# Do I need a polishing stone?



## agp (Oct 14, 2020)

Currently using a Naniwa 1k and 3k for sharpening my knives - do I need a higher grit polishing stone? Do those really make a big difference aside from party tricks like parallel slicing tomatoes/grapes?


----------



## Qapla' (Oct 14, 2020)

Are you using any single-bevel knives?


----------



## Benuser (Oct 14, 2020)

Depends on the kind of steel your knives are made of, and whether you can achieve a complete deburring with the 3k.


----------



## agp (Oct 14, 2020)

No single bevel. I have some blue and some stainless. I don't use the stainless much though.


----------



## Benuser (Oct 14, 2020)

The Naniwa grit system does not correspond exactly to the usual Japanese standard JIS. A 3k delivers a 4k end result. With double-bevelled knives in Western cuisine with much board contact no reason to go any further. You may, but there's no need.


----------



## ref (Oct 14, 2020)

agp said:


> Currently using a Naniwa 1k and 3k for sharpening my knives - do I need a higher grit polishing stone? Do those really make a big difference aside from party tricks like parallel slicing tomatoes/grapes?



You can do those tricks with a 300 grit edge (and in fact, coarse edges can be better for things like tomatoes).

Higher grits do not give you increased sharpness, but they do refine the edge, which means they cut things smoother (but not necessarily easier). For almost all kitchen tasks, you don't need to cut things smoother, you need enough bite to dig in to them in the first place (ever tried to slice a slightly old wrinkly pepper?). There are some things where you may want a higher grit edge, slicing fish for example.


----------



## Alder26 (Oct 14, 2020)

If you have a naniwa 3k, you already have what many consider the king of all kitchen edges. Lots of bite for veggies, plenty of polish for almost all slicing tasks. It does everything well. 
Now if you feel the need to experiment with higher grit finishes, I would advise that you buy something like a Morihei hishiboshi 9k or a shapton pro 12k, or similarly of _super_ high grit. I say this because buying a 6k stone probably isn't going to get you a remarkably different feel than a Naniwa 3k. Or there is always......natural stones.....


----------



## JDC (Oct 14, 2020)

king g-1 8000 leaves a lot of teeth following 1000, great stone for the edge


----------



## inferno (Oct 15, 2020)

agp said:


> Currently using a Naniwa 1k and 3k for sharpening my knives - do I need a higher grit polishing stone? Do those really make a big difference aside from party tricks like parallel slicing tomatoes/grapes?



its nice to have a high grit stone imo. its another tool in the arsenal. sooner or later you gonna need it.
the finer the stone gets the sharper the edge gets, well potentially. its up to you and the steel you have. for carbon 12-15k no problem.

i like the shapton pro 12k. the 8k glass gray hc is nice. and so is the 6k.
8k shapton pro is probably my best allround high grit stone.
superstone 12k is a very good polisher.
i heard good things about the 16k glass.

i also have the imanishi 10k and cerax 8k but i dont actually sharpen on them. only for blade sides/kasumi, since the other stones are vastly superior for sharpening.


----------



## dafox (Oct 15, 2020)

inferno said:


> its nice to have a high grit stone imo. its another tool in the arsenal. sooner or later you gonna need it.
> the finer the stone gets the sharper the edge gets, well potentially. its up to you and the steel you have. for carbon 12-15k no problem.
> 
> i like the shapton pro 12k. the 8k glass gray hc is nice. and so is the 6k.
> ...


What do you the finer stones for?


----------



## inferno (Oct 15, 2020)

what do you mean?


----------



## Qapla' (Oct 15, 2020)

inferno said:


> what do you mean?


I think he missed the word "use", and meant what sorts of knives do you use the finer stones among those you mentioned for.


----------



## dafox (Oct 15, 2020)

inferno said:


> what do you mean?


Yes, what do you use the finer stones for?


----------



## inferno (Oct 15, 2020)

sharpening edges - pro8k, pro12k, glass6k gray.
polishing monos - the above 3 plus the ss 12k, imanishi 10k, cerax 8k.
kasumi contrast - glass 6k gray, cerax, imanishi.

different horses for different courses.


----------



## Qapla' (Oct 15, 2020)

inferno said:


> ...for carbon 12-15k no problem.


Which 15k stone did you use? One doesn't hear of those too often.


----------



## jacko9 (Oct 15, 2020)

The question I have is as you go up in grid sizes do you risk rounding over the bevel? I mean you set the bevel at a lower grit and then refine the edge as you progress up in grits at what point do you risk accumulated bevel angle errors and get a convex sharpening angle at the edge?

As an experience when sharpening wood chisels with the Veritas Mk II guide the higher I went in grit the less the chisel cut with ease? The best chisel edge for cutting was a hollow grind with a hand crank wheel and a edge to heal polish.


