I do have to point out that for some outdoor pursuits breathability is more important than staying dry. The more aerobic the activity and the warmer the temperature the more likely you are to get wet from the inside out. Breathability is simply a function of moisture level of the air inside and out (or humidity vs. dew point to be precise.) The greater the gradient (High humidity on the inside, low on the outside) the more likely you are to move moisture. Some products, as you point out, allow for greater ease of movement of moisture from inside to outside. As a general rule, the more waterproof a product is (often expressed as millimeters of waterproofness) the less breathable it will be. Gore-Tex has definitely set the standard in many ways, but I don’t think I would always choose their products for every activity. For me, cycling and running are excellent examples where Gore-Tex (and other highly waterproof products) are appropriate 98% of the time. Granted Gore has many products, not just Gore-Tex, so there are Gore Windstopper garments (for example) that are more appropriate. Where “waterproof” is most effective is lower levels of activity and you are less likely to create more moisture on the inside than the garment can move per unit of time.

DWR is a “finish” or coating on a garment which causes the water molecules to bunch together forming beads due to the fact that water is a polar molecule. A DWR can be applied to just about any garment. Some microfiber garments are 100x more breathable than a waterproof garment, but repellent enough to keep you dry in all but a persistent downpour.

One last note, laundry detergents containing “surfactants” should never be used on garments which have a DWR finish. Surfactants are chemicals that are specifically designed to reduce surface tension of water in order to better and more easily have the soap molecules attach to dirt and grease. Unfortunately they then reduce the DWR finish effectiveness. Reduce surface tension reduces that “beading up” I spoke of earlier.

P.s. I was once a “Gore-Tex Certified Sales Technician” for what ever that is worth

And some people in the outdoor industry call DWR – durable water repellent (not resitstance).

Love the gear tips they are awesome!! I’ve been reading a lot lately about tarps…trying to take the, in my opinion, big step from traditional tents to tarps.