# edge retention after sharpening



## Goorackerelite (Oct 1, 2020)

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 ?


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## Dhoff (Oct 1, 2020)

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.


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## Rangen (Oct 1, 2020)

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.


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## PappaG (Oct 1, 2020)

Based strictly on your post, expectations are too high IMHO. You knife continues to perform, right?


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## M1k3 (Oct 1, 2020)

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.




 @TSF415


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## Hz_zzzzzz (Oct 1, 2020)

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.


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## Carl Kotte (Oct 1, 2020)

There’s no upper limit to How many meals you can prep with a denka and still slice towel.


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## PappaG (Oct 1, 2020)

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...


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## Hz_zzzzzz (Oct 1, 2020)

Carl Kotte said:


> There’s no upper limit to How many meals you can prep with a denka and still slice towel.


Unbelievable but satisfying answer. Thank you! Now my expectation for my denka is sky high.


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## M1k3 (Oct 1, 2020)

Hz_zzzzzz said:


> Unbelievable but satisfying answer. Thank you! Now my expectation for my denka is sky high.


If you lower your expectations, you'll be more impressed.


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## kayman67 (Oct 1, 2020)

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.


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## Hz_zzzzzz (Oct 1, 2020)

PappaG said:


> 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 (


https://www.bilibili.com/video/BV17E411J79n/


). 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 (Oct 1, 2020)

Goorackerelite said:


> 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. (A_ssuming 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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## inferno (Oct 1, 2020)

almost no steels keep that fresh off the stones sharpness for more than like 10 minutes. its just how it works.


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## Benuser (Oct 1, 2020)

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.


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## Jason183 (Oct 1, 2020)

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.


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## Kawa (Oct 1, 2020)

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?


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## BillHanna (Oct 1, 2020)

Jason183 said:


> 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


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## kayman67 (Oct 1, 2020)

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


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## M1k3 (Oct 1, 2020)

Kawa said:


> 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?
> 
> 
> ...


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.


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## Kawa (Oct 1, 2020)

M1k3 said:


> 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?


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## M1k3 (Oct 1, 2020)

Kawa said:


> 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...
> 
> ...


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.


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## Kawa (Oct 1, 2020)

M1k3 said:


> 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.
> 
> ...




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 

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


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## Nemo (Oct 1, 2020)

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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## Barmoley (Oct 1, 2020)

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.


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## TSF415 (Oct 1, 2020)

@M1k3 You let me down. You had a great opportunity to post a video. lol


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## M1k3 (Oct 1, 2020)

Kawa said:


> 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
> 
> 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.


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## ModRQC (Oct 1, 2020)

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.


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## HSC /// Knives (Oct 2, 2020)

Try a z wear steel blade.


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## Matt Jacobs (Oct 2, 2020)

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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## ref (Oct 3, 2020)

I had a problem with edge retention for a few months.

It turned out the green scourer I was using to clean my knives had aluminum oxide in (and I assume then all green scourers do). I was essentially cleaning my knife with metal. So if you're having problems with edge retention make sure you're cleaning/drying/storing your knives properly (soft sponge with hot water -> dry with a good towel -> store)


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## dglevy (Oct 3, 2020)

Someone in one of these forums pointed out that the main reason knives get dull is the cutting board. I took that to heart and have been (1) using cutting boards with soft wood (e.g. pine, redwood, red cedar), and (2) trying not to slam into the cutting board. My knives (mostly Tojiros and one Randy Haas 240 gyuto) are not hair popping sharp but plenty sharp, and I don't do a lot of chopping, but they have stayed pretty much the same for years, now--no need to re-sharpen...


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## captaincaed (Oct 4, 2020)

ref said:


> I had a problem with edge retention for a few months.
> 
> It turned out the green scourer I was using to clean my knives had aluminum oxide in (and I assume then all green scourers do). I was essentially cleaning my knife with metal. So if you're having problems with edge retention make sure you're cleaning/drying/storing your knives properly (soft sponge with hot water -> dry with a good towel -> store)


This is an underappreciated, hidden issue. Buy only blue scrubbies (no abrasive), burn the green ones. 

Also think about reading Larrin's articles on abrasion resistance. That'll give you a sense of where steels stack up.

If it's early in your sharpening career, take an honest look at deburring as well.

Is OP still here?


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## juice (Oct 4, 2020)

captaincaed said:


> Is OP still here?


