On one of the quilting shows they did a technique where you hand or machine quilt through just the top fabric and a layer of batting. Then you cut away the batting from the areas where you don't want the special effect and then finish the quilting by making the sandwhich with the top, regular batting and a back. That makes certain areas really stand out because they have the extra batting. If you don't want to quilt with quilting thread over the same area twice you use thread that melts away when it gets wet for the first quilting.