I've heard that a piece of tubular gauze used for bandaging fingers (available at drug stores) works well to slip over the spool of invisible thread to keep it coming off the spool without getting tangled.
I've used size .004 Sew Art International invisible thread, with a size 80/12 needle, and 50/3 cotton thread in the bobbin to stitch in the ditch without having any tension problems or breaking or tangled thread issues. I used it on my Viking machine with the vertical thread spool holder.
Last edited by Shoofly1; 11-07-2011 at 08:16 AM.