A whetstone is made of abrasive particles and binder materials.

These particles are harder than steel or stainless steel.

And the binder material is sticking the particles together.

When you sharpen your kitchen knife,

These hard particles and the knife metal grind together and it shaves the knife edge.

Doing so, the knife edge forms a zig-zag shape like you can see on a saw.

And it makes a knife sharp.

1. Actually, it is fun to use a whetstone

In 2003, at Homecenter Kohnan, I bought my first whetstone.

It was a sweltering summer day.

My first santoku knife was dull, so I wanted to do something about it.

It has been 3 months since I started living by myself.

There was no longer my dad to sharpen the kitchen knives.

Sharpening was fun and did the job…

2. Even Millennium Falcon the fastest ship in the galaxy needs repair

So do your kitchen knives.

It doesn’t matter how expensive it is or how hard the metal of the blade is.

And a whetstone comes in handy.

3. Sharpening a kitchen knife means grinding the blade

A sharp knife has a thin edge. And the edge has a zig-zag shape.

You have to keep these shapes using a whetstone once in a while. Because…

After using the knife for a while, this zig-zag shape disappears and it becomes a straight shape.

If the edge has a straight shape, then your knife is completely dull.

This is because the knife edge keeps hitting the cutting board.

And the zig-zag peaks get rounded.

Sharpening means bringing the zig-zag shape back to the knife edge.

4. Whetstones have so many kinds

There are natural whetstones, artificial whetstones made with binder materials, and artificial whetstones that are created by electroplating.

These categories have their own subcategories.

Especially artificial whetstones have a lot,

Because there are so many materials.

5. Long ago, all knife sharpeners used natural whetstones

The stone is harvested from the rocks from the hard strata, and then the surface is flattened.

Nowadays, natural whetstones are very expensive.

Because the number of whetstone mines have decreased.

You also need to check the quality of the stone by eye since all stones are different.

So having a natural whetstone has a high threshold.

6. Artificial whetstones are invented in the U.S.

It was at the end of the 19th century.

While people there were trying to create an artificial diamond, they discovered this abrasive for whetstones.

An artificial whetstone is made of abrasive particles and binder materials.

Nowadays, almost all whetstones that you can find at a homecenter are artificial stones.

Unlike natural whetstones, these kinds of stones don’t have unevenness.

The size of the particles in the artificial whetstone are all the same.

So it is much easier to use.

7. There are two important abrasives… Fused alumina and silicon carbide abrasives

These are both popular whetstone materials.

Fused alumina has better abrasion resistance, and…

Silicon carbide is harder.

8. Typical fused alumina abrasives are white almina(WA) and almina(A)

These abrasives have better abrasion resistance,

This means they are harder to wear out.

So it is used for medium whetstone (#400 – #2000) and fine whetstone( #3000 –)

Whetstones that are made of WA and A are great to sharpen stainless steel knives.

9. Typical silicon carbide abrasives are green carbon(GC) and carbon(C)

Silicon carbide abrasives are hard, so they are used for coarse whetstones(#80 – #320).

Green carbon(GC) has higher purity than carbon(C)

And as the name suggests, it has a green color.

10. Solidifying methods are important too

A whetstone is made of abrasive particles and binder materials.


The binder materials retain the abrasive particles together.

There are 3 standard solidifying methods to make whetstones.

Firing up in high heat to solidify(over 1000C),

firing up in relatively lower temperature to solidify(around 200C),

And drying to solidify.


Binder materials are also different from the solidify methods.

11. Vitrified whetstone are solidified by firing up in over 1000C (1832F)

It is made of abrasives and feldspar or soluble clay.

First, you make the whetstone shape by press forming, then drying it out.

After that, solidify it by sintering in a high temperature.

It is usually 600C to 1300C.

This solidify method is used very often when the abrasive is green carbon(GC).

Vitrified whetstones are also called ceramic whetstone. Because…

The manufacturing process is the same as baking pottery.

12. Pros of vitrified whetstones are high grinding power and durability

Vitrified method has strong bonds to keep abrasives tight.

