I use archival white ink from Hobby Lobby, the darker the osage gets the more it stands out. I put a couple of coats of tru-oil down first and multiple coats over the lettering after it dries. I use an extra fine nib calligraphy pen. It take a little doing to get the ink to flow just right, I put a drop of ink on the underside of the nib, make a line on a piece of cardboard to get things flowing then go to the bow. Sometimes I will start getting skips and have to wipe off my lettering with a wet paper towel and start over, the ink is acrylic and waster soluble.