I realize that people used to put several different colors on a bobbin for "waste not, want not" but the bobbin was so poorly wound that it wasn't working properly in the machine. The black thread also seemes to be of a much coarser quality than the white underneath of it. I have wound some colors onto others to avoid wasting thread but made sure the bobbin wound properly. Had to cut off the black thread with my scissors b/c of the tangling while winding.