A Few Observations, Thoughts & Ideas On Sharpening With Japanese Natural Waterstones

**thumbsucker** · 12th May 2015, 05:08 PM

Over the last six months NeilS and I have been exchanging emails on the topic of Japanese Tools, the following posts are a transcription and summation of those correspondences as they relate to sharpening with Japanese natural waterstones. Before I start I would like to thank NeilS for his generosity, both in regards to his knowledge, time and the loan of assorted Japanese natural waterstones from his private collection.

Warning

Japanese natural wasterstones are addictive, as So prominently warns all visitors:
"But I must warn you. These are highly addictive. View at your own risk..... (grin)"
Personally feel that Japanese naturals are a rabbit hole that most people should not venture into.
Because yes they are addictive, expensive, and time consuming.
And the more people use them the less there are for me. So bugger off folks.

I have been working with timber for almost ten years, in that time I have learned allot, however this is craft that demands continues exploration. It is easy to think that you have reached the summit only to find out how much further the away the peak truly is. Up to six months ago I used the Sigma Power range of ceramic waterstones for my sharpening and like many I was very happy with there performance. However as my exploration of Japanese tools has expanded it was possible inevitable that I would look into Japanese naturals.

I will be the first to admit that I am still learning, however I hope what information what I have garnered up this point maybe of value to others.

I started out with a few email to So japan-tools.com and NeilS. This lead me to acquiring two stones from Gadge, who sources some nice stones from around the Hunter Valley outside of Sydney. These stones acted as a taster for me, allowing me to gain a feeling for natural stones. I will not go into details of these stones as I wish to focus on the Japanese Naturals. Eventually I manned up and purchasing this Ohira Namito from So via his shopping cart. This is my review posted on So's websites the Ohiro Namito:

This was my first plunge into Japanese naturals, so I jumped in head first. Wanting a finishing stone in the #20000 grit range that could achieve the ultimate in sharpness for my Japanese woodworking tools and with a preference for harder stones So recommended this Ohira Namito. The stone is a massive, a literal brick. I have no expectation that I will ever wear out the stone in my lifetime. While it was described as having a grey colour it has a hue of green to it. The Ohira Namito is super hard and super fine. This stone needs virtually no water and definitely no soaking, I just wash it under the tap for a second, then the wipe away most of the water. When the stone becomes a little dry I use a atomizer spray bottle to just mist the stone, just a little. You definitely need a diamond plate or nagura to raise a slurry. Even then the stone is not muddy in the slightest. This stone even after extensive use remains flat. When the stone arrived it had slight wobble to it, due to an uneven bottom. I affixed a ceder board as a base to stabilise it while sharpening. The Ohira Namito gives a beautiful hazy finish, with a pure homogenise bevel, devoid of errant scratches, confirming the uniformity of the abrasive particles in this stone. The feel of the stone is supper smooth, with little to no stiction, yet the stone is capable of removing material aggressively.

I would add to the above review the following: I have had a periodic problem with the Ohira, as I travel backwards and forwards on the diagonal the chisel chatters no matter what I do. I try more pressure and less, changes angle of travel. Neil suggested less pressure and or more water. Adding more water worked in part, however it had the down side of washing away my slurry. I needed to flood the stone and then using the diamond plate to emulsify the slurry and water. However reducing the pressure was more beneficial. I found that I was almost lifting the blade off the stone, lifting up my shoulders so that the tool just made the slightest contact with the stone.

Ohira_NamitoA.jpg

As part of my education Neil lent me the following stones: The reason for the loan was to broaden my experience of naturals as well as providing me with coursers grit stones. As the jump from a #2000 synthetic to a #20000 Ohiro Namito was to large and was hindering the full utilisation of the Ohiro Namito.

Aoto Tamba

Neils Comments

Aoto from Tamba, mined by Tanaka family. Aoto are typically used before nakatoishi stones, so pre-nakatogi. A very soft muddy stone, so don't spare the diamond plating to keep it flat. This stone starts at about 2k and works down to 4k grit. Use after 1k synthetic or, if you like, after the 2k synthetic as I do. It will leave an abrasive pattern close to 4k, but without the deep scratches that are left by the synthetics. I tend to resharpen more often so don't need to go back to this stone unless I have to resort to a 1k or 2k synthethic to rework the blade.

