That's alkanet root boiled in alchohol and mixed into linseed oil. About 6 applications wet sanded 600, 800, 1000, 1200, 1500. Top coat is Dig/salopian oil finish, coat a day for a month. Last 4 coats, I added a small amount of pure tung oil to the rub. The wood is one of 3 turkish blanks I bought cheap from Ali Denli in Switzerland.