I do raw edge fusible applique and never had a problem. I use blanket stitch and embroidery thread. But as a safety measure I also use a product called Frey Block (i think it's called that) and it goes on clear and stays soft and pliable. It's not the same thing called Fray Check that we used to use when making clothes. I did find out that I needed to wash the sizing out of my fabric before I fused it.