Do I need a polishing stone?

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agp

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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?
 
Depends on the kind of steel your knives are made of, and whether you can achieve a complete deburring with the 3k.
 
No single bevel. I have some blue and some stainless. I don't use the stainless much though.
 
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.
 
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.
 
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.....
 
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.
 
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.
What do you the finer stones for?
 
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.
 
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.
 
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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....
 
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.
 
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.
 
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.
 
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.
 
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You do. Finer edge stays sharper longer.
 
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.
 
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.
 
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.
 
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.)
 
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.
 
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



 
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