Naniwa sharpening stones are the best of the best. Japan's age-old sharpening traditions combined with Naniwa's 80 years of experience guarantee unparalleled quality. Naniwa performs constant quality checks to ensure only the best products are sold. It's this high quality that makes these sharpening stones so popular among those who love to sharpen their own knives.

Naniwa

Naniwa

The Naniwa Diamond Pro sharpening stones are Naniwa’s specialty stones. They are suitable for even the toughest steel types! These Japanese stones consist of an aluminium block, covered in a layer of diamond particles. The stones are bound by resin, optimally matched to the grit size of the abrasive particles. Naniwa Diamond Pro sharpening stones are tough, barely wear out and have a high concentration of sharpening particles.

Naniwa Diamond Pro Stones

Naniwa Diamond Pro Stones

Naniwa Basic Stones sharpening stones are budget-friendly stones for beginners. These stones are of excellent quality, regardless of the price. The Basic Stones are made in Vietnam, where the production process is strictly supervised by Japanese sharpening specialists. The stones are dual-sided and relatively soft compared to the rest of Naniwa's range. That's why it's important to regularly use a flattening stone to keep the Basic Stones in tip-top condition. Because the stones are relatively thick, they will still last you many years.

Naniwa Basic Stones

Naniwa Basic Stones

Sharpening on sharpening stones or whetstones gives you a true sense of craftsmanship. You will get to know the characteristic features of your knife better and better. In addition, your personal sharpening style gives your knife a unique edge. The only thing you need to know is this: how do I choose the right sharpening stone?


## Grain sizes of sharpening stones/whetstones


Which sharpening stone you need completely depends on the state of your knife. And with 'which sharpening stone' we mean 'which grain size'. The blunter your knife, the coarser the stone needs to be. In other words: the lower the grain size. If your knife is still relatively sharp one sharpening stone with a relatively high grain size will be enough (let's say 800 or higher). If your knife is blunt you will need multiple stones. First a coarse stone (grain size 120) to restore the fold, followed by other sharpening stones in increasing grain sizes to sharpen the edge and finally a strop to polish the blade. But you can read more about this in our info-topic about [sharpening on sharpening stones](kato://content/migrated_topic_61).


## Material sharpening stones/whetstones


A whetstone is in most cases a composition of a basic stone, sharpening particles and a binding agent. [Skerper Arkansas](kato://content/migrated_pageid_303) and [Ardennes Coticule](kato://content/migrated_pageid_247) stones, however, are completely natural. The sharpening particles have cutting edges that ensure they can sharpen. As soon as a sharpening stone is used, small parts of the grain break off after which a new cutting edge emerges.


These particles can be made from different materials. Materials often used are carbide, ceramics, aluminium oxide and novaculite. The strongest sharpening stones have a diamond coating that cannot wear out which is also why these stones can be used as flattening stones. Flattening stones can be used to flatten your hollowed out sharpening stone. You can read more about this in the info-topic: [Sharpening stone materials: which are the best](kato://content/migrated_topic_570)?


## Binding agent


The binding agent keeping the sharpening particles together is also important. Synthetic resin is an agent that is often used. But magnesium and ceramic-bound sharpening stones are relatively common. Other binding agents are inorganic compound, nickel, synthetic sapphire and mica. The binding agent used determines the amount of sharpening particles per surface unit and thus how fast and precise you can sharpen. Some binding agents, such as magnesium, however, cannot handle water and can therefore not be submerged in water. Definitely something to take into account.


## Brands of sharpening stones


We sell sharpening stones from all famous brands. Think of [Lansky](kato://content/migrated_pageid_301), [Naniwa](kato://content/migrated_pageid_374), [Shapton](kato://content/migrated_pageid_280), [Spyderco](kato://content/migrated_pageid_317) and many more. Affordable but top-quality sharpening stones are our own Skerper whetstones.

Sharpening stones

There are many different types and sizes of sharpening stones. In this topic we discuss what materials are used to produce sharpening stones and what the (dis)advantages of these materials are. As such you can decide which material will suit you best. Let's start with the short version. Are you interested? If so continue reading to find out more in the extended version!

## In a nutshell:

Sharpening stones can be divided into two categories. Natural sharpening stones and synthetic sharpening stones. Natural sharpening stones are just that, natural stones. These stones were taken from a quarry. Synthetic sharpening stones can be comprised of different materials. The synthetic materials used most often for sharpening stones are ceramics and diamond. Of course each material has its pros and cons.

## Natural sharpening stones

Natural sharpening stones are specific stones that were directly taken from a mountain, cut up into straight pieces and wrapped for shipment. Examples of natural sharpening stones are the [Ardennes coticule](kato://content/migrated_pageid_247) sharpening stones, [Skerper Arkansas](kato://content/migrated_pageid_303) stones and [Belgian Blue stones](kato://content/migrated_pageid_350).

Sharpening stone materials: which are the best?

Sharpening stone materials: which are the best?

