Breathability and Wicking: What’s the Difference?
Often interchangeable, these terms actually refer to two related, but different, capabilities. A garment’s breathability only refers to its resistance to air movement in and out of the weave or construction. A garment with a tighter weave or solid outershell will be less breathable because it won’t let air in or out. More breathable garments will feature tiny pores in the fabric that are larger than water vapor molecules (so these can get out) but much smaller than raindrops or snowflakes so outside moisture doesn’t get in easily. Basically, breathability is the ability for moisture to escape from under the garment, while keeping wind and water from getting in – meaning sweat evaporates, and you stay dry.
Wicking, on the other hand, can be serious science. Typically made from high-tech polyester, a wicking garment will feature a cross-section design in the fabric and a large surface area (instead of porous fiber like cotton with less surface area). These two elements combine to help the garment actually pick up moisture, carry it away from your body, and spread it on the surface of the material out so it evaporates quickly. Your sweat is carried away from your skin, and spread out for easy evaporation, keeping you dry.
Stay Away from Cotton, Look for Wicking and Breathability in the Cold
In colder weather, staying warm depends as much on staying dry as it does on wrapping up in multiple layers. This is especially true of the garments that are next to your skin. When you sweat, and the perspiration stays trapped on or next to your skin, it becomes nearly impossible to stay warm, even if you have on an extremely warm jacket. Moisture is the enemy of warmth – if your skin is wet, it’ll be more difficult to stay or get warm.
For these reasons, you always want to choose a breathable or wicking garment next to your skin and also in mid layers if you are wearing them. And you never want to wear a naturally absorbent material, like cotton. In fact, cotton will absorb 7% of its weight in water and will stay wet longer, while polyester will only absorb 0.4%, naturally drying faster and even extremely fast if it is a wicking polyester. This is why performance base layers will be made mostly if not entirely with polyester.
Combine Wicking and Breathability Based on Your Activities
If you are engaging in more rigorous activities, having a wicking base layer and breathable mid and outer layers will be important. For example, if you are going on a long Autumn hike, you may need a lighter weight jacket that is breathable so you can regulate your temperature, but you can also wear a lighter-weight base layer that helps wick away the sweat next to your skin. The combination of the two will help both warmth and dryness so you can overcome the cold.
For an activity in much colder weather, like skiing, you may want to combine a wicking base layer that’s thicker as well as a breathable mid layer so that when perspiration is wicked way, it is allowed to evaporate through both layers. For such a cold activity, it is likely you will have a water-repellent or waterproof outer layer, which will be less breathable. That’s why the wicking and breathability of base and mid layer are all the more important.