Why and How Should You Oil a Wooden Cutting Board?

Wood is not alive, but it is still a breathable material. The spaces between its fibers absorb and release moisture; the wood swells when it takes in water and contracts as it dries. In the kitchen, this cycle happens several times a day, and with each cycle, the fibers at the surface lift a little more. Raised fibers catch the knife and draw juices from cut ingredients deeper into the board. Oiling does not stop this cycle; its purpose is to slow it down. An oiled board absorbs less liquid from cut ingredients, which is also the main reason odors linger less in the wood.

Oil enters the pores and stays there, making it harder for water to fill the same spaces. To do this, the oil needs two properties: it must be fluid enough to penetrate the wood and must not spoil over time. Olive, sunflower, and corn oils used in the kitchen meet the first requirement but not the second; because they are unsaturated, they slowly turn rancid inside the wood, eventually leaving an odor that will not come out of the board. Washing does not remove that odor. For the same reason, butter or shortening rubbed onto the board will not work; both spoil in the wood and leave a sticky layer on the surface.

Use food-grade mineral oil for this purpose; it is odorless, tasteless, and does not turn rancid. The process is simple: dry the board thoroughly, pour on plenty of oil, and spread it over every surface with a clean cloth—the top, bottom, and all four edges. The sides and edges are the areas most often missed, even though cracks often start there. Leave the board for one night; the next day, wipe off any excess oil that has not been absorbed with a dry cloth, and return the board to use.

Decide when to oil the board by observation, not by the calendar. Drip a few drops of water onto the surface: if the drops bead up and do not spread, the pores are still full and the board does not need oiling. If a drop is absorbed immediately and the wood darkens at that spot, the oil is depleted. It is normal to oil a new board more often during the first few weeks, then less often over time. Let the board itself guide the decision; two boards in the same kitchen may need oiling at different intervals. To see whether the color has darkened, test the area that gets the most cutting and washing, not the center of the board.

Some habits undo the benefit of oiling in a single go. Leaving the board to soak in the sink, putting it in the dishwasher, or leaving it flat after washing wipes out the oil’s effect. Wipe a washed board right away and dry it upright, with both sides exposed to the air; a board left wet on only one side swells and warps. Mixtures of hardened beeswax and mineral oil leave a more lasting layer on the surface.