I don't use fray block at all on quilting projects- I do use it on the edges of Aida cloth for cross stitch- when the cross stitch project will be framed- if it is to be sewn (like used for a pillow or even in a quilt) I zigzag the edges before working with it. as for what kind- what ever is available when I need it- since I mostly just zigzag and seldom have a need for it....it would be awfully difficult to sew through using it in a quilt & I don't think it washes out-so would create a stiff edge where ever it was put-