Wool diaper soakers, or pull-on covers, can be used over cotton flat or prefold diapers, instead of traditional "plastic pants" or PUL diaper covers. Wool is very absorbent, making it perfect for nighttime use. It's also a breathable fiber, even when damp, which allows air to circulate and dry the diaper out quickly.
Alpine Wool (100% wool roving) - Bay Leaf, by Lion Brand Yarn
Alpine Wool (100% wool roving) - Vanilla, by Lion Brand Yarn
The pattern was inspired by Woollywumpkins Easy Soaker Pattern. This pattern is available for free on Ravelry and is currently a free download on the Woollywumpkins website. However, it's written in British crochet, and the instructions call for a crocheted body with knitted ribbing around the waist and legs. The wool diaper soaker I made was created entirely with crochet, and has several changes to the original pattern.
After use, the wool diaper should be air-dried in a well-ventilated area. Poop should be washed off (using a mild detergent) and then air-dried. Every few weeks, the cover should be washed with a wool-friendly detergent (like Marseille soap) that won't strip the natural greases from the wool. A small amount of vinegar may be used in the rinse cycle to soften the wool. Occasionally, the diaper should be treated with lanolin to treat the wool and improve absorbency.