The reason I heard black thread causes more problems and may break easier than other threads is that it takes a lot of chemicals and dye to get a black color. It apparently is the hardest color to make. Anyway, I try and use my bobbins up and to wind just the number I will need to begin a project with (OK, a lot of times I don't guess right) I have one friend who when she comes to quilt with me will use one of my machines and she just keeps putting in the bobbin with the least amount of thread on it to use it up. I like when she comes! I have been mostly using 50 weight thread for my piecing but I also check the thread when using up those bobbins as I don't want to use embroidery bobbin thread or thicker thread either way. I do a lot of scrappy quilts and usually use a neutral color to piece so most blend in pretty well anyway. When I do unwind bobbins, sometimes I just stick them in a jar and let them bounce around as I pull it off or I just use them as my exercise program for the day chasing those rolling bobbins around the floor.