Advice on stones for polishing knifes

[abarbosa]

Hi!

I have a couple of carbon steel knifes that soon will need some thinning and polishing.

In terms of stones I currently have naniwa professional stones at the moment, 1000 and 3000.

I am looking to buy a couple of stones that would help me thinning and get kasumi polish on the laminated iron clad knifes.

I have been mainly considering Morihei, Kensho and Imanishi.

Can I get some advice on what stones do I need? At the moment since I don’t know better I am thinking of buying 1000-4000-6000 (or replace one of the previous with the 9000 karasu) from morihei and either buy the morihei 500 or buy other coarse stone like kensho 400, naniwa professional 400 or even shapton glass 500.

 

[ModRQC]

There's a lot of implications and personal preferences into polishing.

However you also mention thinning, and buying a 1000-4000-6000 set of any kind won't help you thinning.

400-500 grits stone would not be my first choice neither.

A Cerax 320 is no bad place to start, but its worlds apart from your Naniwas in terms of behavior. Can thin, can start a kasumi pretty well, easy to take up from there, and would give you an entirely different experience in stones. It's also dirt cheap.

Imanishi Arashiyama 1K is my favorite polisher. Might not be the ultimate Kasumi so not a stone you're likely to finish on, but it's a fantastic stone for polishing.

From there I've tried various alternatives. Favorites are Ouka/Cerax 3K or Morihei 4K. Kitayama 8K for +/- mirror core polish.

SG500 is nice to verify your bevels. What it tends to do is clean the steel entirely. Like any Kasumi hue you've obtained before is likely to be replaced by a clear polish. Makes it pretty easy for the stone that comes after. But I'll rather use SGs for minor polishing jobs when I want to mostly clear the core/clad line area trying to avoid scratches on the whole bevel.

 

[Pie]

Buy jnats

But actually. Consider it, as some low finisher/high mid grits are incredible for kasumi. The above is a more than adequate explanation for synthetics

 

[Benuser]

For the thinning I would choose the Shapton Glass 320. You may go lower but then you will need an intermediate stone before going to the NP1k. The NP400 is a fantastic stone but not for major thinning. You may use it for maintenance thinning as a part of a sharpening routine. The Naniwa grit sytem is a bit different from the Japanese standard JIS: the NP400 is more or less equivalent to a 600 stone.
As for polishing: not sure what you're expecting after a NP3k, which delivers a 4k end-result. For double-bevelled knives used in Western cuisine you hardly need any further refinement. Some finer stones do deliver a higher polish but not exactly a better edge. I believe it is the case with the highest grit Naniwa Super Stones, but i haven't used them myself. Other ones do deliver a somewhat finer edge with still some bite, but not the highest polish. In the latter case I would call the Shapton Pro 12k or the Naniwa Junpaku 8k 'Snow-white'. I use them for touching up my carbons. The Shapton is a bit easier in use than the Junpaku.

 

[Kiru]

Hey man,

For Kasumi finishing I reckon you will need to go lower than 500, you might want to consider sub 200 grit, I personally like the Suehiro LD 180.
After that, I second the Shapton glass 320, it's a great stone, cuts quick and stay flat for a while, one of my fav in this range, I reckon it's quite true to grit, alternatively the Suehiro SNE 320 is a good option too.
Maybe get the Shapton glass 500 or Naniwa pro 600 to bridge the gap between 320 and 1000.

After the Pro 3K, I would suggest the Arashiyama 6000, it's cheap, easy to use, very soft, gives "natural" kind of look on the soft steel and capable to mirror finish the hard steel

 

[ModRQC]

Three entirely different views of thinning polishing and whatever.

See what I meant by « lots of implications » and « personal prefs. I don’t think Kasumi has anything to do with how low you go which goes in hand with deeper scratches needed to be covered. I think it has to do with how low you go that gives a good basic hue and how easily dealt with therefore scratches are as you go up. But it really depends really on how you work it out on given stones for a given aim. And your aim will drive your questions and purchases as you go down THAT rabbit hole.

 

[Kiru]

Three entirely different views of thinning polishing and whatever.

See what I meant by « lots of implications » and « personal prefs. I don’t think Kasumi has anything to do with how low you go which goes in hand with deeper scratches needed to be covered. I think it has to do with how low you go that gives a good basic hue and how easily dealt with therefore scratches are as you go up. But it really depends really on how you work it out on given stones for a given aim. And your aim will drive your questions and purchases as you go down THAT rabbit hole.

