Fabrics moisture absorbing vs moisture wicking
Posted on 04 April 2017
What’s the difference between fabric that’s moisture absorbing and fabric that’s moisture wicking? How do you wear clothing made from the right fabric for your activity?
Recently, during a chat with a friend, we were asked why we have chosen bamboo viscose, a moisture absorbing fabric, rather than a moisture wicking fabric for our men's undershirts. They assumed that a wicking fabric would move sweat away from the body quickly and hence be a better choice. That's the case when you don't mind your sweat showing up on your next layer, but it's a mistake when you want to avoid sweat showing through on a shirt. In this article, we'll explain the difference between absorbing and wicking and how you can make the right choices for your activity.
Moisture absorbing fabrics
Moisture absorbing materials have fibres designed to absorb and capture sweat.
The most common absorbent fibre used is cotton. More recently fabrics have been designed that are more absorbent, like modal, micro-modal, Tencel®, and other viscose-based fibres. All of these are made out of the same base material - plant cellulose - which loves water. Water (or your sweat) gets absorbed into tiny gaps called micropores inside the fibre.
Pictures of cellulose-based fibres under an electron scanning microscope. The dark areas show water absorbed into the structure of the fibre. Picture Lenzing Fibres
Moisture absorbing fabrics are especially beneficial for those people who want to avoid any sweat marks showing on outer clothing as they trap sweat before it reaches your outer clothing. Absorbing fabrics will, therefore, minimise sweat-through.
For example, an undershirt (made from viscose or cotton), worn under a shirt, will trap sweat before it reaches the shirt. Sweat is held inside the fabric of the undershirt so you won't feel wet on your skin and your shirt won't show any sweat marks. That is why moisture absorbing fabrics are best for undershirts.
Moisture wicking fabrics
Moisture wicking fabrics include synthetic fibres like polyester and nylon (or fabric which has been treated with a solution that prevents water absorption).
Polyester and Nylon are made from materials which are similar to plastic and, because of their particular chemistry, they are water resistant. That means instead of the water going inside the fibre it sits on the surface of the fibre in droplets and moves around the fabric by running along the weave. Eventually, the water droplets reach the outside of the fabric where, if exposed to the air, they will evaporate.
Picture of polyester fibre (left) and Tencel viscose fibre (right) under a scanning electron microscope in a moisture rich atmosphere. Water droplets are visible on the surface of the polyester fibre because it is water resistant fibre best suited for wicking. On the Tencel viscose fibre the water has been absorbed into the fibre itself. Picture Lenzing Fibres
A wicking material will not absorb moisture meaning it will dry faster in heavy sweating conditions. Perfect for wearing as a single layer, during sporting activities, when the sweat can evaporate directly into the air. It can, however, be a problem when being worn underneath another layer, such as a shirt. The wicking layer would quickly deposit sweat straight onto your shirt making visible sweat marks, which you (probably) don't want.
Wicking materials will tend to cool the body a bit more quickly than moisture absorbing materials, and so they are best worn in situations where it is important for sweat to leave the body quickly. I wear a moisture wicking fabric for my sweaty yoga class, for example.