Thank you for your reply.....I am going to be using different fabrics and I am mainly going to use the interfacing on some Tshirt material - - I want to do what I can to keep these blocks from stretching. I have purchased Lightweight and medium weight interfacing because I was not sure which would be best. Maybe the lightweight will work for my quilt Good point about the larger quilt stitching on the knits.. I will keep that in mind