You're very right regarding to "Kasumi does not have anything to do with how low you go"
The reason why I suggested the 180 is because I am assuming the knife has lots of low spot, which most of them have, however, I have also encountered a couple of them don't have crazy low spots, and I did start with the 500 grit stone

 

[abarbosa]

Thank you!

I forgot to mention that I have a atoma plate 140/400. I have indeed already encountered in some cheap knifes low spots which are indeed super annoying. Luckily the knife I want to work next shouldn’t have them since the maker already did kasumi on it with natural stones. Anyway I understand I may need a lower grit, but given that I mostly use my NP3K and rarely the NP1K I have some resistance to buy lower grits, so I would prefer to just buy one for now.

The Imanishi Arashiyama 1K seems like a good recommendation but unfortunately I can’t find it selling in Europe. Are there other good alternatives? I get since you didn’t recommend the Morihei 1000, that’s not a stone I should consider

The Cerax 320 is this one? SUEHIRO Cerax CR-400-G (#320) | SUEHIRO Whetstones | Hiomakivi.fi English

I also get that it may be important to have a hard stone to check bevels plus erase scratches which SG500 would be a good option. Or can I erase the scratches from thinning using the NP1K? I have to say that the NP1K was not such a great buy, it’s slow, creates a mess and in my polishing attempts so far on garbage steel it easily creates some shinny areas that look different, like more shinny which are hard to erase.

I am guessing I can’t stop at ouka 3000/morihei 4000. That’s why the suggestion of stones to make the core more reflective like the arashiyama/kitayama 6000/8000. I wonder if I can use some polishing compound instead? Like the ones to put on strops.

Thanks again for all the great advice so far, to summarize so far
1) I may need even lower grits than Cerax 320, mainly to deal with low spots on the knife;
2) Some stones may be useful to erase scratches and check bevels, like the SG500
3) Seems as well that I could try to improve my technique with my current stones and user them, even though my results so far with NP1K and NP3K are not good…
4) I don’t want to ignore the advice on JNats but I kind of have to since I don’t really understand them, don’t really know what to buy, so the cost just puts me away.
5) I need something just to make the core steel reflective and the arashiyama/kitayama 6000/8000 are good ones
6) NP400 I should exclude, and perhaps all the moriheis except the 4000

Great stuff! Keep the advice coming

 

[Benuser]

What kind of problems do you encounter when using the NP1k and NP3k? I'd indeed be surprised if it had anything to do with the stones.

 

[mrmoves92]

You shouldn’t have to get a different 1k stone. The Naniwa Pro 1k is great for kasumi at its grit. I have no experience with the Naniwa Pro 3k, and I have heard varying reviews about it, but I bet that it would work well before another stone at the very least. If you haven’t already, you should check out the grandiose synth kasumi thread on here. That should give you a better idea of what is possible with different stones. I especially like my Morihei 9k, JNS synthetic red Aoto, and the Naniwa Pro 1k, but I still haven’t tried a lot of stones.

 

[Heckel7302]

Have you tried polishing with the NP3K? I find it very difficult to get an even finish on it. It's so hard that I can't seem to avoid streaking. As an inexpensive option I've had good results following the NP3K with the King 6K. I also get good results from my permasoaked Gesshin 6K resinoid after a good slurry is worked up.

 

[abarbosa]

What kind of problems do you encounter when using the NP1k and NP3k? I'd indeed be surprised if it had anything to do with the stones.

NP1K leaves some shiny spots on the bevel and NP3K it’s really hard to keep mud being produced so the polishing becomes a bit inconsistent as well, those shiny spots show up as well. Of course it’s me the problem, not the stones. But at least I think these stones are not very beginner friendly for kasumi polish.

 

[Heckel7302]

NP1K leaves some shiny spots on the bevel and NP3K it’s really hard to keep mud being produced so the polishing becomes a bit inconsistent as well, those shiny spots show up as well. Of course it’s me the problem, not the stones. But at least I think these stones are not very beginner friendly for kasumi polish.

It's because the NP are super hard stones. They require a lot of finesse in pressure/slurry management, something I've not been able to achieve. Something softer will be a lot more forgiving. Really, think about trying the King 6k. Its super soft. It blows for edges IMO, but polish is pretty easy. And it's $25, not much of a gamble.

 

[Kawa]

Start very low.

If your knife is straight (no low or hight spots), you see soon enough and can go to the next step. You are not wasting anything, like on the edge.

There is a big pressurepoint (the pressure is spread over a large suface) so starting with 500 or higher takes a long time to evenly scratch the side of the blade.
Low gritt makes good scratches for a mid gritt stone to get 'grip' on.

