# Noob question about relative sharpness of different knives



## idemhj (Oct 14, 2014)

Hi. Im relatively new to freehand sharpening which I really enjoy and at which I am  in my own perhaps not sufficiently humble  opinion not all that bad 

Obviously I have practiced quite a lot (I have a Victorinox Chef which is going to end up as a slicer pretty soon  but thats fine)

My stones at the moment are 800 and 3000 Choseras. I also strop on leather with a SiC compound (of unknown grit).

All my knives are sharp  perhaps not by your standards, but certainly by mine. However, the relative sharpness I can get some of them to has surprised me a little bit.

- The absolute sharpest is  fortunately  my newly bought Itinomonn semi-stainless 240 gyuto (and I am talking _my_ edge, not OOTB  I figured that since it was now my knife, it had to live with my edge  or lack thereof :O).

- Number two is an old Mac Pro petty.

- Number three and four (I really cantt separate them) is my old Tojiro DP gyuto and my carbon K Sab slicer.

That surprises me somewhat. Shouldnt I be able to get the K Sab sharper than that? Or is this to be expected from that rather soft carbon steel? Do I perhaps need a finer stone to bring out its potential? I know that the K Sab will not hold an edge very well, but Im talking right off the stones.

BTW, this is not based on a single sharpening, both the Tojiro and the K Sab have been sharpened several times.

Thanks in advance for any input  great forum, Ive learned a lot!


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## Benuser (Oct 14, 2014)

Not going to be exhaustive, just a few remarks. Sharpness is perceived very differently. A gross edge on a poor soft stainless with large carbides will be called sharp by some. A very refined, polished edge on a razor that allows a smooth shaving is another category. 
Speaking of steel types, will it take an acute edge? Does the fine grain allow a refined polished edge?
A soft French carbon won't hold an edge with an inclusive angle under some 40 degree, Aogami Super will easily hold a 25 degree inclusive angle. With its fine grain the French will be very sharp, with its acute angle the AS will be very sharp as well, but differently.
My soft carbons benefit a lot by sharpening on a Naniwa Snow-White 8k.


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## Benuser (Oct 14, 2014)

Just wondering about SiC as a compound. Are you sure it isn't Cr2O3?


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## idemhj (Oct 14, 2014)

Benuser said:


> Just wondering about SiC as a compound. Are you sure it isn't Cr2O3?


I am actually pretty sure about that - a grey paste. Anyway, thanks for the repley, it may well be that the question is only partially meaningfull.


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## Zwiefel (Oct 14, 2014)

This thread might be helpful.

http://www.kitchenknifeforums.com/showthread.php/7689-sharpness-vs-keenness


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## idemhj (Oct 14, 2014)

Benuser said:


> My soft carbons benefit a lot by sharpening on a Naniwa Snow-White 8k.


Ben, I have been thinking of getting a new finer stone. Do you think that the Snow-White would be better than the Naniwa Pro 5000? (At some point i will also need somthing coarser.)


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## JDA_NC (Oct 14, 2014)

Relative sharpness is an interesting thing.

I wish I could have more hands on experience with some of the edges that the professional sharpeners here can produce. I'm happy with what I'm getting but I know there is a next level that I haven't reached yet.

I've gotten a few knives from Jon at JKI and the edges have varied (which is in no way a critique of his skills - please don't misunderstand) but one in particular really blew me away. It didn't feel all that sharp to the touch/3 finger test, but when I cut paper it fell right through and gave that nice audible feedback where you know it's sharp. I used that edge for about two weeks in a professional kitchen on poly boards and only stropped it on a stone twice. I usually sharpen my knives every (other) day and even on the same knife, I can only go 3 to 4 days without having real edge failure. At least by my standards.

Like Benuser said, what sharp is depends a lot on the person. If you're a home cook and you like to sharpen your knives and don't mind taking them to super high polishes/grits - then using 8k+ edges could be fun to play with. If your edge fails when you're making dinner for the family, it's not that big of a deal. If my edge fails within an hour of a 12 hour shift... it's going to be a long night. Even with back up knives. So I personally prefer coarser, toothier, and in my experience, more durable edges that will take a beating instead of a smoother razor sharp one.

