While you don't have to be as particular with whetstone care as knife care, it is still important to keep your whetstones in prime condition.
If a whetstone hasn't been properly cared for or stored, it could wind up with cracks on it or worse, which severely impacts its lifespan. A crack generally can't be fixed, let alone if a whetstone splits in two.
Here's some tips to make sure you don't accidentally damange your whetstone, or amplify any damage currently on it.
Be very careful not to crack the whetstone
The most important part about whetstones and their maintenance is to make sure that they don't break. This can happen unexpectedly - you might open your storage case only to find one of your whetstones has cracks or has even split in two! Whetstones are very susceptible to changes in temperature and humidity, natural whetstones even more so, being regarded as highly delicate tools. This kind of damage is somewhat preventable though, using the care tips below:
-When you've finished using your whetstones, wipe off any moisture and properly dry it.
Cracks can occur due to temperature changes when stored with moisture still on or in the stone. Dry them thoroughly before putting away.
-Store your whetstones out of direct sunlight
Direct sunlight can cause your whetstones to crack, so store them indoors in a darker place. A storage case for your whetstones can work well here.
-Store your whetstones in a place where temperature and humidity is more constant
As written above, whetstones are sensitive to changes in temperature and humidity. Keep them away from items like humidity changers and temperature controllers.
-If you have multiple whetstones, don't stack them
Whetstones will crack or break from too much weight being placed on them. If you store multiple on top of eachother, the lower ones have a high chance of cracking.
Be careful not to soak your whetstone too much in water
It's easy to think that before you sharpen a knife on a whetstone, that you need to soak the whetstone first.
This is indeed the case with "vitrified method" whetstones, as they're quenched and molded at over 1000 degrees Celsius during their manufacturing. This strongly bonds the abrasive grains in the stone, meaning they'll suffer only very slight deterioration from exposure to water. To get the water to properly penetrate the stone however and make it usable, it needs to be soaked - normally for about ten minutes, but this may vary.
However, there are other kinds of whetstones that should not be soaked. These are "resinoid method" and "magnesia method" whetstones, which are both hardened by baking at lower temperatures or simply letting them dry naturally. This leaves a lot of binding agent inside these kinds of stones. If these stones are soaked in water, this agent weakens, which is what is holding the abrasive grains together. This can cause the stone to crack or even break apart if soaked for too long.
A quick way to tell what kind of whetstone you have is to submerge it under some water. If you see lots of bubbles coming from the whetstone, it's a vitrified one and is meant to be soaked. If you don't, it's one of the other two types and should not be soaked. To use those whetstones, just a splash of water on top is enough.
Don't let the whetstone get clogged
You might find your whetstone has become slippery over time, due to grinding debris getting stuck in the abrasive grains on the whetstone. This is called clogging, and tends to happen with magnesia method whetstones. We have a full article on clogged whetstones you can read, but in short rubbing two whetstones of the same grit number together will fix this, or by using a dressing stone made specifically for the purpose of fixing clogging. Most of our finishing stones come with this dressing stone included.