----------



## Kawa (Oct 16, 2020)

Just going up in gritt doesnt make your edge round off?
Atleast, when you sharpen correctly.
You should hit the exact same angle as on you lower gritts, therefore keeping that one bevel you did aim for.

But,
We are no robots, so I think I understand where the question comes from...
Make a mistake at lower gritt (too high angle, aka unintented microbevel) and you 'round off' you edge. But it is so fast, that it looks like a wrongly put, unintended 2nd bevel.
Easy restored at this gritt though.

When you hit your edge with a high gritt stone at a too high angle, you probably f#ck up your edge the same as with the coarse stone, but the result/error is way smaller: the microbevel is so small it feels like a rounded edge??? while in fact its the same wronly applied 2nd bevel as with your coarse stone.

It's harder too remove a tiny error from a high gritt stone, with a high gritt stone, then to remove (or reset) an error in the early stages....
I think that's why people say, the more stones and the higher the finish, the more room for error.

I think this is one of the hardest part of sharpening: keep the same angle and therefor that exact one bevel you aim for, during all the stone prgression. It's sooooo easy to hit that edge too high for only a few strokes.... Do you continue, or go back a gritt....


----------



## inferno (Oct 16, 2020)

Qapla' said:


> Which 15k stone did you use? One doesn't hear of those too often.



the shapton 12k used to be labelled the 15k in japan before, it might still be i dont know.
other than that the shapton UF is extremely fine, at least 15k, true mirror polish. unlike all my other stones.


----------



## JDC (Oct 16, 2020)

inferno said:


> the shapton 12k used to be labelled the 15k in japan before, it might still be i dont know.
> other than that the shapton UF is extremely fine, at least 15k, true mirror polish. unlike all my other stones.


Probably you meant Spyderco UF? Curious if it loads up or leaves busy scratches at certain light angle.


----------



## inferno (Oct 16, 2020)

if anyone is considering buying a high grit stone. you should ask yourself: what do i want it to do? soaker or s&g? soft or hard etc.

shapton pro 12k - s&g, hard, no slurry, no contrast, works with powder steel, mirror like finish 7-8/10
shapton pro 8k - s&g, hard, no slurry, no contrast, works with powder steel, shiny but no real mirror like 6-7/10
glass gray 6k - s&g, hard, no slurry, fairly good contrast, works with powder steel, almost true mirror like 8-9/10
superstone 12k - s&g, hard but softer than pro, no slurry, no contrast, works slow on powder steel, almost true mirror like 9-9,5/10, slower than 12k pro
cerax 8k - long soaker/1 week dry, soft, slurry, highest contrast, probably ok on powder, hazy finish no mirror 5-6/10
imanishi 10k short soaker/1 day dry, soft, slurry, medium/low but good contrast, probably no good for powder steels, very consistent hazy finish 6-7/10

the score is how much of a mirror polish they produce. 

also when you get up to like 8k and above the numbers are pretty much meaningless. 10k, 15k or 30k they could produce the exact same finish. 
my 6k gray glass produces a finish that is almost as shiny and mirrory as the ss12k. but its much faster when sharpening. and the soakers will never ever produce any mirror finish at all. its fine, but its hazy.


----------



## inferno (Oct 16, 2020)

JDC said:


> Probably you meant Spyderco UF? Curious if it loads up or leaves busy scratches at certain light angle.



yes of course!

the UF loads up very fast, and its hard to clean it to keep it cutting. it leaves a true mirror finish, as mirror as it gets. 
i only use it on razors because it would be to slow on knives. and its also rock hard so its very unpleasant to sharpen on. its stops cutting if you put water on it. it has hundreds of stray particles from the factory.


----------



## Ruso (Oct 16, 2020)

You do. Finer edge stays sharper longer.


----------



## DrEriksson (Oct 16, 2020)

This is not about what you need. That logic will just save you a lot of money. 

Jokes aside. I finish my knives on Shapton glass 3000. I use 8000 for knives dedicated to meat. Works great for me. Question is what works for you, and if you think that it’s fun to mess about with knives.


----------



## DrEriksson (Oct 16, 2020)

Ruso said:


> You do. Finer edge stays sharper longer.



Have you seen any tests? I’ve only seen Outdoors55 test on EDC knife and with cardboard.


----------



## mpier (Oct 16, 2020)

IMO for double edge blades you do not need a polishing stone for normal day to day kitchen use. But that doesn’t mean I won’t use one just to look at a beautiful edge when it’s done but in general it is just a waist of time when it comes to standard kitchen use. But I would and do use it for most of my single bevel knives. I would suggest getting one as stated above just to add to the arsenal.


----------



## Ruso (Oct 16, 2020)

DrEriksson said:


> Have you seen any tests? I’ve only seen Outdoors55 test on EDC knife and with cardboard.