 

[abarbosa]

It's because the NP are super hard stones. They require a lot of finesse in pressure/slurry management, something I've not been able to achieve. Something softer will be a lot more forgiving. Really, think about trying the King 6k. Its super soft. It blows for edges IMO, but polish is pretty easy. And it's $25, not much of a gamble.

That is indeed very tempting indeed. I am new in this world and I am still in denial… I am trying to avoid having a lot of stones, even if they are cheap. So I wouldn’t mind paying a higher price and have a stone good for edges and polishing. From previous posts in this forum that I read I thought the answer was Morihei, but I am now learning it’s much more complicated .

So perhaps I should just stop being in denial and pull the trigger on some of your suggestions and experiment.

I am already 100% convinced of the Cerax 320, which is easy since I don’t have any low grit. I just now need to decide from all your good feedback what else to pick. Thanks to all of you, this forum is amazing!

 

[ModRQC]

Morihei 4K wouldn’t bring you much good if you have NP3K. Imanishi Arashiyama 1K is very much the same than Bester 1200 if you can find it but since you have a NP1K then again… it’s really just that NPs are harder and more difficult to master and they really like a very flat bevel to work on or skills definitely need be involved. I like softer stones for polishing and keep hard stones for sharpening mostly.

Cerax 320 is a nice choice vs what you have. Not redundant and useful.

 

[abarbosa]

Morihei 4K wouldn’t bring you much good if you have NP3K. Imanishi Arashiyama 1K is very much the same than Bester 1200 if you can find it but since you have a NP1K then again… it’s really just that NPs are harder and more difficult to master and they really like a very flat bevel to work on or skills definitely need be involved. I like softer stones for polishing and keep hard stones for sharpening mostly.

Cerax 320 is a nice choice vs what you have. Not redundant and useful.

I see. Perhaps I should just get the cerax 320 and one finer like arashiyama 6000, kitayama 8000, morihei 9000 or king 6000. I may need to go lower depending on de state of the knife but I can perhaps postpone that.

That being said I can get a softer stone for polishing. JNS red aoto seems to be soft, are the Moriheis more on the soft side as well?

 

[milangravier]

Fondation work is key to have a good result when reaching finer stones. If the finish is not great at 1k, don't expect it to be better with you're final stone.
A good 200ish grit stone will speed up the process if you have a lot of grinding to do, a lot of low spots to solve. I mainly use Debado ld 180 grit. But I just discover a very nice 200 grit, harder than debado and grinding very well : imanishi arato 220 grit (the one on whetstone.fi, because there must be a lot of stone with that name).
Then a hard 400 grit is necessary : or a diamond plate, like naniwa diamond, or Naniwa pro 400.
After that, my progression is generally 1k naniwa pro, 2k naniwa pro, 3k naniwa super and one or fewer final stone, naturals for me.

Work crossing the scratches at same grit stone, especially on the coarse stones. So you will check what you're doing and see where stone doesn't touch.
It's very hard to find good coarse stones because when they are fast they generally are soft (cerax 320), and this is a lot of trouble for controlling your bevel shape. When they are hard, they sometimes just does'nt cut or you have to work with the mud made by atoma. Debado 180 and that imanishi 220 are quite sweet spot. If you feel you won't use those coarse stones often, you can also think about using an atoma 140 for thinning but that will make deep scratches (and if you don't know what you're doing it's a big risk), and you will kill the plate after maybe 3 or 4 knives thinning.

 

[abarbosa]

I think I got confused now. If I am doing kasumi polishing on a laminated wide bevel, at what stage to I want a soft stone and at what stage do I want hard stones

Not knowing anything, but just guessing, hard stones should be before the soft stones, so the foundation is flat. But maybe if the foundation is flat, using soft stones is just a way to make the life of the polisher easier, since they are more forgiving, but it’s not necessary. Does this make sense? I am just trying to draw some conclusions from the great advice I got from you so far.

For instance some of you suggest the Morihei 9000 karasu which is a hard stone, but the Kitayama/arashiyama are soft ones. So maybe it’s just a personal preference of what type of stones to use after setting a good foundation with hard stones.

 

[Pie]

Softer stones will help you with the actual polishing of the wide bevel and creating contrast. The mud produced allows grit to roll around creating the haze on the cladding. Softer stones are also more forgiving and generally speaking, less streaky when polishing.

Harder stones are useful for the foundational work, so you can be more precise when thinning and adjusting geometry.

Edit: I think you’re on the right track, but keep in mind polishing is a very personal thing. Once the basics are down, maybe you’ll have a hard stone you love to polish on. Conversely, maybe you find cerax 320 giving you a nice convex geometry that suits you.

