It can be difficult to know when you should lanolize wool and how to do it, so I’ve decided to share some great information on the topic by my knowledgable friend, PovertyJane. She has plenty of cloth diapering experience, having six children, and also lots of sewing knowledge from her eight years of sewing creations.
Squeeze ¼” to ½” of tube lanolin or a squeeze of liquid lanolin (found online or in health food shops) into a cup of hot water, in a jar with a lid. Add a few drops of wool wash, cap the jar, and shake vigorously to emulsify. Let the mixture cool slightly. Pour it over the item(s) that are soaking inside out in your sink or basin, aiming at the crotch and gussets. Squeeze the items a few times to distribute the lanolin mixture. Soak for 15 minutes or so, and then dry as directed above.
When using liquid lanolin, you may use warm water to emulsify. Solid lanolin such as Lansinoh is more effective than liquid lanolin or lanolin sprays. Start with ¼ inch and see if you need more. If you overdo the lanolin, the cover will feel greasy. That is actually ok if you don’t mind how that feels, and you wool will perform very well with the extra lanolin.Also, turning the wool inside out halfway through is a good idea. Laying flat on a sweater drying rack is great so they don’t stretch out yet air can circulate.
How often is “periodically”? How often should I wash the wool covers or lanolize them? It varies a lot! I’ve heard some say they almost never wash their Aristocrat; others wash them every other week. It seems that washing once every 3-4 weeks or so is common. Some relanolize once a month, others relanolize at every washing. It’s very personal. When the cover has a foul odor when it’s dry, it’s time to wash it. Or when the dampness comes right through the cover, it’s time to lanolize (or possibly it’s time to add more cotton inside, such as double diapering or adding a doubler or two).
Wool is not waterproof. Just air out the wool. Do not expect wool to be waterproof like synthetics. But it is very breathable, which is cool and wonderful. It is the lanonlin on the wool that is water resistant, and the wool is actually absorbent. The wool is supposed to get damp when the cotton inside is sopping. That’s ok! Just air it out and use it again.
Defining when washing or lanolizing is needed varies tremendously. Try putting some water on the cover from the sink. If the water soaks right in, then it’s time to lanolize the cover. If the water beads up a bit, it doesn’t need more lanolin, but you might need to use more cotton to get more absorbency. Do what works for you.