Sure. We've made grungebuster mats in black. Sonic results are not quite as good. Adding any pigment or dye subtracts a little from the sonic perfection that the grungebuster Turntable Mat achieves. Likewise with our Way Excellent II Turntable Mat, introducing black to the white foam base (even just a little to achieve a gray), has been detrimental sonically.
BTW, the grungebuster mat is not white; it is a creamy beige color. If black is required, consider Herbie's black Donut, a different formulation entirely, does very well with acrylic platters and other turntables that don't need a thicker mat.
SteveHerbie's Audio Lab