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View Full Version : How do you a define a screaming-sharp edge?



Marko Tsourkan
10-27-2011, 05:06 PM
There are probably as many definitions as there are people sharpening, but what would be a good basic definition that could be used as a reference for sharpness?

I was thinking an edge that can pierce skin of a ripe tomato on contact is a screaming-sharp.

M

Eamon Burke
10-27-2011, 05:09 PM
As far as buffed edges go, the hanging hair test is my go-to. Mostly because I only put edges like that on straights, and those are supposed to breeze through hair. Push cutting tissue is a good one too.

tk59
10-27-2011, 05:20 PM
If you're asking what kind of edge you should be putting on your knives out the door, I probably wouldn't go past 5k and then whatever it takes to deburr. I think most users are going to benefit most from that edge. Piercing the tomato on contact is a nice trick and I like to get my edges there but it's really not any more useful than a nice 5k edge with maybe a little extra refinement on a strop.

welshstar
10-27-2011, 07:44 PM
Think there are two answers.

What edge is good for a high use chef and what edge is good for a low use home cook, I think tk59 has far more knowledge than a newbie like me and I would absolutely defer to him technically on what might be the best compromise but if im buying a knife I want it screaming sharp OOB

obtuse
10-27-2011, 07:47 PM
Someone should post a link to the video salty just did on Mario's 250mm gyuto. That's screaming sharp to me...

Vertigo
10-27-2011, 08:09 PM
... but if im buying a knife I want it screaming sharp OOB
Get used to disappointment. ;)

tk59
10-27-2011, 08:28 PM
I think Murray has the right idea. He puts a nice, toothy 6k edge on it that will push cut a tomato with a few strokes on a loaded strop. It cuts effortlessly with just a little foward or backward motion.

Pensacola Tiger
10-27-2011, 08:54 PM
The same edge should serve both a pro and a home cook. Edges that cut tomatoes with the weight of the blade and hair-whittling razor edges are tributes to the skill of the sharpener, but neither will survive contact with a board in real world use.

just my 2 cents.


Think there are two answers.

What edge is good for a high use chef and what edge is good for a low use home cook, I think tk59 has far more knowledge than a newbie like me and I would absolutely defer to him technically on what might be the best compromise but if im buying a knife I want it screaming sharp OOB

Sarge
10-27-2011, 10:06 PM
The same edge should serve both a pro and a home cook. Edges that cut tomatoes with the weight of the blade and hair-whittling razor edges are tributes to the skill of the sharpener, but neither will survive contact with a board in real world use.

just my 2 cents.

I agree

Marko Tsourkan
10-27-2011, 10:09 PM
Thanks fellas.

So the screaming edge in practical terms would be 5-6K edge stropped. What do you load your strop with?

M

Pensacola Tiger
10-27-2011, 10:30 PM
I like Dave's .25 micron diamond on leather.


Thanks fellas.

So the screaming edge in practical terms would be 5-6K edge stropped. What do you load your strop with?

M

Cadillac J
10-27-2011, 10:40 PM
I always stop at 5K SS then strop with 1 micron diamond, and its the perfect finishing point for me. Those edge will past all the tests we see here, and have nice retention.

Juts for dinner with my Takeda kiritsuke I was chopping up mushrooms, onions, green pepper, garlic and a carrots for a chili I was making...then was still able to push cut a super ripe tomato straight down with almost no pressure multiple times, even after all that board contact.

Eamon Burke
10-27-2011, 10:56 PM
Oh, see I thought you meant what is the best example of an absurdly sharp edge, not what I use/put on kitchen knives.

My favorite edge is off a rika 5k, depending on the steel and application, I either strop on .5 CrO for polishy edges for very good steel, or I take an idahone rod to it, get some teeth on it. Push cutting is fairly rare in a real kitchen. While all cutting tests are fun, push cutting tomatoes is a bad idea.

Marko Tsourkan
10-27-2011, 11:09 PM
The reason I asked is that I also stop at 5K Rika, unless I continue on one or two nat stones. The edge is sharp, but not screaming-sharp, so I was wondering what you guys do to put it just a little bit higher, so it looks good on camera. Not that I am about to start filming things, just curious.

M

Sarge
10-27-2011, 11:56 PM
Oh, see I thought you meant what is the best example of an absurdly sharp edge, not what I use/put on kitchen knives.

My favorite edge is off a rika 5k, depending on the steel and application, I either strop on .5 CrO for polishy edges for very good steel, or I take an idahone rod to it, get some teeth on it. Push cutting is fairly rare in a real kitchen. While all cutting tests are fun, push cutting tomatoes is a bad idea.

Hear ya on the tomatoes, although almost all my other cuts are push cuts, mostly because I use my Kiritsuke nearly exclusively for my veg and then my Kiri-gyuto I push cut with out of habit.

