No. A wood or bamboo cutting board should never be left soaking overnight, and ideally never soaked at all. Hours under water let moisture travel deep into the board, much further than a wash ever reaches. As it dries, the board can warp, its surface can turn rough, and in the worst case it can crack.
The good news is that one soaking is usually survivable if you dry the board the right way. Here is what happens in the sink, what to do instead, and how to bring a soaked board back.
What a night in the sink does
Water goes deep, and it goes in through the ends first. Wood is hygroscopic: it takes in and gives off moisture. A quick wash wets only the surface. Hours of immersion give water time to work its way in, and it moves fastest along the grain, which means in through the cut ends of the board, where the fibers are open.
The board swells unevenly. As wood takes on moisture it swells, and as it dries it shrinks. In wood, that movement is far greater across the grain than along it: shrinkage across the grain runs about 2 to 10 percent, along the grain only about 0.1 to 0.3 percent. A board that has soaked up water at the ends and on the submerged face swells more there than elsewhere.
Drying pulls it out of shape. The trouble comes the next morning. Pulled from the water and laid flat, the board dries from the exposed face while the face against the counter stays wet. Uneven drying builds stress inside the wood, and that stress shows up as cupping, twisting or, when it is severe, splits and cracks.
The surface roughens. Water swells the short fibers at the surface and lifts them. Once dry, a soaked board often feels fuzzy, a condition called raised grain.
The oil washes out. A long soak in warm, soapy water pulls oil from the outer fibers. A board that beaded water the day before may drink it the next.
Bamboo is a grass rather than a wood, and it is less porous than many traditional hardwoods, so it absorbs less liquid. It is still a natural material, and like any wooden board it can warp or crack with extreme or uneven moisture exposure. A night underwater is exactly that.
Why people soak boards in the first place
Almost every overnight soak starts with a good intention. Each one has a better method.
Stuck-on food. Dried dough, cheese or rice comes off with a bench scraper or the back of a knife held at a low angle, then a brush with hot soapy water. A few minutes of contact with a wet cloth softens the worst of it. Minutes, not hours.
Smells. Garlic, onion and fish odors respond to a scrub with coarse salt and half a lemon, or a paste of baking soda and water, followed by a rinse and a full dry. How to remove stains and odors from a cutting board covers both.
Sanitizing after raw meat. Sanitizing is a flood, not a soak. Wash the board first with hot soapy water, then pour over a solution of 1 tablespoon of unscented liquid chlorine bleach per gallon of water, let it stand on the surface for several minutes, rinse with clear water and air dry. Can you use bleach on a wooden cutting board explains the method in full.
Running out of time. The most common reason of all. If the dishes have to wait until morning, wipe the board, rinse it and stand it on edge in the dish rack. That takes a minute, and the board waits safely.
The right way to wash a board
The routine that keeps a board flat and smooth is short:
- Scrape off food scraps.
- Wash both faces and the edges with hot water, dish soap and a brush.
- Rinse under running water.
- Towel off right away.
- Stand the board on its long edge to finish drying, so air reaches both faces equally.
The whole job takes two or three minutes. How to wash a bamboo cutting board walks through it, and the same steps work for any wooden board.
If the board has already soaked overnight
Do not panic, and do not rush it. A board that has soaked once can often be saved if it dries slowly and evenly.
1. Take it out and wipe it. Pull the board from the water, rinse off the dishwater and towel both faces and every edge as dry as you can.
2. Stand it on edge in open room air. Not flat on the counter, not leaning against a wall with one face hidden. Both faces need equal access to air. A dish rack or a plate stand works well.
3. Keep it away from heat. No oven, no hair dryer, no radiator, no sunny windowsill. Drying wood too fast is what causes it to crack and distort. Patience is the repair.
4. Give it time. A board that soaked all night can take a day or two to dry through. Turn it end for end now and then, so neither end sits lower and wetter.
5. Check it once it is dry. Lay it on a flat counter and press each corner. If it sits flat, move on. If it rocks, it has cupped or twisted. A mild cup often settles on its own over a few more days on edge. A stubborn one needs the steps in how to flatten a warped cutting board.
6. Smooth and oil. If the surface feels fuzzy, sand it lightly with 220-grit paper along the grain and wipe off the dust. Then oil it generously with food-grade mineral oil, both faces and all edges, and let it soak in overnight. A board that has been soaked is dry in its outer fibers and will often take two coats.
If a board smells musty after drying, or shows dark spots that were not there before, see how to get rid of mold on a wooden cutting board.
When soaking has done lasting damage
A crack that runs from an edge into the board, or one you can catch a fingernail in, is worth taking seriously. Food and water collect in it, and it tends to widen with each wash. A board with a deep crack is usually ready to retire from raw-meat duty, and often from cutting altogether.
A warp that will not settle makes a board unsafe to cut on, because it rocks under the knife. Flatten it or replace it.
Most boards never get here. The ones that do have usually been soaked again and again, or soaked and then dried flat or by a heater.
A board that lasts
The best protection against soaking is the habit that makes it unnecessary: wash, wipe, stand on edge. Oil keeps water from getting in during the brief time it is on the surface, and a few drops of water tell you when it is wearing thin: if they bead, the board is protected, and if they soak in, it is time for oil. How to oil a bamboo cutting board covers that test and the routine.
A bamboo board looked after this way stays flat and smooth for years. The WONAMU. bamboo cutting board is 12 by 9 inches, with a perimeter juice groove, and it ships with a cotton care cloth for wiping and oiling. For keeping its shape over the long run, see how to keep a cutting board from warping.
The short version
Do not soak a wood or bamboo cutting board overnight. Long immersion drives water deep into the board, mostly through its ends, and uneven drying afterward can warp it, roughen it or crack it. Scrape, wash, rinse, towel and stand it on edge instead. If it has already soaked, dry it slowly on edge away from heat, check that it sits flat, sand any fuzz and oil it.
❋
WONAMU. makes a bamboo cutting board designed for daily prep, 12 × 9 inches, bamboo, with a perimeter juice groove. Available on Amazon.
Designed by nature.
