Quilting with Metallic Thread

When I took my machine quilting course, as part of the course I tried various threads and vaious needles for quilting. In the picture below of one of my practice pieses, you can see that I was able to quilt my name and other doodlings in purple metallic thread. 

I intended to use the same thread to quilt my purple Christmas tree skirt. And since I had been successful in the sample above, I didn't anticipate any problems. I was wrong. The thread broke repeatedly. I tried different needles, adjusted the tension, reduced the speed on my sewing machine and changed the bobbin thread to polyester (I had been using Aurifil cotton 50 weight). I even tried sewing with two threads; one metallic and one cotton. That was messy. Nothing worked continuously. As a last resort, I wound the metallic thread onto the bobbin and used polyester thread on the top and stitched with the quilt facedown. Of course, this necessitated unpinning all of my pin-basting and moving the pins to the back side of the quilt. But I was finally successful. 

I have numerous spools of purple thread, in both cotton and polyester, so I could have easily switched to a non-metallic. But I had the metallic purple and I wanted to use it. It adds a little bling to the tree skirt. Next time, I'll just know from the start to use the metallic in the bobbin. However, I'm still puzzled as to why I was able to use it successfully previously. <shrug>

Up next: binding. Next problem: how to bind that tiny little circle in the middle of the tree skirt...