For me working the mud on the Kitayama produces the best edge for food. I don't strop btw

Eamon Burke
10-28-2011, 12:38 AM
I should probably specify that I mean drop-down hammer style push cutting. Not pash cuttong like in japanese knife society's negi cutting vid. I do that myself all day. But I dont hammer tomatoes into paper. Sometimes I cut stuff in mid-air, but t hats for fun.

tk59
10-28-2011, 01:17 AM
I like Dave's .25 micron diamond on leather.Yeah. I like Dave's old leather. This new stuff is totally different, imo. I'm also testing 1 micron diamond and boron carbide. I think I might be switching to one of those over the 0.25 micron stuff.

NO ChoP!
10-28-2011, 01:30 AM
I've found I like the 1 micron over the .25 I had... wasn't even sure the .25 was doing anything more than bare leather.

tk59
10-28-2011, 01:54 AM
...wasn't even sure the .25 was doing anything more than bare leather.It definitely does something. The question is two-fold: Is the edge you're putting to the strop too damaged for the 0.25 micron stuff to make a difference? and is the 0.25 micron effect going to last long enough. I think it's fine for a home kitchen where you can strop everytime you cut something but for a pro kitchen or just someone who doesn't want to do maintenance too often, it's not ideal.

JohnnyChance
10-28-2011, 02:12 AM
Thanks fellas.

So the screaming edge in practical terms would be 5-6K edge stropped. What do you load your strop with?

M

2 micron Silicon Carbide on Balsa...but you knew that already.:thumbsup:

Also just started using 1 micron poly diamond which has been getting me pretty good results so far.

Cadillac J
10-28-2011, 10:06 AM
I should probably specify that I mean drop-down hammer style push cutting. Not pash cuttong like in japanese knife society's negi cutting vid. I do that myself all day. But I dont hammer tomatoes into paper.

+1 million!

Cadillac J
10-28-2011, 10:09 AM
I'm also testing 1 micron diamond ...I think I might be switching to one of those over the 0.25 micron stuff.

Oh, I'm sure you will switch. I've never seen a reason to go below that.

Marko Tsourkan
10-28-2011, 10:19 AM
2 micron Silicon Carbide on Balsa...but you knew that already.:thumbsup:

Also just started using 1 micron poly diamond which has been getting me pretty good results so far.

Right, but knowing something should not prevent one from learning more. :)

Schtoo
10-28-2011, 12:05 PM
Depends on what the blade is, and what it's going to cut...

A knife, if it'll cut chicken cleanly with minimal effort and no stringy bits that annoy me, then that's all I want. If the knife will do that, then it'll do anything I reckon.

A chisel, if it'll pop arm hair (not shave, the hairs need to mimic a missile) at 30 degrees, it's good.

A plane blade, needs to pop arm hair while held off the skin. Or shave my beard. Or split free hanging hairs.

A razor, needs to shave a dry beard cleanly, no irritation. I know this isn't proper, but I'm very gun shy of my straight at the moment...


Oh, that all needs to be off the stone, but the razor may be rubbed over untreated leather to sort it out properly.

I like my stuff sharp, and it's not like I'm lacking for materials to get that. It's more a case of "what's going to get me my 'sharp' without annoying me too much?" is the trick.

If the blade is sharp enough to cut what needs cutting and do it as cleanly as it needs to be done, that's enough thank you very much. :)


But you shouldn't listen to me. My main cooking knife looks like recycled garbage.

(I just need to remind myself to use a light touch, otherwise it sticks into the chopping board. Looks terrible, but it is sharp... )

Stu.

chazmtb
10-28-2011, 12:17 PM
For me, a good edge on a gyuto is cutting a carrot without any effort or cracking sound, similar to the sound you make when you cut a white sheet of copy paper. That's a good edge.

tk59
10-28-2011, 12:58 PM
...cutting a carrot without any effort or cracking sound...That's important but, if I'm understanding you correctly, it varies wildly depending on blade geometry. Maybe if you're making thin slices, it would be more consistent but then again, I never hear cracking while making thin slices...

JohnnyChance
10-28-2011, 02:40 PM
That's important but, if I'm understanding you correctly, it varies wildly depending on blade geometry. Maybe if you're making thin slices, it would be more consistent but then again, I never hear cracking while making thin slices...

+1. Geometry and technique seem to matter more in the carrot cracking department that actual sharpness.

NO ChoP!
11-01-2011, 02:02 AM
It definitely does something. The question is two-fold: Is the edge you're putting to the strop too damaged for the 0.25 micron stuff to make a difference? and is the 0.25 micron effect going to last long enough. I think it's fine for a home kitchen where you can strop everytime you cut something but for a pro kitchen or just someone who doesn't want to do maintenance too often, it's not ideal.

To answer part 2 first, no, a stropped edge in general will not hold up to a days work of prep. To answer part 1, I usually only strop a fresh edge, I am pretty immaculate with maintenance; it's almost a ritual. I have learned to be very gentle on my edges through the years. If I'm going to be rough, I have a knife for that, and it would never touch a strop...

David Metzger
11-06-2011, 02:11 AM
10 degrees per side, screaming sharp, 15 degrees per side - sharp, 20 degrees per side - still cuts ok. Tomatoes, hair and paper are all fun.