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edge retention after sharpening

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Goorackerelite

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So I've sharpened all my knives and have developed good apexes and good burr removal. It's razor sharp, but how do I get that mythical edge retention that people are talking about? I can barely get through a few min of prep while keeping that scary sharp edge. Is a cutting board that I need or cutting technique? This is driving me mad. I have white steel, blue steel, super blue... all hair popping sharp but they all lose that scary sharp edge with in a few min. are my expectations too high? should I just accept the fate that I will have to hone them after a few min of use to restore the scary edge ?
 

Dhoff

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I'm likely underqualified to answer this.

Some things can help identify whether an issue is present.

A short video of you sharpening.
Knowledge of what stones you use.
An example or two of the knives you use.
If possible use a microscope and a camera/phone to take pictures of the edge. Otherwise a magnifying glass and inspect it yourself.
Also what cutting board. If you e.g. use glass or granite (shudder) it makes perfect sense.

Knee jerk reaction: sounds to me like a wire edge.
 

Rangen

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The two conventional answers I've heard are:

1) Try making a microbevel

2) Don't polish the edge too finely. For kitchen knives, a lot of people stop at 1000 grit, or maybe 2000 for the kinds of nice knives you're talking about, then strop. That produces a less hair-popping edge that is more durable for kitchen use.
 

M1k3

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In no particular order without more information, I'd guess burr/wire edge, cutting board (glass, granite, metal, bamboo or hard poly boards) and/or high expectations.




:cool: @TSF415
 
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Hz_zzzzzz

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It bothers me too that some of my knives couldn't cut paper towel after 2-3 meals unless I strop them. There are many factors I can think of. Cutting board. Potential wire edge or foil edge. Stone grit too high. Or maybe expectation too high.

I wonder what a denka would do with paper towel. Without stropping, after how many meals they can no longer cut paper towels? I ordered my denka but it hasn't arrived so really curious.
 

PappaG

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It bothers you, why? Because you cannot make a tasty paper towel sandwich after using your knife for a bit? J/K.... I love to watch professional sharpeners sharpen and cut paper towel with ease. I often strive for that level of sharpness, but I'm not sure its a realistic expectation after using the knife...for whatever number of meals... I don't know what is reasonable... so long as your knife continues to meet your expectations cutting food....
Ok. I'll bow out of this discussion because I'm clearly cranky today...
 

kayman67

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Well, you might be able to do it, it is doable, but that's not the real goal. I would be really worried about not being able to cut a tomato properly. That would be a problem if within minutes there would be no edge.

Reasons could be many, very hard to say what's what in front of a screen. Different things happened. You might not remove enough fatigued alloy. And sometimes it's not even about quantity. You just need to start a bit lower grit. You might induce fatigue yourself while sharpening. You might have a too thin edge for your needs (even though seems like it would cut great right after sharpening). You might have a false edge (that also cuts great for a few moments). You might twist the knife into the cutting board and you either practice clean cuts or change the edge to suit this. You need to try different things and see what happens. Yeah, maybe starting with some good edge leading passes to finish, even high passes, no strop and see where that takes you. Adjust from there. You could also put that edge against a hard fine stone, think in terms of surgical black, dalmore blue. Apply a bit of pressure and see just how stable it is. Either way, it should improve and remove some of the weaknesses. This helped a lot of people.

Full disclosure, none of those alloys are great with edge retention, but here seems a bit too soon.
 

Hz_zzzzzz

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It bothers you, why? Because you cannot make a tasty paper towel sandwich after using your knife for a bit? J/K.... I love to watch professional sharpeners sharpen and cut paper towel with ease. I often strive for that level of sharpness, but I'm not sure its a realistic expectation after using the knife...for whatever number of meals... I don't know what is reasonable... so long as your knife continues to meet your expectations cutting food....
Ok. I'll bow out of this discussion because I'm clearly cranky today...
When I started to learn sharpening, my goal was to push cut printing papers. After that, the goal became paper towel. Then it became hanging hair. Then it became a single layer of toilet paper (still at this phase now; my knives cut toilet paper, but not as cleanly as with paper towel). I once saw a video where a guy can cut hanging hair after slicing into a piece of wood several times ( ). So I know the life of initial sharpness is where I can always improve myself. It's just part of the journey. The more it bothers me, the happier I would be "if" I finally overcome it.
 
