I know black is a very hard thread to dye per thread manufacturers. One of the first questions people in the know ask if I am having trouble with thread breaking is "is it black" because of the difficulty in dying it, it apparently weakens the thread. I don't know if this is true for the older threads as maybe the black dyes back then just didn't "dye" the cotton as well and so are easier to fade with chemicals? Don't know how my comment helps. I sort of like the variegated look too.