Sublimation ink is not opaque. Once an image is transferred onto a substrate, the substrate’s color shows through the transferred image. For white- and light-colored shirts, this works out quite well. For darker shirts, the limited color range is typically unacceptable. Keep in mind that you must use colored shirts that are certified for sublimation transfer because a standard colored polyester shirt will un-sublimate its color when hit with heat.
—David Gross, Condé