Tone on tone is for example, a white fabric with a white design printed on it. It can be any color, but the most popular and easy to find are white and beige. I would not use muslin for machine embroidery (I assume that is what you are doing) because it shrinks. Also, muslin is not a great quality material. For machine embroidery I want my fabric to be the best quality I can afford. Plain white works great for me.