How do I care for my sharpening stones?

Maintaining sharpening stones also known as “dressing” sharpening stones is the process of flattening, and cleaning the surface of the stone so that it removes steel evenly and effortlessly. While it is not a particularly complex process, it is critical to ensure that your stones work as effectively as possible. 

There are many different types of flattening and cleaning stones on the market, but based on my experience, serious sharpeners use calibrated synthetic diamonds adhered to aluminum or stainless steel plates. I use an Atoma flattening plate with an aluminum handle. Mine cost about 80 dollars, but price can vary on brand, availability, and manufacturer’s tolerances during production. 

Synthetic diamond will make quick work of removing high and low spots on the surface of your stone. When you sharpen a knife, you remove steel at a very specific angle, but unless you’re using a diamond sharpening stone, you will also be removing a bit of the surface of the stone. This inconsistent surface will make it much harder to create a consistent cutting edge which is critical to ensure the best possible performance of your knife. 

Before every sharpening session I run a flattening plate across the surface of the stone to ensure that the surface is as flat as possible. If you see a dark section on the stone after a few swipes, you’ve found a low spot. Rub the plate on the surface of the stone (making sure the stone is properly soaked and splashing with water occasionally to keep the grit of the flattening plate unobstructed). When you stop seeing a dark patch, and the flattening plate moves easily over the surface, you can consider the stone flat (if you wanna be absolutely sure, you can hold a straight edge ruler on the surface of the stone and hold it up to the light. If you see light in between the surface of the stone and the ruler, the stone is not flat). Make sure to bevel the edges and corners of the stone to avoid scratching the blade of your knife during sharpening. 

Aluminum oxide flattening stones are also available, but I find that they wear down at a similar rate to my sharpening stones. The result is that I end up needing to flatten two stones instead of one so I stick to diamond. 

In extreme cases, the surface of the stone begins to look a bit like a bowtie, thin in the middle and flaring at the ends. While this isn’t ideal, it’s not irreparable. Most of the time all that means is you’ll have to spend a lot of time with a flattening stone. 

If you can’t find a good flattening plate, coarse emery cloth on a sheet of glass (or really any flat surface) can serve as a quick and effective substitute. Simply lay the emery cloth on the glass, add a little water, and rub the worn sharpening stone against it. Keep both the stone and the emery cloth wet throughout the process to ensure even material removal. Be careful not to accidentally flatten the stone at an angle—spending time on this only to discover an uneven surface can be frustrating. This method isn’t as precise as a dedicated flattening plate, but it’s a solid alternative in a pinch.

Never soak your whetstone in hot water, and avoid soaking it for longer than 10 minutes. Both practices can cause the stone to warp, crack, or even break. Always use room temperature, non-chlorinated water to soak your whetstone to ensure it stays in optimal condition for as long as possible. Proper care during the soaking process will help maintain the stone’s performance and longevity. After you’ve finished sharpening, make sure to flatten the stone, and then leave it to air dry on a dish drying rack (or similar). Do not try to dry it with a towel, and never leave it in direct sunlight.