Thumbsuckers Comments

The stone is soft but not to soft I found that I did not need to raise a slurry with the Atoma. Out of the stones this is one stone that I would keep it is good for removing the synthetic scratches. I found that I was prone to dig in with the side edge of the chisel as I travel at 45º across the stone. A problem I do not have on the harder stones.

IMG_4524.jpg

Takao Kiita

NeilS Comments

Takao, Kiita (ie light yellow) on the soft side (3.5/5) with grit going down to about #18k. A smoother stone than the Hakka. Used by some as a awasedo (finishing) stone. Will leave a fine hazy finish ready for a fine misty finish off your Ohira.

Thumbsuckers Comments

This stone has a smell to it a real earthy scent with a hint petrol. Its the first stone I noticed a smell. The stone feeling changes on the section that is grey, it feels harder and smoother.

IMG_4525.jpg

Hishiboshi Karasu

NeilS Comments

The Hishiboshi Karasu, a natural-synthetic #9k hybrid stone. I did a review of it here. I included it so you can have a play with something different yet again. It's very soft but also very smooth. I see it as a halfway option for those who are not ready to make the full leap to the naturals

Thumbsuckers Comments

This is a stone I wanted to like, I tried to use going from the Sigma #2000 to the Sigma #6000 to the Hishiboshi Karasu to the Ohira. While it did a good job of removing the synthetic scratches I was not as good as going from the Aoto Tamba to the Takao Kiita to the Ohira. I also feel that its closer to a synthetic then to a natural. It leaves a very high shine like a synthetic rather then a more frosty finish I have come to prefer.

IMG_4527.jpg

Okuda

NeilS Comments

A green Okuda from the Tomae strata. A razor size stone. Softer than the hardest Okuda, but much harder than the other stones above. Also included is some tomo nagura from the same stone layer to help raise a little mud. This is a very fine grit in a slightly softer stone than usually available in very fine grits. I use it for micro-bevels, which I use with some of my knives. I include it so you can experience an awasedo stone other than your Ohira. We don't get many opportunities to play with other stones.

Thumbsuckers Comments

This stone is gives a finish very much like my Ohira. I will say that I like the nagura, it is much better then a diamond plate. The diamond plate generates a large amount of slurry in comparison to the nagura with Okuda from the Tomae strata the nagura just raises enough slurry to abrade. A thin film, instead a sea of mud. I plan to get a nagura for my Ohira Namito.

IMG_4528.jpg

Hakka Namito

NeilS also lent me a Hakka, Namito strata. Unfortunately I had a misshape with this stone:

I have some regrettable news - Neil please accept my apologies - the Hakka Namito split along its length. I had just wetted down the stone to try it out for first time, worked up a little slurry with the diamond plate, after 10 seconds of use with the 24mm chisel I noticed a fine line on the surface on the stone. I stopped, I picked up the stone at the corner and the stone came apart into two half’s. Neil since I broke it I am more then willing to buy it from you. Again please accept my deepest apology. I have attached some photos.

Like the Aoto, the Hakka is used on the side of the strata, the way I suggested you use Garry's stone. Most naturals are used on a face that runs parallel to the strata layers. I have had naturals start to separate along the strata lines in stones that are used parallel to the strata. I have a method for rescuing and keeping those stones going. I can experiment to see if it works with the Hakka when it comes back. BTW, what did you have under the stone when it went?

broken stone 01.jpg

Neil was kind enough not to kill me.

A2 Tool Steel on Japanese Naturals

Out of interest Neil suggested I try using one of my A2 blades on his softer Japanese naturals, as I found the the very hard Ohiro Namito did not deal with the A2 very well. The softer stones did a nice job of the A2 however the Ohira struggled a to give me a good finish. I think Neils explanation of why softer stones are better for knives applies for the A2 tool steel blades.

