This is a quick series of pics to show how I stain my Hirst Arts blocks. I use an old jelly jar and fill it about 80% full with rubbing alcohol. Then I add 4-10 drops of black India ink depending on how dark I want the stain to be. Put the lid on and shake well.
Next I use hemostats or tweezers to dip the block into the stain solution.
Let dry for a couple of hours.
I also use sepia colored inks for a nice sandy grey to mix.