I did not see any scientific test with controlled environments or one specialized on kitchen knifes.
I’ve seen several test on youtube on this topic, including the video you’ve posted. However they should translate well to kitchen knives and food prep.

This are also my personal observations and somewhat a general knowledge. All of this does not make it true per se, but its a good basis.


----------



## DrEriksson (Oct 16, 2020)

Ruso said:


> I did not see any scientific test with controlled environments or one specialized on kitchen knifes.
> I’ve seen several test on youtube on this topic, including the video you’ve posted. However they should translate well to kitchen knives and food prep.
> 
> This are also my personal observations and somewhat a general knowledge. All of this does not make it true per se, but its a good basis.



Thanks. Not doubting your experience or saying that you’re wrong. This is just the kind of thing that intrigues me. Cedrik & Ada has been doing a lot of tests, but focus on EDC blades. Otherwise Ryky did the rope cut thing, but that was only on a knife basis, if I’m not mistaken. (Please, no flame about Ryky. I only mentioned the fact that he did tests.)


----------



## mpier (Oct 16, 2020)

Ruso said:


> You do. Finer edge stays sharper longer.


So I am going to respectfully disagree with you on that, coming just from an engineering point of view. When you have a “ toothy” edge you have a more structured edge, meaning the highs and lows of your grind add a structural rigidity to your edge it will last longer but may not get quite as sharp. When you go to a higher grit and start removing that structure you lose edge retention, for me that is just straight up engineering and geometry.


----------



## inferno (Oct 16, 2020)

actually a mirror polished edge will last longer at least on non ultra high carbide supersteels it seems.
s30v 330 vs 275 cuts. 
aus-8 20% more
3v 290 vs 240


----------



## Benuser (Oct 17, 2020)

Ruso said:


> You do. Finer edge stays sharper longer.


The 4k edge a Naniwa 3k delivers is already a very fine one.


----------



## kayman67 (Oct 17, 2020)

Qapla' said:


> Which 15k stone did you use? One doesn't hear of those too often.


Shapton Pro 12 was 15 in the past, as said above. 2:1 stone 
There are some 15-16k stones out there. Not a very usual grit, though. 

Anyway, higher grits are about skill before the grits themselves. Some stones might make it easier, some not so much. This doesn't make them better as in best possible results, but some results are better than no results or worse. And at some point you choose even without knowing. I do like some stones better than others, but that might be just me.
One of the most unusual combos is the Sigma 1200 + 13000. Seems so unreasonable to make such a huge jump and for some purposes it is, but for some reason, the 13k really improves edge retention even with more demanding alloys (like ZDP-189 or HAP40). I was quite amazed especially with ZDP-189. I always wondered how such a combo came into existence (since Sigma has 6000 and 10000 that would have been a more convenient choice maybe). 



mpier said:


> So I am going to respectfully disagree with you on that, coming just from an engineering point of view. When you have a “ toothy” edge you have a more structured edge, meaning the highs and lows of your grind add a structural rigidity to your edge it will last longer but may not get quite as sharp. When you go to a higher grit and start removing that structure you lose edge retention, for me that is just straight up engineering and geometry.



Not really true. Was proven already that micro fractures at apex level will dull the edge faster (even maintenance involved). There is something that concerned some alloys where the structure is so much more resilient, that would actually benefit, but rarely, if at all, common with kitchen knives.


----------



## M1k3 (Oct 17, 2020)

kayman67 said:


> Shapton Pro 12 was 15 in the past, as said above. 2:1 stone
> There are some 15-16k stones out there. Not a very usual grit, though.
> 
> Anyway, higher grits are about skill before the grits themselves. Some stones might make it easier, some not so much. This doesn't make them better as in best possible results, but some results are better than no results or worse. And at some point you choose even without knowing. I do like some stones better than others, but that might be just me.
> ...


Is the Sigma 13k one of the SiC stones? I've heard a few if them are SiC, the rest AlOx?


----------



## inferno (Oct 17, 2020)

as far as i know only the green 240 and the black 1k are SiC.

stefan wolf on the tube has a few high grit sic stones. look it up on youtube. but they appear to be tool stones.


----------



## kayman67 (Oct 17, 2020)

1000 is also SiC. I'm not entirely sure about 1200, but it's really fast with ZDP-189.


----------



## kayman67 (Oct 17, 2020)

1200 seems to be Aluminum Oxide, but Jende says it removes matrix steel and carbides. That's pretty much like coarse SiC behaviour and would explain why I found it to be so efficient.


----------



## inferno (Oct 18, 2020)

a 1k stone is so coarse and if the binder behaves in a certain way and the abrasives are shaped a certain way i guess it could scoop out lots of steel even if its an alox stone. i guess a good 1k is a good 1k no matter what steel and what abrasive is used.
i really haven't found a 1k yet that was really slow even on high alloyed steel.


