Wool covers/overpants provide an optimal nappy climate, as they are particularly breathable and temperature-regulating. Wool feels warm in winter and cool in summer. It is antibacterial and neutralizes odors such as sweat and urine naturally due to the special structure of the wool fiber. Therefore, it does not need to be washed as often as PUL covers. Most of the time it is enough to just air your wool overpants. Only when they start to smell or have contacted with poo, it is time to wash and re-grease them.
Treating wool overpants with pure lanolin (adeps lanae anhydricus), or "grease," will make them leak-proof.
You can learn more about natural diapering with wool here!