Maybe??
I buy the big bolts too and have been working my way through a white cotton 90 inch by 40 yards and so far it's been great. I keep it in the finished basement because that's where the layout tables are where I baste.
Today I unrolled it to cut a piece and there are stains on it that I think are mildew. I have no idea where it came from and the bolt hasn't gotten wet. It doesn't smell. The stains were on an inner layer. I attached a photo.
I'd like to get rid of the stain and still be able to use the batting. The cost of the roll has gone up $100 since I bought it.