I use a simple test to measure a garments breathability; I hold a single-layer section (no underlying pockets for example) of the garment up to my mouth and try to breathe in or out. My breath is essentially 100% hot,humid air at some overpressure.
If ’10’ is unrestricted breathing and ‘0’ is no air flow whatsoever, I get the following subjective results..
– Regular old fleece:10; I can breathe normally through it.
– Junko Tabei brand eVENT jacket:4
– Teva eVENT jacket:3 (little more difficult)
– Columbia 2.5 layer Goretex:2
– ECWCS 3 layer Goretex:1 (almost nothing)
– The North Face DIAD:0(!)
– REI Elements PU jacket:0
I was very surprised and disapointed at the results for the DIAD, given its reputation for breathability. Luckily it has pit zips. Is there some characteristic of the DIAD 2.5 DT HyVent which makes it able to pass water vapor but unable to pass any of my breath no matter how hard I pressurize it? It seems that the 2.5 DT HyVent is no better than a $1 plastic raincoat. What’s up?
Is my test representative of the transmissability of water vapor for the garment? I am especially hopeful to hear from one of our posters or staff with professional fabrics knowledge.

