: 15 meters
eVent: 30 meters
I'll update numbers as I find them.
I don't particularly need a shell, but if I find an eVent hardshell on sale, I'll probably snag it. Or I might just fold and get this Mountain Hardware shell (Gore-tex Paclite and XCR combo) that is on sale for super cheap.
I'm down with New Rochelle on Saturday. Please, for the love of God, can we leave early?
Another subtle point - waterproofness in a garment depends on not just the fabric, but the engineering and design: seams, zippers, shockcords, etc.
And yes, we hafta hafta leave early, in fact we can set a time - the Louiemobile leaves NYU station at 8:30 sharp, the hood station at 9...
Yup, a good amount of price variation seems to be due to things not related to the fabric, like taping and waterproof zippers and baffles. Must resist the temptation ...
I will be waiting at hood station at 9am sharp.
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