Examples from the Web for ink in
Ink-in with acid-proof color which will color the whole stone.
Now clean the stone well with water, ink-in with acid-proof ink, and etch it again as has been described several times.
Ink-in the stone very clean, and coat it with gum and water that is very thin and delicate.
Then clean the stone with oil of turpentine and ink-in well with acid-proof color.