You still stitch around the appliqué when using fusible like heat n bond, it washes away when laundered. I've done them both ways, both ways work well & hold up. I stitch my appliqués with a small blanket stitch, have not had any problems with them fraying or coming off any of the dozens of kids quilts I've made. The interfacing method seems to add a little more bulk to the piece that you don't get with the fusible that wash away.