It is a huge pain in the ass to clean. I bought ten pounds of white merino fleece. It's pretty clean, not a lot of vegetable matter but it's SUPER greasy! The normal "clean the fleece in the washer" doesn't work for this stuff. I'm having to put it pots of soapy water on the stove to get the water hot enough to break the grease down. Then, the wool is so fine that what little VM there is in the clean wool, it wants to stay put. Ugghh.....! However, when it's clean, it's beautiful. Let's hope I can spin it up into something nice.
PS: If anyone has a more efficient way to break down the grease in fine wool fleece, I'd love to know your secret.