Doesn't matter, that's one of the great things about forums.


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## nakiriknaifuwaifu (Oct 4, 2020)

BillHanna said:


> Reading this over and over again has saved my future wallet hundreds of dollars.
> 
> God bless us, everyone!
> 
> ...



My $0.02: Gesshin 2k and high grit Jnat to strop 

the G2k was my favorite stone when I went to JKI. 

I have the cerax 1k and 3k, the 3k is really sweet too.


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## captaincaed (Oct 4, 2020)

juice said:


> Doesn't matter, that's one of the great things about forums.


Buncha dogs chasing our tails


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## juice (Oct 4, 2020)

captaincaed said:


> Buncha dogs chasing our tails


Who us?

Really though, the OP could return tomorrow and learn it. Even if he doesn't, others of us out here are learning it anyway. Likewise someone who lands here after a search.

Very useful things, forums. So far ahead of FB or Discord it's ridiculous.


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## M1k3 (Oct 5, 2020)

juice said:


> Who us?
> 
> Really though, the OP could return tomorrow and learn it. Even if he doesn't, others of us out here are learning it anyway. Likewise someone who lands here after a search.
> 
> Very useful things, forums. So far ahead of FB or Discord it's ridiculous.


And we all see the same thing instead of what some software thinks we should see.


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## juice (Oct 5, 2020)

M1k3 said:


> And we all see the same thing instead of what some software thinks we should see.


Exactly right.


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## Carl Kotte (Oct 5, 2020)

What do we see? I see nothing (since 1781)


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## M1k3 (Oct 5, 2020)

Carl Kotte said:


> What do we see? I see nothing (since 1781)


Said the taxidermist.


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## juice (Oct 5, 2020)

Carl Kotte said:


> What do we see? I see nothing (since 1781)


Wasn't the Lion from 1731?


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## Carl Kotte (Oct 5, 2020)

juice said:


> Wasn't the Lion from 1731?


We decided to make the Lion more contemporary by moving him 50 years closer to the present. Immer aktuell!


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## BillHanna (Oct 5, 2020)

nakiriknaifuwaifu said:


> My $0.02: Gesshin 2k and high grit Jnat to strop
> 
> the G2k was my favorite stone when I went to JKI.
> 
> I have the cerax 1k and 3k, the 3k is really sweet too.


How dare you. I know your tricks, mariachi. I will NOT enter the Jnat rabbit hole. Get theee behind me, satan.


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## Ruso (Oct 5, 2020)

Carl Kotte said:


> We decided to make the Lion more contemporary by moving him 50 years closer to the present. Immer aktuell!


That’s a Lion!? O my, All this time I thought it was a hand puppet from a horror show!


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## Barmoley (Oct 5, 2020)




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## Bert2368 (Oct 5, 2020)

Er. Everything I was going to say has been said. Then blind time traveling lions showed up and ate the OP?


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## M1k3 (Oct 5, 2020)

Bert2368 said:


> Er. Everything I was going to say has been said. Then blind time traveling lions showed up and ate the OP?


That's taxidermied blind time traveling lions...


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## Bert2368 (Oct 5, 2020)

M1k3 said:


> That's taxidermied blind time traveling lions...


The additional informationd did not help my tenuous grasp of reality one bit.


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## FishmanDE (Oct 5, 2020)

You're either here for a good time or a long time.


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## dglevy (Oct 6, 2020)

ref said:


> I had a problem with edge retention for a few months. It turned out the green scourer I was using to clean my knives had aluminum oxide in (and I assume then all green scourers do). I was essentially cleaning my knife with metal. So if you're having problems with edge retention make sure you're cleaning/drying/storing your knives properly (soft sponge with hot water -> dry with a good towel -> store)





captaincaed said:


> This is an underappreciated, hidden issue. Buy only blue scrubbies (no abrasive), burn the green ones.
> Also think about reading Larrin's articles on abrasion resistance. That'll give you a sense of where steels stack up. If it's early in your sharpening career, take an honest look at deburring as well.
> Is OP still here?



Wow, I had no idea! As an experiment, I just scrubbed off the accumulated patina on my Randy Haas 240 gyuto, and it left score marks on the blade--might as well be steel wool. Thanks for mentioning that. Green will be dutifully burned from now on...

