Call me a germaphobe if you want but I have always pre-washed every piece of fabric in sewing room. It is hard for me to tolerate the odor of the fabric and any estate sale I've been to. One instance of watching a very heavily rude persipiring individual and her friend on a very hot Texas heat day clinched it for me. She walked to a corner of certain fabrics and her friend and wiped their brows and pits. Management saw them then ushered them out, pulled the bolts of fabric. You could see the disgust on managements face. They have to return the merchandise to the manufacturer as damaged because of bodily fluids. ANother reason I prewash. I use lingerie bags by EVERCARE for 1 1/2yds or smaller. They look like pillowcases with hidden zippers. They are worth the $3 each. I also use them to wash bras and socks. Keeps them from being single with no mates.