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Dave Martell

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So I've sharpened all my knives and have developed good apexes and good burr removal. It's razor sharp, but how do I get that mythical edge retention that people are talking about? I can barely get through a few min of prep while keeping that scary sharp edge. Is a cutting board that I need or cutting technique? This is driving me mad. I have white steel, blue steel, super blue... all hair popping sharp but they all lose that scary sharp edge with in a few min. are my expectations too high? should I just accept the fate that I will have to hone them after a few min of use to restore the scary edge ?

There's many factors at play regarding edge retention yet in my experience with Japanese knives there are two things that most people do incorrectly to prevent themselves from achieving decent edge retention. (Assuming that all variables like using a good cutting board, good cutting technique, etc are good to go.)


1. Improper Burr/Wire Edge Removal
Most sharpeners just lightly stroke the edge on a fine stone/strop and call it done. I feel that if your edge is weak enough to flex like this using such light pressure then it's absolutely weak enough to flex under cutting pressure.

It's one thing to get a knife scary sharp, or make an edge pretty looking, but altogether another thing to make an edge that will last a couple of weeks of pro use.

When learning to sharpen I strongly suggest deburring after each and every stone in your progression. Pull the loose burrs off and get them out of the way so that the next stone can abrade/refine the edge. This means to pull/cut into a substrate that will grab the burrs and pull them away and off of the cutting edge without dulling the knife. Some use cork, wood, or thick felt for this.


2. Finishing With The Wrong Grit
For general purpose kitchen use I feel that going beyond a 5k stone to be problematic. Actually most 5k stones are too fine really but I have to pick a number to speak to, don't I? If too fine of a stone is used to finish on you'll have too fine of an edge, an edge with no "teeth" to bite into your product. Also worth noting is that it's VERY easy for the inexperience sharpener to wobble a bit and cut multi-faceted bevels and when this is combined with the use of polishing stones what you get as a result is a nicely rounded over edge with no bite and very slick. If the wobbler sharpener stops at a coarser grit he'll still have a multi-faceted edge yet his edge will have some bite still.

Use of a leather strop can lead to poor edge retention - if used incorrectly - that is with poor technique. Similar to the above mentioned wobble problem the incorrect stropping on leather will provide a rounded over edge.

Using chromium oxide on a strop will make for a frightening scary edge for sure, an edge that will slay paper towel yet fail on a tomato once the cutting board is touched. I believe this is because chromium oxide has rounded particles that polish the edge too much. *Note - chromium oxide can be wonderful for use on a yanagiba though, the level of sharpness and cut provided from this stuff, for this particular knife/task is crazy! A much better choice for the general use stropping compound is something like diamond spray as this stuff will scratch at the edge and provide a rougher cutting surface, even if more refined than that provided by the last stone used - a best of both worlds solution.



PS - Some level of scary sharpness, even the slightest bit, will be lost upon initial use - this is to be expected. What's not acceptable is a failing edge, an edge that doesn't cut after it's initial use.
 
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Benuser

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With Aogami, I get far better edge stability by starting with a medium-coarse stone. Don't look for extremely low angles. Better have it very thin behind the edge and ending with a conservative primary edge.
As said before, edge retention has often all to do with complete deburring — after every stone.
 

Jason183

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If you do 1000-3000-8000, the knife will be scary sharp but will dull fast, if you do 1000-5000, or just bevel resetting on a 1000 grit stone, It won’t cut as smooth as first method but the edge retentions Last longer. Especially if you working in a busy environment, only need to sharpen your knives on 800 or 1k grit stone only, never past 3k grit.
 

Kawa

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I think ive read muliple times that the really fresh of the stone sharpness can't be maintained for more then a few minutes.
So my guess is the expectation are a bit high. At least, i assume your knives wil still cut very clean, but just that little bit extra it had fresh of the stone is gone?



Also, and this is also for my learning, what is to be expected from carbon steels like white and blue for edge retention in general versus a proper powder steel or SS even?
Mostly i read people comparing blue to white, and blue (mostly as) has better edge retention compared to white (if properly threated etc), but isnt it still all relative?
Isn't carbon steel especially good in 'ease of sharpening' and 'getting the sharpest', but isn't edge retention something that is one of the weaker points of normal carbon steel? I might be wrong, please correct me if so.
If im right, how were your expecation for these steels? Because the stories around blue and white can be kind of mythical and might raise the wrong expectation for edge retention?
 

BillHanna

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If you do 1000-3000-8000, the knife will be scary sharp but will dull fast, if you do 1000-5000, or just bevel resetting on a 1000 grit stone, It won’t cut as smooth as first method but the edge retentions Last longer. Especially if you working in a busy environment, only need to sharpen your knives on 800 or 1k grit stone only, never past 3k grit.
Reading this over and over again has saved my future wallet hundreds of dollars.

