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Toothy polish question.

glassjaw

glassjaw

Joined
Jul 28, 2014
Messages
283
I work at a restaurant in which we do a fair amount of beef cutting. I happened across one of jdavis's videos about putting an edge on the blade with a coarse stone and finishing with a polishing compound, leaving a polished toothy edge. I was wondering how effective that would make a kitchen knife? It would bite well for sure.
Any ideas or comments would be great. I may steal one of the knives from work and work on it just for grins.

Gabe
 
Depends on the kitchen knife, would work for some but you need to first define coarse. Most food cutting tasks should be performed with a finer edge anyways, you want to cut the food not rip it to shreds.
 
Even toothy it should be ground fairly thin at and behind the edge.

Personally I do not like to strop my coarse edges on anything more than plain paper or newsprint. If the steel is a lower RC Western cutlery, sometimes a coarse edge steeled on a microbevel against a smooth meatpackers steel or the rim of a glazed bowl or Pyrex dish works real well too. That way the edge is worked thin across by plastic deformation/burnishing but still has a lot of catch. This is how I do my wife's dedicated kitchen knife.

This type of edge (depending) can hold up really well. I run my utility slicers to around 600-800 grit (1k-1200 JWS) and get good performance. For chopping and dicing I go with a finer finish.
 
I say you have to experiment with the particular blade to find out what works best. Jason and HH are both REALLY experienced, so definitely pay attention to what they have to say. For kitchen work on typical kitchen cutlery (like HH said, lower hardness steels) his recommendation of around 600 grit is often repeated. There's a good reason that the Spyderco SharpMaker's gray rods are right at 600 grit. :)

I've had pretty good luck using the 22 micron belt on the WSKO. That's right at 450 grit or so. Edges seem to hold up pretty well. In fact they hold up much longer than if I finish them with the X4 belt instead (that's about 1500 grit). With the X4 they will pop hairs off of your arm and scare you if you catch your fingernail with them. But the edge doesn't last nearly as long as with the X22 belt.

But like they said above, it's all about what you'll be cutting and how. For utility tasks like cutting open cardboard boxes, I've found that a VERY coarse edge, that's then stropped or touched up on a fine belt works very well. I settled on doing the edge with a 100 micron belt and then lightly hitting it on the X4 belt for burr removal and a little polish. That edge is really toothy and lasts pretty well for box cutting.

Brian.
 
The most common stone used in professional settings would be the 1k red brick stone. This grit level allows removal of minor damage and a refined but still quite toothy edge that tends to last the longest in a hard days use. German knives and Japanese knives will both work well when finished on this grit level of stone.

One of my favorite stones for creating a toothy polished edge is the Naniwa 2k green brick, combined with a good 1k stone these are the two stone relied upon by numerous professionals for sharpening all types of kitchen cutlery. I have also used the Chosera 400 in conjunction with the Naniwa 2k green brick, killer combo that has given me more positive feedback than any other sharpening method.
 
Thank you for all the help gentlemen. What I was thinking was finish on a 1000 grit and then hone. I think I may look at the 2k naniwa though. I have a few kitchen knives at home the could be experimented upon. . If jumped from a 1k grit stone to a 4k stone, do you think it would still leave some tooth?

Gabe
 
If you held off and only did a bit of backhoning on the 4k it would work but might also be tricky to consistently replicate the effect. It will also depend on what type of waterstone you're using and the specific steel the knife is made from. Experiment away!
 
The bottom line is a toothy edge has less contact cross section doing the cutting so no matter how it is stropped it cannot be maintained as long as an edge with a finer finish. Its a trade
off.
 
That depends on the properties of whatever one is cutting. On materials with some give, the toothier edge will have more contact area.

Another consideration is that pressure into the edge seems to be one of the prime determinants of how rapidly an edge will wear. If a given material cuts more efficiently (less applied force) with some drawing separation, the toothier edge will last longer than a finer edge that requires more initial force to create a pressure cut. If a material parts more readily with a fine edge pressed into it and requires more force for the toothy edge to cut it, that fine edge will last longer.
 
HeavyHanded said:
That depends on the properties of whatever one is cutting. On materials with some give, the toothier edge will have more contact area.

Another consideration is that pressure into the edge seems to be one of the prime determinants of how rapidly an edge will wear. If a given material cuts more efficiently (less applied force) with some drawing separation, the toothier edge will last longer than a finer edge that requires more initial force to create a pressure cut. If a material parts more readily with a fine edge pressed into it and requires more force for the toothy edge to cut it, that fine edge will last longer.
Click to expand...

I don't know if it could be studied objectively, there are to many variables. When I discuss this with someone at my shop I use a section of old cotton tee-shirt, clamped in a vise, to demonstrate how a toothy edge cuts, compared to a refined edge. When cutting the tee-shirt material with a toothy edge the jagged "teeth" along the edge do the cutting; I'm assuming there are minute gaps between the teeth with the rough edges doing the cutting. With the refined edge there are no "teeth" to cut with so the cutting is being accomplished using an uninterrupted apex. It would follow that the toothy edge would break down before the refined edge doing the same cuts with the same materials, because there is less contact area doing the cutting. Now if cutting soft cheese :)
It would be interesting to see this action under high magnification.

