Not all wool batts are the same. Chances are, if yours is from one of the big batting manufacturers, it will not need to be pre-washed. However, you may have purchased yours from another source, such as a local mill. Some still have lanolin in them and need to be pre-washed. That's why it is important to check the instructions for YOUR batt, rather than rely on opinions of those of us who have not pre-washed OUR batts.