Then I wondered what would happen if I combined two threads - a strand of white and black. I tried it and the two on the bottom are the results. The one on the bottom left was made with size 10 crochet thread and the one on the bottom right was made with size 30 crochet thread.
It was interesting to see the effect of the two threads held together and treated as one thread.
With the thin threads the black disappears when it is worn.
Both colors show with the thicker thread.