Quite the same technic here. Depanding of the black tone you want finally, you can change the dark grey drybrush for a dark blue, or even a dark purple drybrush.
And finally, I make a washe with a ink based product (for washes, I prefer ink rather than diluted acrylic paint)
BTW, sometimes, mate acrylic black paints are almost "anthracit" or very dark greys, so you can directly paint it in black then shade it with a very deep black ink.