Could you post a link to what you think is the best Larrin article? I'm kinda curious to see what the state of steels is, these days. I've been off the forums for a good 5 or 6 years, at this point. (Rip van Winkle awakes... I've been wanting to replace the Randy Haas ever since I got it. Food sticks too easily to it; it doesn't happen as much with my Tojiro 210 but I like the thinner, longer blade of the Randy Haas.)


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## Barmoley (Oct 7, 2020)

The most comprehensive and extensive testing of steels is Testing the Edge Retention of 48 Knife Steels - Knife Steel Nerds

The most relevant to many discussions is 13 Myths about Heat Treating Knives - Knife Steel Nerds

In reality, all Larrin's articles should be read as they build on each other and give you fuller understanding of steels, etc.


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## captaincaed (Oct 7, 2020)

The Knife Talk Podcast recently interviewed Larrin as well. You can learn a lot from that episode, and it's a cool way to get a sense of his personality.

I'm not sure there are really new steels per se, maybe the 1.2xxx German steels, but they often have analogues to the Japanese steels. Not an exact match, but I think you get pretty close. Aussie makers seem to be using them.


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## dglevy (Oct 8, 2020)

Barmoley said:


> The most comprehensive and extensive testing of steels is Testing the Edge Retention of 48 Knife Steels - Knife Steel Nerds
> The most relevant to many discussions is 13 Myths about Heat Treating Knives - Knife Steel Nerds
> In reality, all Larrin's articles should be read as they build on each other and give you fuller understanding of steels, etc.





captaincaed said:


> The Knife Talk Podcast recently interviewed Larrin as well. You can learn a lot from that episode, and it's a cool way to get a sense of his personality.
> I'm not sure there are really new steels per se, maybe the 1.2xxx German steels, but they often have analogues to the Japanese steels. Not an exact match, but I think you get pretty close. Aussie makers seem to be using them.


Thanks for the links! I look forward to the deep dive 

Interesting that the Germans have finally figured out that a higher HRC is a good thing...


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## Barmoley (Oct 8, 2020)

dglevy said:


> Thanks for the links! I look forward to the deep dive
> 
> Interesting that the Germans have finally figured out that a higher HRC is a good thing...


Higher HRC is not necessarily a good thing. Depends on your application and steel. It is just something that can be easily measured and gives you some idea about one aspect of the steel and an idea of performance if you know what the steel is and fully understand your use case.


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## dglevy (Oct 8, 2020)

I thought, as long as the blade has a decent level of toughness, the higher the HRC, the better. For my particular application, it seems to me that the edge retention that comes from hardness is what matters most. I only use my knives for light duty at home: veggies, fruit, meats. I don't hack bones with them and I don't cut hard things like butternut squash. In the 10 years I've been using my Tojiros and 6 years, the Randy Haas, I've never chipped an edge. But, as Dennis Miller supposed, "that's just my opinion, I could be wrong"


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## Barmoley (Oct 8, 2020)

dglevy said:


> I thought, as long as the blade has a decent level of toughness, the higher the HRC, the better. For my particular application, it seems to me that the edge retention that comes from hardness is what matters most. I only use my knives for light duty at home: veggies, fruit, meats. I don't hack bones with them and I don't cut hard things like butternut squash. In the 10 years I've been using my Tojiros and 6 years, the Randy Haas, I've never chipped an edge. But, as Dennis Miller supposed, "that's just my opinion, I could be wrong"


You just can't generalize like that. What's decent level of toughness? Which steel are you talking about? Some steels loose a lot of toughness as they become harder, some don't loose as much. What is your geometry like? You can chip pretty much any steel if you make it hard enough and your edge is thin enough. I've seen knives micro chip from cutting apples and hitting apple pits or lemon pits, so doesn't have to be anything really hard. Is your technique perfect and you never have any lateral load on the edge? What is your board like? I can go on and on, but the point I am trying to make is that you can't generalize that higher HRC is always better. It is just one number that is very overused. This reminds me Rockwell Hardness is the Megapixels of Knife Steel Specs - Knife Steel Nerds


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## ian (Oct 8, 2020)

dglevy said:


> I thought, as long as the blade has a decent level of toughness, the higher the HRC, the better. For my particular application, it seems to me that the edge retention that comes from hardness is what matters most. I only use my knives for light duty at home: veggies, fruit, meats. I don't hack bones with them and I don't cut hard things like butternut squash. In the 10 years I've been using my Tojiros and 6 years, the Randy Haas, I've never chipped an edge. But, as Dennis Miller supposed, "that's just my opinion, I could be wrong"



Super hard steels are a pain to sharpen, and are more chippy. I don’t think Tojiros are very hard. 60 HRC, perhaps? That’s the soft side of J knives, fyi. Don’t know about your Haas knife.

