I've used monofilament for quilting without too many problems. But, once I got the bright idea to use it in the bobbin. Ended up with the thread wrapped around the shaft of the bobbin winder and caught down in the machine. I spent a couple of hours clipping and pulling little plastic threads out of it. THEN somebody told me you have to wind it by hand to use in the bobbin because it stretches. Doesn't matter, I don't think I want to try it in the bobbin ever again.