What is a Whetstone & How is it Made?

Posted by Tara Hohenberger on

Japanese whetstones are essential for maintaining the sharpness of high-quality blades, particularly those made from the fine-grained steel used in Japanese knives. Japanese whetstones come in various grit sizes, ranging from coarse for initial sharpening to ultra-fine for polishing and finishing edges, allowing for precise blade maintenance.
For a lot of our customers, the more someone learns about Japanese knives the greater their interest in knife sharpening. Nothing will restore a dull blade to a sharp edge better than whetstones or waterstones. In this article we’ll discuss Japanese sharpening stones in depth, including history, types and materials. Some might ask if it is better to use a knife sharpener or a whetstone? When it comes to Japanese knives, the answer is without a doubt to sharpen with a whetstone.

The History of Whetstones

Whetstones also known as water stones or sharpening stones are believed to have been in use since 79 AD. Some global regions with evidence of using stones containing compounds such as novaculite or sedimentary shales to sharpen metal and produce a cutting edge are Japan, Belgium, England and Arkansas, USA.

Whetstones, Waterstones, & Sharpening Stones

Simply put, a whetstone is a stone used for sharpening tools and knives. The name derives from an antiquated word ‘whet’ meaning to sharpen. So essentially a whetstone is used for sharpening and therefore it is a sharpening stone. Is a whetstone the same as a water stone? A waterstone is a type of sharpening stone where water is used as the lubricant. What about oilstones? Oil stones are sharpening stones where mineral oil is used as the lubricant, you might have heard of Arkansas stones, which are naturally mined in Arkansas, United states and popular for sharpening, however, when it comes to Japanese knives, we strongly recommend water stones. Is a honing rod a sharpening stone? No, a honing steel can correct an knife edge’s alignment, but doesn’t remove metal and therefore not actually sharpening your knife.

Types of Whetstones

As you might have guessed there are many types of whetstones out there. In the following paragraph we’ll cover the two main types of stone relevant to knife sharpening, synthetic whetstones and Japanese natural stones or JNATS . Visit our sharpening section to see the best sharpening stones available to sharpen kitchen knives.

Natural Whetstones (JNATS)

Japan is one of the places with the most natural stone formations for cutting whetstones. The most sought after region for mining whetstones is near Kyoto. It is believed that availability of whetstones and their relations to sword crafting is one of the main reasons Kyoto was selected as the capital of ancient Japan.

Japanese Natural Whetstones are prized for their ability to create very refined edge finishes and produce contrasts in polish levels.

How are whetstones sourced and processed? Japanese water stones are quarried in Japan. The stones are cut from sedimentary rocks using a diamond saw. Because of their unique composition — fine silicate particles within a sedimentary clay like material, the resulting stones are unable to be assigned a grit number. Japanese water stones are much softer compared to synthetic sharpening stones.

Synthetic Whetstones

Synthetic stones are made by suspending abrasive particles in a binder material, usually ceramic like silicon carbide or aluminum oxide. The ceramic is fast cutting leaving the abrasive compounds to abrade the knife’s edge.  Repeated use will create a divot, so it’s important to use a flattening stone to maintain a level surface for sharpening your knives.

Understanding Grit Size

The lower the number of the grit the more abrasive the whetstone will be. Low, coarse grit whetstones remove steel quickly and should be used for repairs or on very dull knives. Medium grit stones should be used to restore edges on moderately dull knives with the highest grits reserved for polishing edges. The variety of stone grits give you the freedom to decide how much metal to remove from the edge, and how fast you want to go. The level of control is one of the reasons why stone sharpening is better than other knife sharpening methods to achieve a sharp knife.
    • Course Grit
400 grit: Not necessary for everyday sharpening, but useful for small repairs and very dull knives.
    • Medium Grit
1000 grit: This is the standard medium grit best for regular sharpening. We recommend starting with 1000 grit for most sharpening situations.
    • Fine Grit

4000/6000 grit: A fine grit stone in this range is considered a polishing stone, and the higher the grit, the finer the polish on the knife’s edge. The grit you choose will be determined by how you use the knife. For example, if you use a slicing knife to cut raw proteins, you might want a slightly less polished finish for ‘grip’ when creating thin slices.

8000 grit: An #8000 stone is a fine grit polishing stone which is meant to complement a #4000 or #6000 stone. If you're looking for a very refined edge on your knife, this is the ideal stone to finish with.  Are higher grits available? Yes, some natural stones, ones that are mined from a mountain and will be higher grit (creating a smoother surface) than typical synthetic sharpening stones. High grit polishing stones create a mirror like finish on the edge of the blade. Is higher grit better? Not necessarily. 


We hope we answered some of your pressing questions about the history and variety of whetstones. Check out our blog for other resources for keeping your knife blade razor-sharp including How to Sharpen a Knife with a Whetstone.

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