I noticed curling on my Connecting Threads thread when it's about 3/4 used from the spool. I didn't know if it would cause any issues so I put that spool aside and now only use it when I'm basting my hexagons for EPP. I am going to check out Bob's YouTube posts. I do love superior threads and will probably stick with them from now on. Hopefully they will have another special where the Try Me threads are 50% off.