Fred
 
Given that there is a lot of wiggle room for what defines "toothy", most variation is a lot less than one might think in terms of how proud those teeth are. That said, what I tend to find is that if the edge is primarliy for draw cutting - synthetics, fibrous materials - the teeth will last a long time because they employ a sawing action as well as some penetration. The wear on the teeth is no more than the fine edge might see when pressed into a more dense material. Its when one drives the toothy edge into hard materials, or attempts to saw with the fine edge, that they will dull rapidly. The finer edge has less variation, so as it dulls it cannot fall back on having that variation to draw with, and the rougher edge carries too much resistance with it into the cut.


I had to learn this a couple of times before I embraced the use of different edge finishes for different tasks when practical. All else being equal it can make a big difference in longevity. Even for general use I tend toward a toothier edge, reserving the bright polish for dedicated chopping/carving tools, and to the OP, I carry this right through into the kitchen. Not that I'm much of a foodie, but I do have different edge finishes for different tasks.


And then some steels simply tend to take a given finish better than another to a degree it overshadows any dedicated edge prep - in that case I don't fight it and just sharpen it up as it likes.

I actually did a bit of a test relating to this topic that had micrographs associated with it. Was a difference between 800 grit and approx 1500 carving endgrain red oak with a bit of a draw and hard pressure, trying to generate both wear mechanisms. The rougher edge actually held up a lot better than I expected, though the finer edge did hold up longer in this application. It took a lot of work to tear off those teeth and the edge was still pretty darn sharp.


http://www.bladeforums.com/forums/s...r-micrographs?highlight=edge+wear+micrographs
 
HeavyHanded said:
Given that there is a lot of wiggle room for what defines "toothy", most variation is a lot less than one might think in terms of how proud those teeth are. That said, what I tend to find is that if the edge is primarliy for draw cutting - synthetics, fibrous materials - the teeth will last a long time because they employ a sawing action as well as some penetration. The wear on the teeth is no more than the fine edge might see when pressed into a more dense material. Its when one drives the toothy edge into hard materials, or attempts to saw with the fine edge, that they will dull rapidly. The finer edge has less variation, so as it dulls it cannot fall back on having that variation to draw with, and the rougher edge carries too much resistance with it into the cut.


I had to learn this a couple of times before I embraced the use of different edge finishes for different tasks when practical. All else being equal it can make a big difference in longevity. Even for general use I tend toward a toothier edge, reserving the bright polish for dedicated chopping/carving tools, and to the OP, I carry this right through into the kitchen. Not that I'm much of a foodie, but I do have different edge finishes for different tasks.


And then some steels simply tend to take a given finish better than another to a degree it overshadows any dedicated edge prep - in that case I don't fight it and just sharpen it up as it likes.

I actually did a bit of a test relating to this topic that had micrographs associated with it. Was a difference between 800 grit and approx 1500 carving endgrain red oak with a bit of a draw and hard pressure, trying to generate both wear mechanisms. The rougher edge actually held up a lot better than I expected, though the finer edge did hold up longer in this application. It took a lot of work to tear off those teeth and the edge was still pretty darn sharp.


http://www.bladeforums.com/forums/s...r-micrographs?highlight=edge+wear+micrographs
Click to expand...

I'm of the very same mind, well said. It all goes back to assessing an edge, ascertaining its possibilities, choosing the right edge for the task at hand and maintaining that edge in a proper manner, giving it longevity.

Fred
 
So much info it's almost overwhelming. Thank you gentlemen! I am going to have to read it all again to have it sink in. The primary purpose of the knife would be cutting beef. It's basically just processing down a top roast, so taking off fat and silver skin to strip and dice. Basically stew meet. And the knife I use no one else really uses on anything other then beef. So I'm not to concerned about the edge dulling to much. But other hands will be on it and proper knife use is not always on their minds. But my boss lets me do anything with the knives, so I'm going to take it this weekend and see what tooth I can put on it and see what happens. I'm definitely going to have to read everything again and I may be back with some questions. Thanks again guys!

Gabe
 
Meat cutting should always be done wth a very sharp knife so you don't destroy the cell structure of the meat. The Naniwa green brick would provide just the right level of refinement and cutting ability for such tasks. Though it's rated at 2k it yields a much higher level of polish, if you work the stone long enough it's easy to create a 4k or better edge on most hard steels. It will remain toothy on softer steels, harder steels bring out more of the polishing effects.

It's also an ideal stone for German cutlery, handles the soft stainless very well and makes it easy to deburr.
 
This sounds like a very backwards approach to sharpening. If you stop with a coarse stone, the use compound, all the compound will do is wear at the edges of the "scratches" created by the coarse stone. The compound won't take off enough metal to refine the edge further. My suggestion, if you want something in between polished and non, is to stop somewhere in the middle. For me, that is about 1000 grit (edge pro stones). For my kitchen knives (except fillet knives) I sharpen to 1000 grit, to keep some tooth for things like skin and tomatoes. For my pocket knives I sharpen to 8000 then use a 1/2 micron diamond compound followed by 1/4 micron. For honing my kitchen knives I use a 1200 grit ceramic rod (another reason I sharpen my kitchen knives at 1000), and I use 5 micron for touching up my pocket knife if I get an edge fold.
 
Livin' On The Edge said:
This sounds like a very backwards approach to sharpening. If you stop with a coarse stone, the use compound, all the compound will do is wear at the edges of the "scratches" created by the coarse stone. The compound won't take off enough metal to refine the edge further.
Click to expand...

Not true, the edge will refine and become sharper. This is a very proven fact.
 
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