Starch, or use sizing Before you cut your strips. It sounds like you are distorting them after cutting. And to help you stitch your 1/4" seams for a while try drawing the 1/4" line on the strip then sew right along the outside edge of the line. After some time you will find it automatically and won't have to draw it anymore. Although, after 49 years of sewing occasionally I still draw that line. You need to sew along side it, not right on the line- that allows for opening/pressing the seam.