----------



## kayman67 (Oct 18, 2020)

The most interesting 1000 stone I came across, was from Chroma a few years ago. I don't know who made it as no other manufacturer I tried had something similar. This was a soaking stone, very very hard, very very fast, but also had the feedback of a much finer stone (more like Chosera 3000).

Sigma 1000 looked to me as being SiC. Searching a bit, looks like it is.


----------



## zizirex (Oct 18, 2020)

kayman67 said:


> The most interesting 1000 stone I came across, was from Chroma a few years ago. I don't know who made it as no other manufacturer I tried had something similar. This was a soaking stone, very very hard, very very fast, but also had the feedback of a much finer stone (more like Chosera 3000).
> 
> Sigma 1000 looked to me as being SiC. Searching a bit, looks like it is.


i thought it's just rebranded (New) Cerax 1000?


----------



## kayman67 (Oct 18, 2020)

I don't really know. They sold lots of stones and changed them. My Suehiro 1000 is definitely different, although both soaking stones.


----------



## inferno (Oct 18, 2020)

another good soaker very hard stone(s) - juuma 800 and 1200.


----------



## kayman67 (Oct 18, 2020)

I want one. Never got to it yet.


----------



## zizirex (Oct 18, 2020)

kayman67 said:


> Shapton Pro 12 was 15 in the past, as said above. 2:1 stone
> There are some 15-16k stones out there. Not a very usual grit, though.
> 
> Anyway, higher grits are about skill before the grits themselves. Some stones might make it easier, some not so much. This doesn't make them better as in best possible results, but some results are better than no results or worse. And at some point you choose even without knowing. I do like some stones better than others, but that might be just me.
> One of the most unusual combos is the Sigma 1200 + 13000. Seems so unreasonable to make such a huge jump and for some purposes it is, but for some reason, the 13k really improves edge retention even with more demanding alloys (like ZDP-189 or HAP40). I was quite amazed especially with ZDP-189. I always wondered how such a combo came into existence (since Sigma has 6000 and 10000 that would have been a more convenient choice maybe).


Have you tried the Sigma 13K? any comparison with other ultra-fine grit stone?


----------



## kayman67 (Oct 18, 2020)

Any particular stone in mind?


----------



## zizirex (Oct 18, 2020)

Shapton Pro 12k or Shapton Glass 16k, maybe naniwa Ss 12k?
Im choosing between shapton and sigma


----------



## kayman67 (Oct 18, 2020)

These types of comparisons might be a bit tricky, but I will consider the same knives. 

To start with, Sigma needs some water. Way less than Sigma 10k, but the others don't really need any. 

Sigma offers pretty much the same level of performance and couldn't care less about surface maintenance, while the others are a lot more problematic (Naniwa Super Stone 12k and Shapton Glass 16k in particular). 

Sigma has the brighter finish (with some shirogami as common reference), while Shapton Pro 12k might be the opposite. 
Sigma has the best scratch management I've seen. Takes care of most scratches and always delivers a bright polish. Very consistent behaviour. With some more contrast available, this would have been a crazy finisher.


----------



## zizirex (Oct 18, 2020)

I see, so contrast is much better on Sigma? And brighter mirror polish? How thirsty is the Sigma? Do I need to soak it or just a little bit of running water is fine? Edge quality and speed is very similar I’m guessing?


----------



## kayman67 (Oct 18, 2020)

There is a decent amount of contrast. More like very bright (mirror) and less bright (haze) combo. But it's not the contrast I get from Jnats. 
Under running water is just fine, for about a minute. No soaking. Requires little after. With Sigma 10k I would have to soak it for some time and also use more water. 
Delivers very sharp edges, but might need some care with burr development, I guess. It will develop a micro burr rather fast.


----------



## Kawa (Oct 18, 2020)

kayman67 said:


> I don't really know. They sold lots of stones and changed them. My Suehiro 1000 is definitely different, although both soaking stones.



Did you, or anyone else reading this, ever tried a superstone 1000?

It's the only 1000 I have (Have a chosera 600 as previous step and a shapton pro2000 and superstone 2000 as next step. Not saying I'm using all 3 as progression per knife).
People say 'master the 1000', but I think my ss1000 is my stone I ruin most edges on. Lately I skip it and go chosera 600 -> pro2000.
I find the 1000 very soft, I like the feeling during sharpening, but most of my edges are better if I skip this stone...
it gives a very hazy/matte finish. I can imagine its a nice stone for contrast making. But how is if for sharpening? I want to hear from other users, I dont want to give up on getting better with this stone, if it's a regulair usable stone for edge improving.


----------



## kayman67 (Oct 18, 2020)

All Super Stones are rather soft. With proper consistency/pressure, they work for you. Otherwise, no.


----------

