Once again, the fact that "breathability and breathability are different"

The term "waterproof and breathable material" is commonly used in this catalog and other Teton Bros. output.

Some of you may be thinking, "Huh? Isn't this supposed to be a waterproof, breathable material?" This is the term used to describe "Täsmä," the next-generation shell material that was released two years ago.

Indeed, the waterproof materials used in outer shells, with GORE-TEX at the forefront, are all labeled as "waterproof and breathable materials." They have a membrane with microscopic pores that "block water but allow water vapor to pass through," blocking rain and snow and allowing sweat vapor from inside the garment to escape to the outside. This is what "breathability" means.

The membrane of "Täsmä" also expels sweat and moisture through microscopic pores, but this is expressed as "breathability." The difference between the words "moisture permeability" and "breathability" is actually the difference in functionality itself.

"Breathability" means that water molecules in the form of water vapor can pass through, but not gas. Furthermore, the GORE-TEX membrane is made of a non-porous (hole-free) polyurethane film, so it allows moisture to pass through but does not allow air to pass through at all. On the other hand, "breathability" literally means that air can pass through. Try putting your mouth to both fabrics and blowing into them, and you'll be able to clearly see the difference.

Incidentally, the phenomenon of "breathability" is greatly influenced by various conditions, including temperature, humidity, and the difference in air pressure between the inside and outside of clothing. When your body temperature rises through exercise and you start to sweat, the temperature and water vapor pressure inside the clothing increases, causing water vapor to seep through the membrane toward the cooler outside air. This is the same mechanism by which air flows from hot to cold.

However, because the amount of breathability is limited, there is a weakness in that the rate at which you sweat exceeds the rate at which breathability can be achieved, or when the outside temperature is high and there is little temperature difference between the inside and outside of the clothing. For example, this is one reason why sweat does not dissipate as easily as you would expect when climbing a mountain on a humid day such as during the rainy season wearing waterproof and breathable rainwear.

In contrast, the Täsmä membrane begins to "breath" immediately from the moment you put it on, regardless of the conditions. This is the difference between "breathability" and "breathability." Of course, there is a limit to the amount of air that can pass through, but when comparing ventilation effects, it goes without saying which is more efficient: a waterproof "breathable" material or a waterproof "breathable" material.