Sharpening stone, whetstones and water stones: we often come across these terms. Also on our own website. But what are the differences between these terms? Or: are they even different at all?? We offer you an insight into this semantic discussion.


Why not start with ‘sharpening stones’. It is the collective term for all stones you use to sharpen knives, chisels, scissors, axes, in short everything with an edge. There are natural sharpening stones that are taken directly from nature, and artificial sharpening stones that are produced in a factory. The last group is often categorized based on the sharpening material used, or the country of origin. We sell, for instance, ceramic sharpening stones, diamond sharpening stones and Japanese sharpening stones.


## Whetstones


Another term often used for sharpening stones is whetstone. Both terms mean exactly the same. After all to whet is to sharpen! It is a rather dated term but one that is still used regularly.  

The materials used for these sharpening/whetstones are very diverse. Factory stones are mostly made from aluminium oxide, ceramics or diamond. The latter means: they have a diamond-coated sharpening layer, mounted to a steel or aluminium sheet. Natural sharpening stones, such as the [Ardennes Coticule](kato://content/migrated_pageid_247) stones consist of grenades, while stones from the American [Arkansas mountains](kato://content/migrated_pageid_303) have novaculite as an abrasive.


## So what are water stones?


The best sharpening stones (or whetstones) come from Japan. At least that is the generally accepted view, one we gladly endorse. After all, the Japanese are absolute experts when it comes to sharpening. Japanese sharpening stones are made from different materials and should generally be used in combination with water. This creates a ‘slurry’, because the water mixes with the loose sharpening particles. The advantage is that sharpening is easier and faster. In addition, the material that is removed immediately drains away because of the water. As such no metal particles can get caught in the stone which could cause scratches on the knife.


It is therefore not that surprising that Japanese sharpening stones are also often called water stones. Some water stones need to be submerged in water for them to fill up while others are ‘splash & go’. This means that only the surface of the stone needs to be wet and should remain wet during the sharpening process. For practically all Japanese sharpening stones applies that either one of these two methods of using water is necessary or strongly recommended.


The exception being Japanese diamond sharpening stones, such as the [Naniwa Diamond Stones](kato://content/migrated_pageid_902) collection. After all diamonds don’t wear out, which means that no particles are released while sharpening. There is therefore also no such thing as slurry when you sharpen your knives on diamond sharpening stones. You could, however, add a little water to the stone to make sharpening a little easier and less noisier.


## Are water stones exclusively Japanese?


Although they are often used together, ‘Japan’ and ‘water stone’ don’t necessarily have to go together. Not every Japanese sharpening stone is a water stone and not every water stone comes from Japan. Does this mean that non-water stones should be used ‘dry’. No, this is also not the case. Instead of water you could also add a couple drops of oil to the surface of some whetstones. This mostly applies to very hard natural sharpening stones. In general, however, the following applies: most common (non-diamond-coated) whetstones could be typified as water stones. 


The advantage of the (rare) oil stone is that they don’t wear out as quickly as the softer water stones. Water stones, however, remove a lot more material and are therefore a lot faster to work with. The difference between the two is caused by the binding agent that is used. The sharpening particles of a water stone are bound by softer material, the particles of an oil stone by harder material. Magnesium, for instance, which responds strongly to water but is still very strong. For that reason you should never submerge magnesium-bound sharpening stones.


## So the conclusion is…?


To conclude: sharpening stones and whetstones are the same and water stones are a frequently occurring sub-category of these stones. So don’t be confused by the logical suggestion that a whetstones should always be used in combination with water. That is not the case. In addition, water stones don’t always come from Japan.


When choosing a sharpening stone (or stones) you should always keep your goal in mind. Do you want to polish your knives? If you do you shouldn’t choose the diamond sharpening stone or an oil stone. In that case we recommend you always use a water stone with a high grain size. However, if you are also satisfied with less sharpness and want fast results diamond stones are a great option. Finally, do you only want to purchase one sharpening stone but use multiple ‘grits’? Why not opt for the Ardennes Coticule sharpening stone where the amount of slurry you create determines how fine you can sharpen.

Sharpening stone, whetstone, water stone: the meaning behind

Sharpening stone, whetstone, water stone: the meaning behind

Little cracks in your Naniwa sharpening stone: they do occasionally occur. Especially with the stones from the [Professional collection](kato://content/migrated_pageid_375) this is sometimes the case. We call these cracks hairline cracks. These small notches shouldn’t be confused with actual tears. They do not affect the quality of the sharpening stone. However, by properly maintaining your Naniwa Professional sharpening stone you can prevent these hairline cracks. Or at least limit them to a minimum.

It is important to realize that these sharpening stones do not need that much water. To improve the drainage of slurry and to make sure sharpening is a breeze, you can sprinkle them with water. Submerging the stone is neither wise nor useful: the stones do not absorb water.

