One of the permanent and essential fixtures in any kitchen, a good wooden cutting board allows anyone to quickly prepare diced or sliced ingredients, such as meats or vegetable, without damaging your counter tops. But what should you do if you find that your brand new maple or walnut cutting board is starting to look curved rather than straight? This is the result of your cutting board becoming warped, but it is not cause for it having to be thrown out or trying to get a wholesale cutting board for cheap. There are measures, both preventative and reactive, that can help you keep it from warping and to restore it to its natural state if it does warp on you.
The easiest way to address this issue is to prevent it from happening in the first place. Avoid submerging your cutting board in water for extended periods of time. Just try to keep from leaving any water on one side at all. Also, try not to make a habit of placing very hot items on it regularly. This includes removing pots or pans from the stove and taking out dishes from the microwave and resting them on top of a cutting board. Keep it seasoned and oiled to prevent any moisture damage from the air (this entails using such ointments such as lemon juice, beeswax, mineral oil or even carnauba wax). Finally, always store your cutting board horizontally after washing it in how water, as vertical storage leave it more susceptible to bending since there isn't a stable surface underneath to preserve its straightness as it dries.
But some of us forget, so we end up with either a convex or concave shape to our wooden cutting board. So the easiest way to fix this is to break one of the rules from above and submerge your cutting board in warm water for a couple of hours. Next, lay it on a flat surface after drying and place another flat object on top. Then, start stacking as many heavy objects on top of that object, like books or weights or anything heavy. Let it sit for 2-3 days for the wood fibers to return to their natural shape as they dry.
If this method is ineffective, you can get a large pot and fill it halfway with water. Put a steel colander over the opening, then lay the bump of your warped cutting board face down on the colander and start simmering the water inside the pot to boiling. Hopefully, this will help the wooden fibers expand and will lead to the board flattening out once again.
If you prefer a more proactive approach to solving this issue, get an clothes iron. Next, wet a medium-sized kitchen towel and drape it over your warped cutting board with the bump facing up. When the iron is hot enough, start ironing the towel and thus the board as you would a pair of pants, making sure to apply plenty of pressure and using the steam button often. This mixture of pressure and heat with help reshape the fibers in the wood.
Please not these three solutions may cause your board to crack. Try them at your own risk!
If none of these methods work, and you have a large enough cutting board, try sawing off the part that is warped or even using a planer or wooden sander to even out the its shape. Planers are available at most hardware stores, but you may need to find someone with a large enough sander in a wood shop if you want to sand your board flat.