NeilS

Harder stones stay flatter and help produce flatter bevels. As the surface area to be sharpened is relatively small on chisels and plane blades, the slower sharpening usually associated with harder stones is not such as issue.

Knives have a much, much, larger area to be sharpened. The average combined length of a two bevel knife is over 350mm and the width of the higane on some of my knives is up to 7mm (because the 'included angle' is as low as 10deg). That is a massive area of hard steel to sharpen. Such fine edges are also prone to micro-chipping, so require a lot of reworking to re-establish a good edge when that happens.

They say 'hard steel needs a soft stone and a soft steel a hard stone'. That's just another way of saying use a stone that readily lets its particles go to expose new sharp grit to abrade the harder steel. Not all soft stones are aggressive or all hard stones slow, but you pay a big premium for hard stones that are also aggressive. As you found, the soft Aoto removes the metal quickly and is relatively economical.

**thumbsucker** · 12th May 2015, 05:23 PM

I decided to create photo log of the sharpening of a kanna blade using a few naturals. I hope that it will serve to illustrate there properties and act as a justification for some of my conclusion. I will start with the following statement:A microscope is the greatest single tool for sharpening! No matter what abrasive medium you prefer. A blade may feel sharp, but the microscope never lies. While an edge may look perfect for the lack of a better word the microscope allows one to truly understand what is going on at the cutting edge. An edge can be uneven, chipped or have a dozen other defects, not visible to the human eye. In the past I have experienced an edge that looked sharped, however simple did not perform as would expect it to have. I believe a microscope would have quickly revealed the problem. If nothing else I highly recommend that everyone should go out and purchase a microscope. I purchased a little number from eBay for $30. It magnifies from 60 to 100 times and has a nice focus. IMG_4519.jpgNeil wrote The scope is

especially while learning what is really happening to the edge. Observing closely what happens with the blade in use then adds to your understanding.I still check with the scope to see what is happening when I start to use a stone I have not used before. And, with my regular stones, if I'm not happy with the cut I'm getting after sharpening I will check with the scope to see what is the cause.Also, when rehabbing a blade I check to see if I have reestablished all of the edge before moving off the coarse stone. Feeling the burr tells you when to start looking with the scope.In my experience a diamond plate and a scope are indispensable.

This video nicely illustrates why a microscope has become an essential part of my sharpening routine.

The kanna blade is a 70mm wide blade. I used the Veritas honing guide to form a 35º bevel using a #2000 Sigma. The bevel is so high because I have found this blade to be prone to chipping. I also tapped out the ura. In short decided to rework this blade from the start.

IMG_4553.jpg IMG_4554.jpg

The bevel showed deep scratches to the naked eye. Under the scope they looked like deep fissures. While the right corner shows remnants from the diamond plate it was superficial and I was not concerned about them as I knew I would remove them quickly. The #2000 Sigma gave the blade a distinct shine.This photo shows the ura after 40 strokes on the Aoto Tamba. The blade has taken on a nice frosty appearance and the synthetic scratches have been removed.

IMG_4555.jpg

The bevel looks good to the eye however a 100x magnification deep scratches and a large chip can be seen. A full width burr is detectable. This bring me to my second observation. Turning a burr is a poor indicator to the state of an edge. Here a nice burr has been turned however the edge is chipped and errant scratches abound. I removed the burr at this point on the Aoto Tamba. The second photo shows the Aoto Tamba while it is soft it is not overly muddy.

IMG_4557.jpg

After 60 more stroke on the Aoto Tamba I have turned another good burr and removed most of the deep scratches from the #2000 Sigma. However the microscope reveals that while a burr has been turned the scratch patter is not uniform all the way to the edge. Also while the bevel has a dark grey colour, there are noticeable white scratches running parallel to the edge. Deeper scratches can be seen at the leading edge. Here is another observation, the finger nail test is often lauded as proof of a sharp edge. However here is a tool that is essentially blunt but I can take shaving from my finger nail.

