When I made a t shirt quilt I had to stabilize the knit with a backing of light-weight interfacing first to stop it from growing under the needle and stretching while quilting it. I just ironed it on with an up and down motion so it would not stretch and then I made the quilt with no problems at all. I will say this, I will never make another one. It came out wonderful, but, I did not enjoy the process at all. Make sure you use a denim needle to quilt it with, it becomes a little thick to needle through.