God bless us, everyone!


now my only decision is cerax 1k and 3k or gesshin 1k and 4k
 

kayman67

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Well, not entirely true, but Dave Martell covered it above. Gets a lot harder with finer stones.
 

M1k3

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I think ive read muliple times that the really fresh of the stone sharpness can't be maintained for more then a few minutes.
So my guess is the expectation are a bit high. At least, i assume your knives wil still cut very clean, but just that little bit extra it had fresh of the stone is gone?



Also, and this is also for my learning, what is to be expected from carbon steels like white and blue for edge retention in general versus a proper powder steel or SS even?
Mostly i read people comparing blue to white, and blue (mostly as) has better edge retention compared to white (if properly threated etc), but isnt it still all relative?
Isn't carbon steel especially good in 'ease of sharpening' and 'getting the sharpest', but isn't edge retention something that is one of the weaker points of normal carbon steel? I might be wrong, please correct me if so.
If im right, how were your expecation for these steels? Because the stories around blue and white can be kind of mythical and might raise the wrong expectation for edge retention?
Yes and no regarding edge retention. White, blue and other common carbon steels are low alloy, low edge retention. Then there's carbon steels like T15, 10v, zwear, etc. that have higher amounts of tungsten and/or vanadium, high alloy, higher edge retention.
 

Kawa

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Yes and no regarding edge retention. White, blue and other common carbon steels are low alloy, low edge retention. Then there's carbon steels like T15, 10v, zwear, etc. that have higher amounts of tungsten and/or vanadium, high alloy, higher edge retention.
Thx for clearing that up. TS is dealing with simple carbon steels if i read correctly.
I've got myself a blue2 petty a month ago, my first and only simple carbon steel knife. I was a bit dissapointed by the edge retention myself, compared to my aus10 SS gyuto. Ofcourse, the petty is much thinner, but I clearly notice a difference in edge wear, testing the same amount of veggies during the same diner preps. Especially when I started (on purpose) with tomatoes. The reaction of the tomatoe juice alone enhances the edge wear on the blue2 petty in a bad way, making the difference in edge retention noticable even quicker.
Then I took of the pink glasses and started to read more about simple carbon steels...



A bit offtopic, dont want to hyjack...
Carbon steels with alloys (tungsten/vanadium), isn't that whats mostly ment with powder steel? Or is there an other difference aswell? Higher carbon %?
You name t15, 10v, zwear (which I never heared of) as examples and when naming powder steels mostly I see examples like sg2, hap40, zdp189...
Not naming those let me think powder steel is different from what you name high alloy cabon steel.

Could you explain?
 

M1k3

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Thx for clearing that up. TS is dealing with simple carbon steels if i read correctly.
I've got myself a blue2 petty a month ago, my first and only simple carbon steel knife. I was a bit dissapointed by the edge retention myself, compared to my aus10 SS gyuto. Ofcourse, the petty is much thinner, but I clearly notice a difference in edge wear, testing the same amount of veggies during the same diner preps. Especially when I started (on purpose) with tomatoes. The reaction of the tomatoe juice alone enhances the edge wear on the blue2 petty in a bad way, making the difference in edge retention noticable even quicker.
Then I took of the pink glasses and started to read more about simple carbon steels...



A bit offtopic, dont want to hyjack...
Carbon steels with alloys (tungsten/vanadium), isn't that whats mostly ment with powder steel? Or is there an other difference aswell? Higher carbon %?
You name t15, 10v, zwear (which I never heared of) as examples and when naming powder steels mostly I see examples like sg2, hap40, zdp189...
Not naming those let me think powder steel is different from what you name high alloy cabon steel.

Could you explain?
Stainless steel have more carbides (carbides=wear resistance) than simple carbon steels. Chromium and sometimes molybdenum carbides. Some even some small amounts of vanadium.

Powdered steel is a process. Can be used on stainless or carbon steels. The benefit of this process is keeping carbide sizes (big carbides= low toughness) from getting to big.

The steels I named aren't stainless. SG2/R2, hap40, zdp189 (SemiStainless btw) are powdered steels.

Regarding the tomato, acids erode carbon steels slowly. Stainless, followed by SemiStainless, is well suited for acidic stuff.
 

Kawa

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Stainless steel have more carbides (carbides=wear resistance) than simple carbon steels. Chromium and sometimes molybdenum carbides. Some even some small amounts of vanadium.

