I used metallic thread on my Christmas panel last year. I even embroidered names on the socks in the panel. I used a needle especially made or metallic thread. The metallic needle was made by Schmetz an bought at Joann's. The eye of the needle is longer so that there is not as much stress on the thread. I used both the round and flat metallic and had no problems. I also used a little longer stitch (don't remember stitch length).