Any color is fine to use. I wonder if Sulky 12 weight is too thick? I've used that for hand embroidery and love it. It's equal to three strands of embroidery floss. You can get small spools of it inexpensively so it shouldn't cost much to try. Maybe make a twelve inch quilt sandwich and try some different threads. Make notes with a permanent marker on your sandwich to remember which is which. Hmmm, maybe I'll do that. Thanks!