@kake I don’t know if it varies with the same fabric. I’ve used the double couched hem on three necklines of three different jersey fabrics. I believe the width might be the important factor because it curls on the ones that are thinner more than the one that is wider, I think. The one I showed is wider than the other two. Also the tightness of the curve makes it curl more. I’m not sure how the stretchiness impacts it.