I'm glad to see this thread as I am still so very hazy about thread and needles. One quilt teacher said to only use cotton thread as she had seen seams just pop when she used poly. What really has me concerned is that our local Bernina dealer said DO NOT use thread by Connecting Threads (there is a certain brand by them that I can't think of right now) as it has a coating on it and he can tell when he cleans the machines and charges $20 extra for scraping the coating off. Come to find out, this is exactly the thread that my quilting teacher uses. The Bernina dealer is very opinionated and thinks he knows best about a lot of things but- does he know best about this?