And one of the biggest factors I've found is knife geometry/thinness. It sounds like your sharpest knives go from thinnest to thickest. Thinner edges & knives tend to be easier to sharpen, can take more acute angles, and perform better even as the edge dulls.


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## Benuser (Oct 14, 2014)

idemhj said:


> Ben, I have been thinking of getting a new finer stone. Do you think that the Snow-White would be better than the Naniwa Pro 5000? (At some point i will also need somthing coarser.)


I use the 8k a lot directly after my Chosera 2k, skipping the Chosera 5k I don't like that much. So, the jump from your 3k to this 8k should be rather easy.


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## Benuser (Oct 14, 2014)

JDA_NC said:


> Relative sharpness is an interesting thing.
> 
> I wish I could have more hands on experience with some of the edges that the professional sharpeners here can produce. I'm happy with what I'm getting but I know there is a next level that I haven't reached yet.
> 
> ...



I prefer a thin blade with a relatively obtuse polished edge. It will hold and can easily be repaired. That's why I love relatively soft carbons I can restore with a few strokes on Cr2O3 or a very fine stone.
The best critic I got from an absolute ignorant about sharpening that a blade I had sharpened didn't feel sharp but cut like crazy -- I had put a huge microbevel on a Global after a bit of thinning.


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## psfred (Oct 14, 2014)

You may need to thin the knifes that don't seem "sharp" -- the keenest narrow angle edge in the world will feel dull if the knife is so thick just behind the edge that even paper tears rather than being cut by the edge itself. Doesn't take to many sharpenings to get a fairly thick blade behind the edge, especially on something like a Victorinox which isn't all that thin to start with.

Quick test is to cut something thick and brittle, like a firm apple or a large carrot. Thin slices will show the actual edge sharpness as the slice will flex easily out of the way. Thick slices or splitting a halved apple into quarters will result is the flesh breaking if you need to thin the knife, and will show up as a rough surface at the bottom of the cut.

You will also hear a crunch rather that a slicing sound. 

You can also measure the thickness with a dial caliper.

You can put an amazing edge on the Sab, but it won't last very long at all. 

It is also possible you are not removing the burr on the Tojiro, VG-10 can have a very tenacious but very small burr that "hides" the edge and feels dull. Deburr carefully but completely before deciding it's not sharp. It will also take more grinding that a softer knife to get really sharp, make sure you are fully apexing the edge. 

Peter


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## zitangy (Oct 14, 2014)

psfred said:


> You may need to thin the knifes that don't seem "sharp" -- the keenest narrow angle edge in the world will feel dull if the knife is so thick just behind the edge that even paper tears rather than being cut by the edge itself.
> 
> 
> Peter



I am of the opposite view... My thick cleaver and axe still feels sharp. Thickness behind the edge wld most prob cause wedging and a different feel adn sound when slicing paper.

When 2 angles meet and they are pointy.. it will still feel sharp and the feel on the finger tips wld be bitey.. the keener / sharper it is, you wld feel it "granularly" across the finger print lines....

I believe that kitchen knives a re sharpened ard 15 to 20 degrees and an axe ard 35 degrees.

.. just my take.
rgds
d


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## idemhj (Oct 15, 2014)

JDA_NC said:


> And one of the biggest factors I've found is knife geometry/thinness. It sounds like your sharpest knives go from thinnest to thickest. Thinner edges & knives tend to be easier to sharpen, can take more acute angles, and perform better even as the edge dulls.


Yahh, I think you're spot on. Stupid of me not to notice that myself. Well then, got to enter the scary world of thinning... I always knew the day would come.


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## Pensacola Tiger (Oct 15, 2014)

idemhj said:


> Yahh, I think you're spot on. Stupid of me not to notice that myself. Well then, got to enter the scary world of thinning... I always knew the day would come.



Thinning isn't scary, just tedious.


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## Benuser (Oct 15, 2014)

Don't wait too long. Let it be a part of your regular sharpening.


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## idemhj (Oct 24, 2014)

Thanks for the advice. I thinned my Tojiro and K Sab, and both cut a lot better now. It wasn't really that scary, and I didn't scratch the blade too badly - nothing that can't be fixed with a little sandpaper. I am definetly going to let thinning be a part of my regular sharpening


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