Unfinished Wood Is Naturally Self-Cleaning and Anti-Bacterial

Wood is HYGROSCOPIC. This means that wood equalizes the moisture content of its environment. If there is more water in the air, the wood will absorb water. If the air is dryer than the wood, the wood will lose water through evaporation. If dry wood gets wet, it will absorb some of that water, even as the rest of the water evaporates. So here's the amazing part. Wood is porous, this is how the tree transports water and nutrients when it's alive. When wood gets wet, some of the water evaporates directly into the air, but some of the water is absorbed into the wood. It soaks it up like a sponge, but on a much smaller scale. As the wood absorbs water from its surface into the microscopic pores, it draws any bacteria that may be on the surface of the wood down with it. The bacteria then gets trapped inside the wood, in the spaces between the wood cells. Once the surface water has been absorbed and evaporated, the wood surface is dry. Remember that wood is hygroscopic. Since there is now more water inside the wood than in the air, the wood begins to give up that interior water. But guess what? The bacteria don't come back out, they stay in the wood, where they meet their demise. Bacteria need water to survive. When the moisture content gets too low, they die. This process begins right away, but takes about 12 hours to complete depending on the humidity level where you are. If you wash your cutting board after dinner and leave it out to dry, it will be clean by morning.

So as you start to understand how this works, your next question may be, what happens if you put some oil, or wax or waxy oil or oily wax or super organic plant based, vegan, non-petroleum board butter finishing cream on the board? Every high-end cutting board that I've ever seen for sale has some kind of finishing oil on it, and usually some sort of additional finishing oil is conveniently sold by the same company who sold you the board. This is for two reasons. First, the oil makes it look nice. This is the main reason that most wood is finished, the finish increases the contrast in the wood grain and makes it shiny. Second, It's an up-charge. It's another thing that you can be sold.

The important thing to know is that when you put any kind of finish on wood it looses its ability to move water and therefore, to kill bacteria. Here’s a LINK to some peer reviewed, scientific papers that explain this.