If you want to rock chop all day long and you don’t mind using a rod, a softer steel can be just fine. I’m happiest with medium hard J knives, eg 62-65, although of course it depends on the knife.


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## dglevy (Oct 8, 2020)

Barmoley said:


> You just can't generalize like that. What's a decent level of toughness? Which steel are you talking about? Some steels lose a lot of toughness as they become harder, some don't lose as much. What is your geometry like? You can chip pretty much any steel if you make it hard enough and your edge is thin enough. I've seen knives micro chip from cutting apples and hitting apple pits or lemon pits, so doesn't have to be anything really hard. Is your technique perfect and you never have any lateral load on the edge? What is your board like? I can go on and on, but the point I am trying to make is that you can't generalize that higher HRC is always better. It is just one number that is very overused. This reminds me Rockwell Hardness is the Megapixels of Knife Steel Specs - Knife Steel Nerds


I'm not generalizing to all people, I'm just saying, for my purposes, I like having a knife with a hard Japanese steel, for edge retention purposes, as opposed to, say, a Wuesthoff or Zwilling. I use soft wood cutting boards specifically to save the edge (pine, red cedar, redwood). My Tojiro DPs and the Randy Haas have performed amazingly well over 10 years of light use.


ian said:


> Super hard steels are a pain to sharpen, and are more chippy. I don’t think Tojiros are very hard. 60 HRC, perhaps? That’s the soft side of J knives, fyi. Don’t know about your Haas knife. If you want to rock chop all day long and you don’t mind using a rod, a softer steel can be just fine. I’m happiest with medium hard J knives, eg 62-65, although of course it depends on the knife.


Yes, according to my notes at the time, the Tojiro DPs are 60-61, the Randy Haas, also 60-61. Never had to use a rod, but I did re-sharpen them all at least once, maybe twice. 
That's astonishing to me that you call 62-65 'medium hard'. You mean to say there are knives out there that are harder than 65? YIKES!


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## ian (Oct 8, 2020)

dglevy said:


> I'm not generalizing to all people, I'm just saying, for my purposes, I like having a knife with a hard Japanese steel, for edge retention purposes, as opposed to, say, a Wuesthoff or Zwilling. I use soft wood cutting boards specifically to save the edge (pine, red cedar, redwood). My Tojiro DPs and the Randy Haas have performed amazingly well over 10 years of light use.
> 
> Yes, according to my notes at the time, the Tojiro DPs are 60-61, the Randy Haas, also 60-61. Never had to use a rod, but I did re-sharpen them all at least once, maybe twice.
> That's astonishing to me that you call 62-65 'medium hard'. You mean to say there are knives out there that are harder than 65? YIKES!



Yea, I’m mainly distinguishing them from the crazy hard knives that some makers put out. Certainly, 62-65 is pretty hard.


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## M1k3 (Oct 8, 2020)

dglevy said:


> I'm not generalizing to all people, I'm just saying, for my purposes, I like having a knife with a hard Japanese steel, for edge retention purposes, as opposed to, say, a Wuesthoff or Zwilling. I use soft wood cutting boards specifically to save the edge (pine, red cedar, redwood). My Tojiro DPs and the Randy Haas have performed amazingly well over 10 years of light use.
> 
> Yes, according to my notes at the time, the Tojiro DPs are 60-61, the Randy Haas, also 60-61. Never had to use a rod, but I did re-sharpen them all at least once, maybe twice.
> That's astonishing to me that you call 62-65 'medium hard'. You mean to say there are knives out there that are harder than 65? YIKES!


Sukenari AS, ZDP-189 and HAP-40 lines are some I can think of off the top of my head.


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## captaincaed (Oct 8, 2020)

dglevy said:


> Thanks for the links! I look forward to the deep dive
> 
> Interesting that the Germans have finally figured out that a higher HRC is a good thing...


