I can only speak from personal experience. I just completed an applique top that had 84 different fabrics, and I wanted to match fabric/thread. I had a really old spool of the exact color I needed. It was hard to work with. It kept breaking, and was hard to thread because it separated when cut. I did use it, but made sure I was using a "good" piece of thread. Hope it doesn't come back to haunt me. I did throw it out after I was done though!