I know from years past that poly does bearding but I haven't noticed that on cotton. Hobbs makes an 80/20 black so that would be the one I would try if I needed to. I used white Quilters Dream Request on a dark flannel and wool with no problems. I understand that if you use the smoother side of batting on top you won't have bearding but no experience personally. Do you have a piece of your regular batting and some of your dark fabric to make a sample?