IMG_4558.jpg

I continued working the blade on the Aoto Tamba, until the edge was uniform all the way to the edge and all errant white scratches had been removed. I then started on the Takao Kiita. Turned a burr after 40 strokes. Here the edge looks perfect and shaves my fingernail with ease. However at this point I became aware of white lines running perpendicular to the edge. I believe these were from the synthetic. It took another 100 strokes to remove the last errant scratches.

IMG_4562.jpg IMG_4561.jpg

This photo show how soft and muddy the Aoto Tamba is:

IMG_4567.jpg

Now I moved on to the Ohiro Namito. This is what the back looked like after 60 strokes. Nice light frosty grey colour however the scope reveals some errant scratches. A 100 more strokes makes the back perfect under the scope.

IMG_4569.jpg

The bevel took 60 strokes to achieve a fine uniform appearance under the scope using the Ohiro Namito. The following photos show the atomiser that I have found much better then a water bottle for misting up a stone. It adds enough water for lubrication but does not wash away the valuable slurry, the second photo show how the slurry breaks down into finer grit size. An important tip I picked up from So and Neil was that you need to start with a fair amount of downward pressure when you start using a fine stone, then as you break down the slurry, to slowly ease off on the pressure until at the very end using on the lightest possible touch.

IMG_4570.jpg IMG_4573.jpg

This is what the bevel looks like in the end. Note that the deep scratches from the diamond plate are gone. I might mention another tip I got from Neil. On the finest stone I would work harden the edge by repeated strokes of the bevel and then the back. I do a count down 10 strokes on the bevel 10 strokes on the back, 8 strokes on the bevel 8 strokes on the back, 6 strokes on the bevel 6 strokes on the back, 4 strokes on the bevel 4 strokes on the back, 2 strokes on the bevel 2 strokes on the back, and then I will do 1 stroke on the bevel 1 stroke on the back, a few times. I find that this process refines the edge greatly through a process of work hardening and ensures the total removal of the burr. While you cannot feel the burr you can often see a white hallo under the scope.

IMG_4574.jpg IMG_4576.jpg

Next I fitted the blade into the dai, this is a tool to which I am still learning how to setup and adjust, so I am not able to get a shaving worthy of entry into KEZUROU-KAI, however I can muster a pass. However I hope that the following photos do illustrate that the edge, was uniform by taking full width shaving, without gaps or tears in the shaving which would be indicative of chips or defects in the blade.

IMG_4579.jpg IMG_4582.jpg

I hope that these posts are useful and informative.

**rmihai** · 13th May 2015, 11:52 AM

Great. Thank you.

Originally Posted by thumbsucker

I decided to create photo log of the sharpening of a kanna blade using a few naturals. I hope that it will serve to illustrate there properties and act as a justification for some of my conclusion. I will start with the following statement:A microscope is the greatest single tool for sharpening! No matter what abrasive medium you prefer. A blade may feel sharp, but the microscope never lies. While an edge may look perfect for the lack of a better word the microscope allows one to truly understand what is going on at the cutting edge. An edge can be uneven, chipped or have a dozen other defects, not visible to the human eye. In the past I have experienced an edge that looked sharped, however simple did not perform as would expect it to have. I believe a microscope would have quickly revealed the problem. If nothing else I highly recommend that everyone should go out and purchase a microscope. I purchased a little number from eBay for $30. It magnifies from 60 to 100 times and has a nice focus. IMG_4519.jpgNeil wrote The scope is This video nicely illustrates why a microscope has become an essential part of my sharpening routine.

The kanna blade is a 70mm wide blade. I used the Veritas honing guide to form a 35º bevel using a #2000 Sigma. The bevel is so high because I have found this blade to be prone to chipping. I also tapped out the ura. In short decided to rework this blade from the start.

IMG_4553.jpg IMG_4554.jpg

The bevel showed deep scratches to the naked eye. Under the scope they looked like deep fissures. While the right corner shows remnants from the diamond plate it was superficial and I was not concerned about them as I knew I would remove them quickly. The #2000 Sigma gave the blade a distinct shine.This photo shows the ura after 40 strokes on the Aoto Tamba. The blade has taken on a nice frosty appearance and the synthetic scratches have been removed.

