Do you think all whetstones are the same and suitable for the knife you're using? Did you know that the most important factor in choosing a whetstone is its compatibility with your kitchen knife?

As we know, there are currently many types of natural and synthetic whetstones available on the market. However, it’s certain that some whetstones are not suitable for the kitchen knife you’re using due to the properties of the stone itself—not all expensive whetstones are a good match. Moreover, compatibility also depends on the user’s sharpening skills and the intended purpose.

The compatibility with the whetstone depends on the blade material and the hardness level from heat treatment. It is also closely related to the shape of the knife being sharpened. In this article, we will explore how to choose the right whetstone. All the knowledge we share is for reference only—true compatibility should be assessed by the person using the stone and the knife at that specific time.

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However, if the whetstone is too soft, it will release more abrasive particles than necessary, making the sharpening process inefficient and shortening the stone's lifespan. On the other hand, if the stone is too hard, the abrasive particles won't shed properly, resulting in a longer sharpening time with little effect.

Kitchen knives made from high-hardness steel

Basically, a harder whetstone is suitable. It is more effective to use a harder whetstone for a blade made of hard steel.
 

Using a soft whetstone is not necessarily a problem, but its surface will wear down quickly, making it difficult to maintain a flat surface and requiring frequent flattening.
In the case of knives made from well-balanced hardness steel (around HRC58 ±1) such as carbon alloy steel or white paper steel, a hard ceramic whetstone is the best choice.

However, for kitchen knives made from high-hardness steel such as blue paper steel or any steel with a hardness of HRC60 or above, sharpening with a hard stone may feel slippery and ineffective. In such cases, a relatively softer whetstone might be a better match.

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We can also use a hard whetstone, but after sharpening, you may find the edge is not as sharp as when sharpening regular carbon steel. However, this doesn't mean you can't achieve a sharp edge on stainless steel with a hard stone it just means it will require more effort and time, as you'll need to increase the number of sharpening strokes.

Ceramic Kitchen Knives

Ceramic knives are extremely hard and cannot be resharpened with regular whetstones. Therefore, if you want to resharpen them at home, you will need a diamond sharpening stone.

However, even with a diamond sharpening stone, sharpening a ceramic knife is not an easy task due to its extreme hardness. It requires a certain level of skill, and sharpening it can take a lot of time and effort. Therefore, it is highly recommended to consider the manufacturer's warranty or seek help from a trusted store to handle the sharpening for you.

Choosing Based on the Grit of the Sharpening Stone

When we give advice on choosing a sharpening stone based on its grit, we typically refer to four categories: coarse stones, medium stones, finishing stones, and ultra-finishing stones. In most cases, we recommend using a medium grit stone (ranging from #600 to #2000), as it is sufficient for almost all sharpening needs without significant issues.

Coarse Sharpening Stones

Coarse stones are used for initial processing, such as fixing chipped blades or significantly reshaping the edge. If the blade has no major damage, these stones are rarely needed. The grit typically ranges from #80 to #400, with abrasive materials made from silicon carbide.

Medium Sharpening Stones

Medium stones are used for general sharpening, helping to refine the edge and create a solid cutting line. Most kitchen knives can be efficiently sharpened with this type of stone and will be ready for use without issues. However, it still leaves fine scratches. If you're particular about achieving an extremely sharp and aesthetically flawless edge, follow up with a finer grit stone. Medium stones usually range from #600 to #2000 in grit, with abrasive particles typically made from alumina.

Finishing Sharpening Stones

Finishing stones are used to eliminate the fine scratches left by medium stones and serve as the final stage in the sharpening process. Their purpose is solely to enhance the smoothness and sharpness of the knife edge. Finishing stones typically range from #3000 to #6000 in grit, and their abrasive particles are primarily made from soluble alumina.

Ultra-Finishing Sharpening Stones

An even finer finish is applied to the edge of a kitchen knife that has already been sharpened. This is especially favored by chefs who value the appearance and razor-sharp edge of their knives. The main goal is to remove any micro-scratches left by the finishing process, leaving the blade polished to a mirror-like surface that is incredibly sharp and refined. Ultra-finishing stones have a grit level of #8000 or higher, with abrasive particles primarily made from ultra-fine soluble alumina.

Many users prefer to use natural whetstones exclusively for the final finishing stage, as they are known for delivering a unique edge and aesthetic. The number of sharpening passes and the specific techniques applied during the process are often considered a craftsperson’s secret, developed through experience and personal refinement.

Combination Whetstone

A combination whetstone is a sharpening stone with two different sides. These two surfaces may vary in grit level, material, or even color. This dual-function design allows users to perform both rough sharpening and fine honing using a single stone. The choice of combination depends on each user's preferences and sharpening needs.

Choosing Sharpening Stones Based on Other Criteria

Choosing the right sharpening stone also depends on the shape and size of your knife. Avoid using a sharpening stone that is too small for long or large knives, and likewise, avoid using a stone that is too large for small knives.

For example, when sharpening a large knife on a small stone, you will need to repeat the process multiple times to cover the entire edge, which is time-consuming and inefficient. On the other hand, if you use a large stone for multiple small knives, the stone will wear unevenly, especially in the frequently used area, causing the surface to become uneven over time.

That said, it's not necessary to prepare multiple stones of different sizes. Instead, consider adjusting your sharpening method, such as dividing the stone surface in half and using each half alternately to prevent uneven wear.

If you use Santoku, Petty, Yanagi, Deba knives, etc., a standard water stone size around 200x60x30mm—commonly available in most stores—is sufficient. It’s recommended to use a combination stone with two sides of different grit levels, and a base for stability. Choose a larger stone only if you sharpen knives frequently and want faster results.

For serrated knives or specialty blades, you cannot use a flat sharpening stone. For serrated edges, sharpen each tooth individually with a rod-shaped sharpening stone. For saw blades, use square rod stones or files. Even manufacturers rarely re-sharpen serrated or saw blades because it is generally unnecessary.

Now you know how to choose the right sharpening stone for your kitchen knives.