_Alloyed _steels. They end up harder but the alloy is key


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## M1k3 (Oct 8, 2020)

captaincaed said:


> _Alloyed _steels. They end up harder but the alloy is key


Carbon also.


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## Southpaw (Oct 9, 2020)

When I changed to shaptons it solved this problem for me, I get better each time. I finish on a little natural and then polish it back up every ten days or so with diminishing returns each time and then after about 6 to 9 weeks later it’s time to go thru the progression again. This is thru primarily home use. (I also hone, however you need proper technique on that for it to be effective and not destroy your edge or even chip your knife). 

I think it has to do with expectations sometimes. I compare how long my edge lasted to the knife’s OTB and if it’s comparable I know I’m doing a good job.

Also what steel are you using? I find white 2 to lose its edge way quicker than blues. But it’s way easier to polish/hone. I’ve literally honed my white 2 back to passing sharpness tests after it couldn’t cut computer paper.


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## Kawa (Oct 9, 2020)

Southpaw said:


> When I changed to shaptons it solved this problem for me, I get better each time. I finish on a little natural and then polish it back up every ten days or so with diminishing returns each time and then after about 6 to 9 weeks later it’s time to go thru the progression again. This is thru primarily home use. (I also hone, however you need proper technique on that for it to be effective and not destroy your edge or even chip your knife).
> 
> I think it has to do with expectations sometimes. *I compare how long my edge lasted to the knife’s OTB and if it’s comparable I know I’m doing a good job.*
> 
> Also what steel are you using? I find white 2 to lose its edge way quicker than blues. But it’s way easier to polish/hone. I’ve literally honed my white 2 back to passing sharpness tests after it couldn’t cut computer paper.



I don't know if this is a meaningfull reference. From what i've read around here, the OOTB edge can be worse then a fresh, new edge. OOTB edges are often finished with powertools (a belt grinder goes also under the name 'hand finished', but we often think of wetstones when hearing hand finished). Sometimes the edge gets too hot and changes the effect of the original heat treatment. A OOTB edge might therefore be more chippy or does wear faster then after a sharpening (or 2).


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## Nemo (Oct 9, 2020)

dglevy said:


> I'm not generalizing to all people, I'm just saying, for my purposes, I like having a knife with a hard Japanese steel, for edge retention purposes, as opposed to, say, a Wuesthoff or Zwilling. I use soft wood cutting boards specifically to save the edge (pine, red cedar, redwood). My Tojiro DPs and the Randy Haas have performed amazingly well over 10 years of light use.



Edges can fail for a number of reasons:

1) The edge can roll over. This is the predominant mode of failure in softer steeled knives. The likelihood of this happening dependes on the hardness of the steel and the geometry just behind the edge (i.e.: the amount of steel supporting the edge. i.e.: the angle that the edge bevel is sharpened at).

2) The edge can chip. This is more likely with very hard, brittle steels, especially those sharpened to a very acute edge. Many of these steels are limited in the acuity of their edge angle by having a high carbide volume anyway.

3) The apex of the edge can be gradually abraded by food and the chopping board. @Larrin 's cardstock experiments have demonstrated that this is slower with an ACUTE edge angle. Hardness probably contributes somewhat to abrasion resistance but carbide volume (which in itself limits edge acuity) is much more important.

So in general, there are 3 strategies that can be used to maximise edge retention:

1) Soft steels in thick-edged (and thick behind the edge) knives. The edge fails by rolling and can be realigned with a "sharpening steel". These steels are often abrasion resistant and tough. Repeated realigning of the edge weakens the steel near the edge (work hardening/embrittlement, like a paperclip bent backwards and forwards over and over), so eventually the embrittled edge will chip. This tends to produce less well performing knives with the lowest overall edge retention but the most abuse resitance (which is why it is the stategy selected for mainstream knives).

2) Moderatelly hard steels (HRC 61-63?) made of simple steels with acute edges. Failure mode is by abrasion resistance as they generally don't roll over and are tough enough to not chip easily (depending on edge angle). This strategy produces the sharpest edges with moderate edge retention.

3) Highly alloyed hard steels (HRC 60-67): The more highly alloyed the steel, the more abrasion resistant but... the less acute an edge they can take (due to carbide volume causing carbide pull-out). These knives have a lower ultimate sharpness but generally longer edge retention than strategy 2. The harder these steels get, the more brittle they are and the more prone to the edge chipping. This strategy produces fairly sharp edges with generally the longest edge retention.

