I use monofilament thread as the top thread on most of the quilts that I quilt on my Bernina. I sew 4 or 5 very close stitches at the beginning and the end, then I hand knot the ends and bury them. So far, I haven't had any quilting to come unsewn. I use a polyester thread and have had no melting. My only problem is threading the needle. I don't see well and the thread is difficult for me to see. I use a "cheater" needle for burying the threads.