There is an ancient traditional Japanese wood finish to make houses resist fire and rotting. The finish is based on the discovery by the ancient Japanese that it is harder for something already charcoaled to catch fire again. 
Next take a brush with firm bristles and dust off the board. This leaves some sheen on it in the woodgrain. Wash off the remaining dust.
Once a year, reapply the oil as a spray to keep this finish, or let it age naturally outside. The resulting finish has a dynamic appearance. From different angles the board can look black, silver, or dark brown.
