Wind Proof Fabrics?

[oldgringo]

My questions are several...is heavier weight fabric (1.9 rs) more wind proof than lighter weights? Does calendering make a difference? What about dwr? Finally, what is the relationship of wind resistance to breathability...they're not the same thing... or are they?

[WV]

I can only provide a partial, unauthenticated answer, just short of SWAG. On breathability, one issue is said to be how water vapor, not just air, passes through the fabric, and that's complicated by the fact that it's usually encountering a cooler layer of air as it does so. There are fabrics that purport to be good at dealing with those conditions, such as Momentum90, Pertex Quantum, and Pertex Microlight. They do so by having a smooth side and a fuzzy side (produced by a special weave and/or calendering?). The smooth side is the inside. As some of the water vapor condenses on the fabric fibers, it is moved to the outside by capillary action, where it evaporates faster because of the greater surface area of the fuzzy side fibers. That explanation has been gleaned from reading several occasionally vague and sometimes contradictory web pages, so don't take it as gospel. However, it seems to agree with my experience using Pertex Microlight for the upper walls of my winter hammock tent. The lower walls are silnylon (down to a tiny footprint, just room for pack and feet), and the tent does a good job of blocking breezes and keeping internal temperature quite a bit higher than outside. In temps around zero there is more frost on the outside of the upper walls than the inside. Someday I'm going to use more of my Microlight to make a wind shirt (pattern needed - anybody?) and a quilt or insulated hammock. It's a nice feeling fabric.
I don't know if this speaks to the issues you have, Dave. I'd like to hear more info from others. Thanks for posting this.

[gmcttr]

From my limited experience...if you hold the fabric tight to your mouth...
1.1 is easy to blow air through
1.9 is harder to blow air through
1.1/1.9 calendered is difficult to blow any air through

While laying in a hammock made of these materials in an intermittent breeze, I can feel the difference on my back.

Although increased air passage will greatly effect the transfer of water vapor, even the calendered nylon is sold as "breathable" as are many "windproof/waterproof" fabrics.

[warbonnetguy]

i've not done scientific tests nor read any, but generally i'd say the higher the threadcount the more wind-resistent/less breathable the fabric will be. (30d is a higher TC than 70d usually so the 30d should be more wind resistent) hot calendaring also makes the fabric more wind resistent/less breathable.

if i were gonna make a sock or something enclosed and wanted to avoid condensation buildup from breathing etc, it would be un-calendared fabric.

i'm not certain, but it doesn't seem like dwr effects breathability much, the calendaring and tc definately do.

[Ramblinrev]

i've not done scientific tests nor read any, but generally i'd say the higher the threadcount the more wind-resistent/less breathable the fabric will be. (30d is a higher TC than 70d usually so the 30d should be more wind resistent) hot calendaring also makes the fabric more wind resistent/less breathable.

When you talk about denair ratings and thread count you also need to take into consideration the weave pattern. Given the same weave pattern I think you are correct in the assessment. However, if you are comparing two different weave patterns, eg. ripstop and taffeta, I'm not sure the same relationship would hold. No solid science there, just my own experience with fabric.

[warbonnetguy]

i don't know, i've not compared identical fabric (tc and denier) where the only difference was the weave so i can't say, would be interesting to see there is a difference.