I have used Hobbs Wool and Dream Wool battings many times and have always machine washed/dried them- they come out fluffy, light, soft- wonderful! I do not know what (brand) of wool batting you have used- if it is some other brand I would follow it's instructions, or take a chance (what I would probably do) and try drying it on low heat in your dryer- or, if you have any of it left put together a small (quilt sandwich) with the left over, zigzag the edges- do a bit of quilting across it to hold it and try washing/drying it. see how it comes out-