IMG_4555.jpg

The bevel looks good to the eye however a 100x magnification deep scratches and a large chip can be seen. A full width burr is detectable. This bring me to my second observation. Turning a burr is a poor indicator to the state of an edge. Here a nice burr has been turned however the edge is chipped and errant scratches abound. I removed the burr at this point on the Aoto Tamba. The second photo shows the Aoto Tamba while it is soft it is not overly muddy.

IMG_4557.jpg

After 60 more stroke on the Aoto Tamba I have turned another good burr and removed most of the deep scratches from the #2000 Sigma. However the microscope reveals that while a burr has been turned the scratch patter is not uniform all the way to the edge. Also while the bevel has a dark grey colour, there are noticeable white scratches running parallel to the edge. Deeper scratches can be seen at the leading edge. Here is another observation, the finger nail test is often lauded as proof of a sharp edge. However here is a tool that is essentially blunt but I can take shaving from my finger nail.

IMG_4558.jpg

I continued working the blade on the Aoto Tamba, until the edge was uniform all the way to the edge and all errant white scratches had been removed. I then started on the Takao Kiita. Turned a burr after 40 strokes. Here the edge looks perfect and shaves my fingernail with ease. However at this point I became aware of white lines running perpendicular to the edge. I believe these were from the synthetic. It took another 100 strokes to remove the last errant scratches.

IMG_4562.jpg IMG_4561.jpg

This photo show how soft and muddy the Aoto Tamba is:

IMG_4567.jpg

Now I moved on to the Ohiro Namito. This is what the back looked like after 60 strokes. Nice light frosty grey colour however the scope reveals some errant scratches. A 100 more strokes makes the back perfect under the scope.

IMG_4569.jpg

The bevel took 60 strokes to achieve a fine uniform appearance under the scope using the Ohiro Namito. The following photos show the atomiser that I have found much better then a water bottle for misting up a stone. It adds enough water for lubrication but does not wash away the valuable slurry, the second photo show how the slurry breaks down into finer grit size. An important tip I picked up from So and Neil was that you need to start with a fair amount of downward pressure when you start using a fine stone, then as you break down the slurry, to slowly ease off on the pressure until at the very end using on the lightest possible touch.

IMG_4570.jpg IMG_4573.jpg

This is what the bevel looks like in the end. Note that the deep scratches from the diamond plate are gone. I might mention another tip I got from Neil. On the finest stone I would work harden the edge by repeated strokes of the bevel and then the back. I do a count down 10 strokes on the bevel 10 strokes on the back, 8 strokes on the bevel 8 strokes on the back, 6 strokes on the bevel 6 strokes on the back, 4 strokes on the bevel 4 strokes on the back, 2 strokes on the bevel 2 strokes on the back, and then I will do 1 stroke on the bevel 1 stroke on the back, a few times. I find that this process refines the edge greatly through a process of work hardening and ensures the total removal of the burr. While you cannot feel the burr you can often see a white hallo under the scope.

IMG_4574.jpg IMG_4576.jpg

Next I fitted the blade into the dai, this is a tool to which I am still learning how to setup and adjust, so I am not able to get a shaving worthy of entry into KEZUROU-KAI, however I can muster a pass. However I hope that the following photos do illustrate that the edge, was uniform by taking full width shaving, without gaps or tears in the shaving which would be indicative of chips or defects in the blade.

IMG_4579.jpg IMG_4582.jpg

I hope that these posts are useful and informative.

**NeilS** · 13th May 2015, 01:03 PM

A good run down there on those J-nats, Thumbsucker.

It looks like you are not about to go back to just the synthetics any time soon.

Perhaps a digital scope that captures mag shots will be added to the long list of other things to get when funds permit.

Originally Posted by thumbsucker

This photo show how soft and muddy the Aoto Tamba is:

IMG_4567.jpg

I think that one is the Takao. Yes, that is one very muddy stone.

Stay sharp!

Neil

**thumbsucker** · 13th May 2015, 01:39 PM

Neil - As far as Japanese tools go, I much prefer the jnat.

Yes a scope with camera would be nice. In time.

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