I have had a lot of people asking me about wool lately and figured I should share some of the things I have learned.
When selecting a cover, remember not all wool is equal. When picking wool to use as diaper covers it is important to get something that is nice and dense (this can be a wool interlock or a knit). If you are planning to use it overnight (or on long car rides) then having a double layer in the wet zone is also a great idea. I have used single layer wool longies overnight with no issues, but they were a high quality interlock. Single layer wool is fine, but is better suited for day use. Knit covers can be beautiful, but they need to be very tightly knit, out of good quality wool, to work. If you have something that is a looser knit, don't expect it to work over night. Use it for day wear and change the diaper often.
Lanolin makes your wool work. It doesn't matter how nice a cover you have, if it isn't well lanolised it will not work the way you need it to. There are 101 different ways to lanolise and a lot of different products. Your goals when lanolising are to get a nice even layer over the whole wool piece, to get a little extra lanolin in the wet zone and to avoid staining your wool. Some wool covers are hard to stain (such as the Woollybottom hybrid covers made from old sweaters) some will show blotches of lanolin a lot more easily (bright coloured wool interlock).
Get your wool clean. You do not want to lanolise wool that is covered in stains or that is soaked with pee and full of urine salts. Most wool needs to be hand washed, so getting it clean can take a bit of work. You can wash in a number of different ways, with baby soap, dish detergent (like original blue dawn or 7th generation) or a gentle soap like Ecover. There are also special wool wash bars you can use to gently scrub stained areas. Wool does much better in room temperature to slightly warm water. Too hot and you risk your wool felting. It is also better to change the temperature of wool slowly. Some wool is sensitive to being "shocked". Some wool is hardy enough you can wash it on a"wool" or "gentle" cycle in your washing machine. Once your wool is clean, it is a good idea to rince it well to get any soap residue out, especially if you have used a dish detergent. Gently squeeze the water out, without being too rough on the wool.
Once your wool is clean it is time to condition it. The best way to get a nice even layer of lanolin over your whole cover is to do a wet soak. For a wet soak you need to have some very hot water to dissolve the lanolin. I take a mason jar with a cup of water in it and heat it in the microwave for 2 minutes. Once you have hot (almost boiling) water drop a hunk of lanolin (there are many brands) into the jar. I like to use a fair size chunk (Hershey kiss size or bigger) for each piece of wool I am going to soak (I only do 2 or 3 pieces at a time). Some people say a pea sized amount, but I dont find that to be quite enough. The more you use though, the more risk there is that you will get lanolin clumps and stains. Let the lanolin dissolve in the hot water, it will look clear and kind of oily. Now the fun part... take your favourite baby wash or liquid wool wash (like Eucalan) and put a big squirt into the mason jar. Give it a swirl or a stir and watch it magically turn white :) Fill up your sink (or bucket) with warm water (not hot, but warm enough that it wont cool the lanolin too quickly). Add the mason jar of lanolin mixture to the warm water and mix it around with your hands. You can also add a nice smelling essential oil at this point if you are using unscented lanolin. Now, turn your wool inside out and add it to the lanolin bath. Weigh it down with bowls or plates if need be and let it soak from 15 minutes to overnight. Once the soak is finished, squeeze the water out, roll in a towel and squeeze it to get as much water out as possible. Lay flat to dry.
Once your wool is dry you can use it, or you can do one further step to make sure it is really bullet proof. I like to add some lanolin to the wet zone on the inside of my wool piece. There are different brands of spray lanolin, that can just be sprayed lightly all over the crotch area. You can also use a solid lanolin and do a method called "dry lanolising". Take the lanolin and soften it in the warmth of your hands and spread it out over your palms. Very gently pat the wet zone until there is a nice even layer all over, then massage it into the wool.
Once your wool is squeeky clean and well lanolised you can use it for a while. If it gets damp with pee, just turn it inside out an allow to air dry. The lanolin reacts with the pee and turns it to salts. After it is dry there will be no urine smell at all. Eventually your wool will either get dirty from wear (like a toddler sitting in a mud puddle or dumping spaghetti on their lap) or it will start to have an odour after it is dry. Then it is time to wash again.