Wool keeps sheep dry. Why? Wool’s structure produces an elegant combination of
- water repellence,
- breathability and
- moisture absorbency.
Wool Fabric Is Water Repellent
At a microscopic level wool consists of a series of overlapping scales (called cuticles) which have a tendency to repel water droplets. This structure, in combination with a thin coating of lanolin (an oil secreted from the sheep’s skin) causes water to run off the fibers. (The duck’s back effect is also a sheep’s back effect.) Natural water repulsion makes wool a good candidate for a diaper cover or puddle pad.
Wool Fabric Is Breathable
But there’s more. Many artificial fibers also repel water, but that alone does not make them a good choice for a diaper cover–a plastic bag would fill this condition. It is important that the fabric also be able to breathe, or the temperature next to baby’s skin will rise. Breathability (and hence reduced skin temperature) is an important factor in preventing diaper rash.
When a woven wool fabric is boiled, the fibers become entangled and they form a lofty mesh with many tiny air pockets. This process is called fulling. Fulled wool is a highly water-resistant, breathable fabric.
Individual Wool Fibers Absorb Moisture
There’s (yet) more. There are artificial fibers that both repel water and breathe–Goretex is one such fabric. The third important property of wool is that it also has the ability to absorb moisture at a microscopic level.
Beneath the water-repellent outer cuticle of the wool fiber is a highly porous core. The voids in this core can store minuscule water droplets–up to 30% by weight of the fiber itself–so that wool is able to both absorb and transmit moisture simultaneously. This is a very elegant, balanced mechanism, and there is no artificial fiber that can do this.
Wool – the Best Choice for Diaper Covers
This threefold combination of water-repellence, breathability and moisture absorbency make wool unparalleled as a choice for diaper covers.
It is also worth noting that even if an artificial fiber could be manufactured that exactly duplicated the properties of wool, the artificial fiber would still be a less desirable choice. Without exception, attempts to mimic nature are highly energy and resource-intensive, even if they achieve their goal.
Simple wool keeps sheep dry. It will keep your baby dry, too.
Text and images copyright © 2001 – 2017 Marc Pehkonen. All rights reserved.