Fiber migration is what happens when either the stabilizer you use or the batting you use comes to the surface of the quilt during washes. I've never heard it called bearding but that's exactly what it looks like, lol. I used a water soluable stabilizer and had already rinsed it out but it seems that it's still coming to the surface after a few washes. I haven't added the batting yet so it can't be from the batting.