So this whetstone is hard and has a high grinding power, 

And it is not easily deformed.

13. Cons of vitrified whetstones are soaking time and lack of elasticity

You need to soak a vitrified whetstone for a long time before you use it.

As I said, it is hard, so it doesn’t have as much elasticity as other types of whetstone.

The surface of the blade tends to be little rough,

Don’t use a vitrified whetstone if you need to do some delicate job.

I recommend having this for…

Coarse stone (#80 – #320) and medium stone (#400 – #2000)

14. Resinoid whetstones are solidified by firing up in 200C(392F)

This is made of abrasives and binder as phenol resin, epoxy resin, or polyamide resin.

These thermosetting resins solidify by heat.

Resinoid whetstones don’t have grind power as much as vitrified whetstones.

So these whetstones are often used for finishing.

It is a popular type for fine whetstones (#3000 –).

15. Pros of resinoid whetstones are elasticity and thoroughness

A risinoid whetstone makes your knife blade really smooth.

Especially when you use a fine resinoid whetstone,

It makes a beautiful mirror polished blade.

You don’t need to soak in the water before using this type of whetstone.

You just need to sprinkle some water while you use it.

16. Cons of resinoid whetstones are low grinding power and less durability

Resinoid whetstones have low grinding power. This is because binder resin in these stones has  elasticity.

It is a good thing if you want to do delicate sharpening, but…

If you want to shave the blade a lot, it will be the downside.

Resinoid whetstones are softer than other whetstones.

So it gets worn out faster than other stones.

In addition, you shouldn’t soak it in the water for a long time.

It will cause deterioration of the stone.

17. Magnesia whetstones are solidified by drying

This is made of abrasives and cement like magnesia oxychloride.

After kneading them, you make a shape of a whetstone and dry it.

18. Pros of magnesia whetstones are usability and grinding power

You don’t need to soak this kind of whetstone in water. 

Magnesia whetstones have a good amount of grinding power. In terms of grinding power, it comes next to vitrified whetstones. 

Magnesia whetstones have large varieties of finesse for magnesia whetstones.

From coarse whetstones to fine whetstones.

It also gives your knife a smooth feeling when you use it.

19. A con of magnesia whetstones is degradation over time

This is because magnesia whetstones are not sintered during the production process.

It might have cracks if you use it for a long time.

20. The other kind is a steel plate coated with diamond grit

This kind of knife sharpener is made of a steel plate and diamond grit.

The grit is bonded by electroplating.

Sometimes, this kind of knife sharpener is made of  boron nitride grit, or other grit instead of diamond.

21. A con of electroplated plates are strong grinding power 

It is made of diamond particles.That means it is really hard and durable.

You cannot sharpen a ceramic kitchen knife with a regular whetstone because ceramic blades are really hard, 

But a diamond sharpening stone can do the job.

With little to no effort.

You can sharpen your knife real quick because of this strong grinding power.

You can save time using a diamond sharpener.

Usually, this type of diamond plate is used as a coarse whetstone.

It stays flat, so you don’t need to flatten it.

In addition:

A diamond kitchen knife sharpener is very useful for flattening regular whetstones.

This is because again, It stays flat all the time.

22. A con of electroplated plates is that some knife blade are incompatible

Some knives rusts super quick after sharpening your knife with a diamond stone.

This happens because of galvanic corrosion.

Two different kinds of metal touching each other in the water cause this reaction.

In our case, the kitchen knife blade, the base of the diamond sharpener, and the running water.

In order to avoid your kitchen knife rusting,

You need to sharpen with a regular whetstone after using the diamond stone.


You need to use baking soda water while you are using the diamond stone.

This way, you can bring the ph to alkaline.

So you can prevent it from rusting.

The other con of a diamond stone is…

If you are not careful, you might destroy your knife

It is too easy to grind the blade when you use a diamond stone.

You can sharpen hard metal materials like ATS-34 steel, high-speed steel, or vasco wear steel with no problem. It is too powerful.

So if you are not careful your blade will be worn down very quickly while you are sharpening.

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