Coming from the view of a frame quilter----even muslin adds bulk. The problem is the intersections where the blocks are joined together. It is quite thick and can mess with the timing if hit just right. I did one for a friend and had to be very careful not to quilt right over those intersections. She used quilting cottons on muslin, batting and backing. I did not like how it looked as the intersections were a bit "sticky upity"...like a tiny mountain peak.