Powdered steel is a process. Can be used on stainless or carbon steels. The benefit of this process is keeping carbide sizes (big carbides= low toughness) from getting to big.

The steels I named aren't stainless. SG2/R2, hap40, zdp189 (SemiStainless btw) are powdered steels.

Regarding the tomato, acids erode carbon steels slowly. Stainless, followed by SemiStainless, is well suited for acidic stuff.

Thx, appreciate it.
I have lots to learn about all the different steels and their properties.
It is a new chapter for me, which I find interesting. My head got stuck when I started reading about carbide sizes and their behaviour, soon you go into tempering and quenching, staring at all kind of diagrams o_O

Maybe during and after a nightshift isnt the best time to study this...
 

Nemo

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The first thing that I would exclude is that you have a residual wire edge.

I remember when I satarted out, I was pretty happy with my edges fresh off the stones. However, my edges improved dramatically (both in terms of sharpness and retention) when I realised that most of the effort (by far) in sharpening is expended on burr control and removal rather than burr formarion.

Can you describe in detail how you develop your apex and remove the burrs?

Which steels are you sharpening?

I agree that the temptation to use too fine a grit can be problematic, especially for the new sharpener.
 

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Talking about edge retention is so hard because there is really no standard on what good edge retention is when it comes to kitchen knives in particular or what sharp is. So much depends on what you call sharp and what you call dull. There are just so many variables when it comes to kitchen knives. Comparing purely steels is very hard, but easier and the best has been done by @Larrin in knifesteelnerds articles. Some argue that cutting media makes a difference and that if using a different media the simpler steels would show more of a variance among them. This might or might not be true and would be interesting to try. One of the problems is that we don't have very many kitchen knives with high alloy steels, so experience with them is limited. Another problem is that many people don't use correct abrasives when sharpening high alloy steels and don't have enough experience with them to get them sharp. Low alloy steels are just easier to get sharp and burr free.

One of the other interesting questions is if the geometry, sharpening angle, and grid should be different depending on the steel. It is unlikely that even makers that use different steels adjust geometry based on the steel they use for a particular knife.
 

M1k3

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Thx, appreciate it.
I have lots to learn about all the different steels and their properties.
It is a new chapter for me, which I find interesting. My head got stuck when I started reading about carbide sizes and their behaviour, soon you go into tempering and quenching, staring at all kind of diagrams o_O

Maybe during and after a nightshift isnt the best time to study this...
Check out knifesteelnerds.com
Don't worry about temperatures and that stuff. That's aimed at makers, not knife users.
 

ModRQC

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Edge consistency could be a culprit - different angles used, usually found near the heel, where the knife has most curve, near the tip. Creates a weird shift in the edge, sometimes easy to see with the eye (edge bevel). Will cut pt after sharpening because that's as keen as you'll get it but after one prep you don't have that keen out of the stone apex quite anymore, and an inconsistent edge won't show with most food, but paper towel isn't forgiving.

It doesn't tolerate a burr remnant either. Sometimes you get the "phantom" burr. Check as you do when sharpening after the first prep meal. You might find out that there some part of a burr that is still clinging there.

I don't even test on pt much anymore out of the stones. As someone said, setting too high expectations could be a culprit. Cut some paper to make sure I didn't fail anything, move onto food asap, won't know before I've cut some produces. Moreover I don't care using a lot of bamboo boards with all my knives, and don't expect the very absolutely keen edge to keep going long. I've been satisfied with my work when I can do a lot of easy preps on what cutability is left once fresh keenness is gone.
 

Matt Jacobs

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I agree with many of the above answers (not that my opinions really matter vs many of the experts here) I would lead towards a wire edge if you are losing the sharpness that fast. I also might question going any higher than 4-5k on a stone. If I do my 800 grit stone and strop I cut paper cleanly but struggle through paper towel. I have a really nice toothy edge that loves tomatoes and will last a long time just by stropping after use. If I go 800-5k then strop I get a screaming sharp edge. Cleanly through paper towel, shaving the hair off my tattoos etc. I find that after a couple of uses and stroping though that I lose any toothiness and can struggle a bit through tomatoes or peppers. I dont use the same progression through each of my knives either. I like taking white steel to my 5k. AS steel I think I like better stopping at 800 and stropping. I would say its ok to treat each knife differently and think about what you are cutting. Do you need more toothiness or a shaving sharp edge etc. Again make sure the burr is gone..
 
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