I've hemmed countless prom/bridesmaid dresses since I hung out my shingle, but today's was one of the worst. Just when I think I've mastered every type of fabric possible, they throw something different at me. Today's was a chiffon-weight knit. I always use the trimmed-off part to practice on the fabric before doing the dress, and I tried 2 different rolled-hem feet, and 2 methods with the regular foot before I could get a decent hem on it. Ultimately had to fold once and stitch, then fold again and stitch. Second dress I had on my table today was a satin. I was thrilled to get a nice "normal" fabric, until I got that one under the needle and realized it also was a knit as it did it's best to stretch instead of gliding smoothly over the feed dogs.