DUNSTER - just an update I thought you might be interested in. I was reading about how Masterpiece thread by Superior Threads (for Alex Anderson) was modified from a 2 ply piecing thread to 3 ply because so many people were having breakage issues in their machines. On another forum a woman received a letter inquiring about Sigma and they stated it was the same thread but had a higher tensile strength. I have a feeling Sigma is a 3 ply and Metro is the 2 ply. Metro is shinier while Sigma is slightly less shiny ... sort of a sign that this is likely the difference.
Thought I would share what I learned!
