If I am making a quilt top, I just use the quilting thread that Wal-Mart sells (I'm a cheap date). If I am sewing clothing, I use just the dual-duty. I believe the brand is Coats. I am afraid to say this for fear that it will turn my luck, but I have not had any trouble. I have a Elna, White, Brother, Paff, and have had a Singer and a Sears. Years and years ago there was some kind of spun poly thread that was horrible. I do keep scraps near my machine and sew samples to get the right needle, right tension, etc. Once I was using a metalic thread, ran out, changed to the next spool and could not keep it from breaking. I metioned this at my quilting store and the owner told me that the manufactorers have told her that this sometimes happens because of a problem with the thread itself. Also, on a recent quilting show --- I think Sewing with Martha -- a man who is vice-president, president (???) of Baby Lock demoed some fancy sewing which required satin stiches ---- he was using something from a bottle to drop on the spool of thread. He said this caused the thread to feed through all the twists and turns smoothly. Haven't we come a long way from just a spool of thread????????