I'm pretty sure my Mountain Mist Blue Ribbon 100% cotton batting is 100% cotton.
With the WnN, it may be the scrim that is not cotton. WnN is needlepunched through scrim to give it stability.
I like my MMBR but would not recommend it for hand quilting. It also needs to be quilted no further apart than 2 inches. It is not needlepunched and has no scrim.