## Magnesium as a binding agent

This is specifically relevant for the Professional collection (previously called Chosera). Compared to, for instance, the Super stones and the Diamond collection the Professional sharpening stones are not synthetic resin, but magnesium-bound. The main advantage of this binding agent is that the sharpening stones have more sharpening particles per surface unit. As a result, when you move your knife over such a sharpening stone, the edge will come into contact with a larger amount of sharpening particles (for the Professional collection this is aluminium oxide). The result: you sharpen faster and more accurately.

However, the disadvantage of magnesium is that it reacts quite strongly to water. For that reason we strongly advise against exposing magnesium bound sharpening stones to (a lot of) water. If you do decide to sharpen using water it is important to properly let the stone dry after use. First you need to rinse off the remaining slurry. Please note: rinse it off with a little bit of water, do not submerge the stone. Afterwards dry the stone with a microfiber cloth. This material is great because it easily absorbs water.

## Slowly let it dry

Now it is key to let the sharpening stone dry gradually. In this case there is no sense in rushing things. Put the stone on its side to make sure any remaining water can drip off. Make sure the stone won’t dry in the sun or on the heater. After all, the heat of the sun or heater will cause the surface to dry faster than the core of the stone. The tension that is created could cause small cracks in the sharpening layer. We call these cracks hairline cracks. You can reduce the chance of these cracks by wrapping the stone in the microfiber cloth you also used to dry off the stone. As a result the surface and the rest of the stone dry at approximately the same speed.

Is it a bad thing if you do happen do come across hairline cracks? No, it isn’t. A smooth sharpening stone will, of course, look better and water could seep in the cracks which means that it could take a little longer for the stone to dry. But considering the fact that you already need to be patient when it comes to drying the stone, this shouldn’t be an issue. The hairline cracks will – as mentioned before – not affect the sharpening results, which is also something Naniwa confirmed. However, if these cracks do affect your sharpening process you could, of course, always appeal to the guarantee Naniwa hands out with their stones.

Hairline cracks in your Naniwa Professional sharpening stone

Hairline cracks in your Naniwa Professional sharpening stone

Coarse and extra coarse sharpening stones are an important part of the sharpening process. A common mistake people make is to start sharpening with a stone with a too fine grain size. And yes, this happens faster than you'd think. By using too fine stones, it takes a lot of time to get the knife sharp again. Not very efficient. When you need to use a coarse sharpening stone depends, of course, on how you use your knives and the quality of your knives. A blade of a harder [type of steel](kato://content/migrated_topic_155) will remain sharp for a longer period of time than blades made from less hard types of steel.

Coarse sharpening stones

## Sharpness after use

After cutting, all the knives undergo the sharpness test again. In this test the ceramic knives perform considerably better than the steel knives. The test proves they do stay sharp for a longer amount of time. In using the knives we have not felt the difference in sharpness between ceramic and steel knives. This is because sharpness test only measures the sharpness of the blade itself. The geometry of a blade plays a big role in how the knife feels to the user. It is possible that a knife does not do extremely well in the sharpness test, but due to its geometry it can still cut really well. We also note that the ceramic knives are all thicker than the steel knives.

## Sharpening ceramic knives

The next step is sharpening the blades. The steel knives we sharpen on Naniwa Chosera stones up to grit size 5000\. For the ceramic knives we have used a battery charged diamond sharpener. Ceramic is such a hard material it can only be sharpened by diamond. It is difficult to get an even sharpening result with the diamond sharpener. The knives do get sharp but it takes quite some time and effort to get rid of the chipping on the blade. The machine also jams often, so we are not very positive about this means of sharpening.

The ceramic knives can be sent to the supplier to have a professional sharpen them. The box the knives are shipped in contains a voucher which can be exchanged for sharpening the knives. The problem remains you cannot use the knife for a certain amount of time and have to pay shipping costs. Just doing quick maintenance on your knife at home, with a sharpening rod or whetstone, is impossible. For steel kitchen knives there are many different possibilities to sharpen them at home or give them a quick touch-up.

## The twisting test

On the packaging of the ceramic knives it says they are unsuitable to twist and flex with. However, it is impossible to prevent some sideways pressure on the blade at all times. The twisting test also says something about how it can withstand falling so we have tested al the knives on this.

In this test a U-shaped holder is placed over the blade. The holder is twisted and we measure how much force we have to apply before the blade breaks. The Kyocera of 18 cm’s did pretty well with 0,33Nm. Even better than the thinly sharpened carbon steel knife we have tested, which broke with 0,30Nm. The Kyocera 13 cm knife did not do so well and breaks with 0,08Nm. When we tested a thin VG-10 knife of a big Japanese brand we could apply 7,75 times more pressure compared to its ceramic counterpart with 0,65Nm. The Wüsthof Classic knife we tested wins the test easily with a 1,34Nm.

The cheap ceramic knives do not come close to the Kyocera knives. One knife even broke when we put the holder on the blade to start the test. The difference between the cheap ceramic knives and Kyocera is not just the price and sharpness, but also lies in the quality of the material.

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