While you can technically sublimate a black T-shirt, and the ink will transfer off the paper and onto the shirt, you won’t be able to see the image. This vibrancy issue is because dye-sublimation ink is translucent, and the cyan, magenta, yellow, and black ink cannot change the color of the black fibers.
The only way to get around this is by first printing onto a special vinyl or heat transfer paper made for dye-sublimation and then pressing the vinyl or paper to the shirt. However, in this case, you are not directly sublimating the T-shirt. There will be both a physical feel or “hand” to the print as well as reduced washability.
—Coastal Business Supplies