I don't think the Amish needed to use black batting in part because they were hand quilting. Bearding is more likely with machine quilting for a couple of reasons. (1) The needles that machines require are much larger than hand quilting needles, resulting in bigger holes. (2) There tend to be many more stitches per inch of quilting with machine quilting, making many more holes along a line of stitching.

Also, the way the quilts are washed is considerably different from the way most of us wash quilts; the Amish don't use electric washing machines. This means there is a lot less mechanical agitation and rubbing of quilt against quilt.

I think these three factors combine to reduce the likelihood of bearding in any quilt.

Legacy makes a black batting which is 70% cotton and 30% polyester. I have it but have not used it yet.

I ordered a Hobbs 80/20 black batt from Quilted Memories LLC on their 50% off sale and it should be delivered tomorrow. Thanks for everyone's advice. With black I won't need to worry about bearding or hazing. I have put too much work and money into this quilt to run a risk.