FWIW, I find NP1k to be very versatile for polishing - it will provide anything from a slightly scratchy mirror on clean water to an almost scratch free, textured kasumi when used muddy. Think of it as a “choose your own adventure” starting point. Adjusting variables and managing mud will show the various capabilities of each stone.

 

[milangravier]

For fondation work (150/600 grit) : hardness of the stone depends of the type of metal you are working on. Hard stones help to give better control and precision (so I prefer them). But try a very hard whetstone on a very hard quenched steel and you'll quickly see it is sliding on it. So very hard steel will need a softer coarse stone to be grinded. Diamond stones are going to change a bit the game here as they can grind hard steel being hard too.

For 800/2k grit, I am not looking for a very hard stone as I just want to clean previous scratches and refine (I want a fast stone), but I am not shaping my geometry anymore, I just want to keep it as it is. If you don't mess around, NP 1K will be great for that.

For 3k/6k grit, I am generally working mostly hard steel there : Naniwa super stones are great for cleaning the hard steel. But NP 3k and 5k work great too with a little different finish at the end. If you work the hard steel, you can use a pretty soft stone as you will not make any trouble to the entire bevel anyway. Naniwa super and pro are pretty soft when you use them for polishing.
I got a Gesshin 4k, and that is a pretty hard fine stone... I don't use it really. It is good if you want a burnished finish and not a kasumi. Good thing is that you can check your geometry if you need to.
If you want a final synthetic stone in that grit range I am really not the best to advise.

For naturals : Mid grit (Aizu, Natsuya, Mikawa) are generally hard stones but being mid grit they are pretty easy to use. But as hard stone, if you use no mud with them you will start burnishing (light color finish).
For fine grits : Soft stone will be useful for cleaning 2k grits scratches on the iron + will make a nice hazy finish (scratchless finish) on the hard steel + will give you what we call kasumi finish : strong contrast between hard steel and soft steel. I would not say they are easier to use as having a proper clean plain kasumi is not always easy.
Hard stones will be used as finishers : they are not giving a hazy finish on the hard steel but miror so if you got previous scratches on hard steel it will be visible. On iron here they shines : they will not give strong contrast but they will bring out details and banding.

 

[Benuser]

Far beyond my knowledge. Just one warning: avoid the Chosera / NP5k. Softer than the others in the series, but a total lacking of feedback, both tactile as auditive. Removes any bite. Expensive.

 

[Better call Leo]

Far beyond my knowledge. Just one warning: avoid the Chosera / NP5k. Softer than the others in the series, but a total lacking of feedback, both tactile as auditive. Removes any bite. Expensive.

Totally agree. Tried Chosera 5k, absorb a lot of water and soft. It is very different to any other Chosera stones.

 

[milangravier]

Far beyond my knowledge. Just one warning: avoid the Chosera / NP5k. Softer than the others in the series, but a total lacking of feedback, both tactile as auditive. Removes any bite. Expensive.

Looks like the feedback on this stones are not shared and I often read bad review about it. I got no complain with mine. It is a bit soft but not much more compare to the 3k or 2k pro. Feedback is ok. Finish on iron is not my cup of tea (it's all dark) but finish on the hard steel is very nice and will be a good start before going to naturals

 

[abarbosa]

Thanks again for all the feedback.

I think I will give a try to:
- Cerax 320/Imanishi 220
- Shapton glass 500 (to clean the previous scratches and give me a clean and even canvas to work)
- Imanishi Arashiyama 1000 (I understand it may be redundant with the NP1k but I couldn't resist to try it out given the praise it gets for polishing)
- Morihei 4000 (this one I am buying just because I want to try a Morihei stone)
- Arashiyama 6000

I was a bit undecided between the Arashiyama 6000, the Morihei 6000 and the Morihei 9000 Karasu, but in the end I felt that 49 euros is much more reasonable for a stone that perhaps I will just use for bevel polishing. For edges I really like to stop at 3000/4000, I feel that the edge retention seriously degrades if I have a more polished edge, for instance if I use a strop loaded with a 5000 (green) compound after the NP3k, the edge gets so polished that after cutting 2/3 tomatoes on an Asahi cutting board the edge looses almost all the bite and start to struggle to cut tomatoes. Perhaps I should be doing some experiments with different sharpening angles or techniques since this sounds like an embarrassing edge retention but that a conversation perhaps for a different thread.

I am buying perhaps 2 more stones than I need, but I have more knifes than I need so at least I am being coherent.