(You can also read a summary of this on Instagram)
Q: "I got a stain on the cutting board. How do I get rid of it?"
I've gotten this question more than others, so I've been meaning to write out the "long answer."
First, the short answer:
A: Keep washing and drying the board as normal and the stain will fade on its own.
What's interesting is that the stain isn't really disappearing or "washing out" of the board. It's moving deeper into the wood until you can't see it.
If you're interested in how that works, read below:
What happens when a drop of berry juice lands on the cutting board?
When berry juice lands on a cutting board, some of that juice will remain on top of the board and can be rinsed off.
The rest of the juice will be absorbed into the wood, and the pigment that has been absorbed into the wood cannot easily be washed out.
The best thing to do is simple: wait for the stain to move deeper into the wood over time, until it is no longer visible.
(You could also grind part of the wood away with sandpaper before the stain is absorbed deeper. This may remove some of the stain, but probably not all of it. And since sanding the board down should not be a very regular maintenance step, we don't recommend it in most cases.)
Why do stains get absorbed?
First, a couple of basic concepts about wood:
Wood is built to move water.
Trees move gallons of water from their roots to their leaves each day, and wood's structure contains many tiny "straws" that make this movement possible.
Wood tends toward an equilibrium of moisture.
If wood becomes wet in one area, it begins to transport the water through those "straws" until the moisture is more evenly distributed.
What happens when you rinse your cutting board?
When you rinse a cutting board, the surface of the cutting board will be wet, and the inner "core" of the cutting board will be dry.
Because the wood will try to find equilibrium, it will immediately begin moving water from the outside of the wood to the inside.
This creates a natural "pull" away from the surface, toward the inside of the wood.
How does this affect stains?
Simply put: water will pull some of the stain from the surface of the cutting board to the interior of the wood every time you wash it.
It will naturally fade, and when it is no longer visible, this means the stain is now "inside" of the wood.
But do I want there to be stains inside of my cutting board? Is that a problem?
The principles described here do not only remove stains visually, but also help wood clear bacteria from its surface.
When you rinse a cutting board, water can pull both stains and bacteria down into the wood. While this might sound like a problem, once the wood dries out, bacteria typically do not survive. In lab tests, they have also been shown not to return to the surface of the wood.
This is why bacteria have been observed to survive longer on plastic cutting boards than wooden ones.
So in short: no, it is not a problem that the wood absorbs the stain. This process helps the wood do what some have called "self-cleaning."
You can read more about how this works in: The Science of Wood and Water
Summary:
What really happens to a stain on a wooden cutting board:
- The top layer of the stain rinses off
- The rest sinks deeper into the wood until it fades out of sight
- This happens without extra effort, so just keep using it as normal
Do not attempt to soak the wood or rush this process. That can damage the wood