I'm fairly new around these parts, but I am guessing that you are talking about making diaper covers??
If so... I have made some for my daughter with recycled sweaters that were not 100% wool and they seem to work just fine. I made them with 2 layers and I haven't had any leaks or wicking. And the sweaters that I have used had as little as 70% wool mixed with some angora and nylon and the like.
If you weren't talking about diaper covers... then I have no idea!!

-Karylann