Originally Posted by
bearisgray
When I took classes at Stretch and Sew - the method was:
Use a longer stitch - stretch the fabric as one sews it - and then when the fabric is relaxed, there is some "stretch" in it.
Practice on some scraps. I think we used about 6-8 stitches to the inch when sewing sweatshirt fabric.
For added durability, sew a second seam about 1/16 inch away from the first seam - stretching the fabric again while sewing.
This is how I learned to do it too. Also, you can now find stretchy knit serger thread. It works great for kids knit wear, and you can use it on your straight stitch machine. And, as Karen mentioned, a ball point or knit needle is necessary.