This is obviously a continuum And many knives will have a foot in two camps.

So hardness does affect edge retention, but the how is complex and it is nowhere near as straightforward as "harder is better".


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## Benuser (Oct 9, 2020)

A factory edge isn't necessarily meant to be used as such. A too fine an edge allows you to put your own on it with a few strokes only, but wouldn't survive the first board contact. If you get a Honesuki with an inclusive angle of 12° don't believe you're dealing with a miraculous steel. Rather get your stones.


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## dglevy (Oct 9, 2020)

Nemo said:


> Edges can fail for a number of reasons:
> 1) The edge can roll over. This is the predominant mode of failure in softer st<snip>


Thanks for the summary! Makes a lot of sense to me, and makes me even more satisfied with my knives, which are 60-61 HRC, apparently and have held their edges for far longer than I expected them to. I wonder about the very hard alloyed steels. They must be hard to sharpen. I mean, they must require a lot of elbow grease and numerous passes, no?


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## ModRQC (Oct 9, 2020)

Increased wear resistance... as @inferno so aptly put a couple of times on different occasions it’s a tradeoff of time on the stones vs. time the edge endures. That being said, if you don’t use a lot of slicing motion, and don’t cut into the cutting board any chance you get, there’s not a lot of need for wear resistance and no problem whatsoever for a simple carbon to retain it’s edge for some time.


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## M1k3 (Oct 9, 2020)

dglevy said:


> Thanks for the summary! Makes a lot of sense to me, and makes me even more satisfied with my knives, which are 60-61 HRC, apparently and have held their edges for far longer than I expected them to. I wonder about the very hard alloyed steels. They must be hard to sharpen. I mean, they must require a lot of elbow grease and numerous passes, no?


Yes and no. Regular water stones would choke or be really slow. Diamond stones don't care about the alloy or hardness.


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## kayman67 (Oct 10, 2020)

dglevy said:


> Thanks for the summary! Makes a lot of sense to me, and makes me even more satisfied with my knives, which are 60-61 HRC, apparently and have held their edges for far longer than I expected them to. I wonder about the very hard alloyed steels. They must be hard to sharpen. I mean, they must require a lot of elbow grease and numerous passes, no?


If you use the wrong tools for the job, yes. Today we have quite good different types of bonds for diamond and cbn (unfortunately cbn still really expensive).


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## Benuser (Oct 10, 2020)

ModRQC said:


> Increased wear resistance... as @inferno so aptly put a couple of times on different occasions it’s a tradeoff of time on the stones vs. time the edge endures. That being said, if you don’t use a lot of slicing motion, and don’t cut into the cutting board any chance you get, there’s not a lot of need for wear resistance and no problem whatsoever for a simple carbon to retain it’s edge for some time.


Wear resistance is a factor in edge retention, but no guarantee. Many crappy soft stainless have a spectacular wear resistance but a poor edge retention due to the lack of edge stability resulting from large, poorly distributed or clustering chromium carbides. More advanced, hard stainless have a much better edge retention but do not take or hold the finest edges.


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## Nemo (Oct 10, 2020)

dglevy said:


> Thanks for the summary! Makes a lot of sense to me, and makes me even more satisfied with my knives, which are 60-61 HRC, apparently and have held their edges for far longer than I expected them to. I wonder about the very hard alloyed steels. They must be hard to sharpen. I mean, they must require a lot of elbow grease and numerous passes, no?



No problem.

I should point out that your Tojiros (VG10) are actually fairly highly alloyed steels, even if their hardness is moderate (62ish IIRC). They are more in group 3 than group 2. Remember that it's not only the hardness but also the carbide volume (degree of alloyimg elements) that's important. So they won't take a super acute edge (but will take a more acute edge than a Wustoff) but will have a decent edge retention. The other issue with some highly alloyed steels (especially VG10 ) is that they require a bit more effort to fully deburr (says the guy who has never actually sharpened VG10 ).

A lot of the more highly alloyed steels (especially PM steels like SG2/R2 SRS15, HAP40 and even ZDP) are a little more difficult to grind, but not that much more. IME, the difficulty lies more in the deburring than the sharpening.

There are certainly some steels that are truly difficulcult to grind, but you don't often see them in kitchen knives (Niolox perhaps being the exception).


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## Benuser (Oct 10, 2020)

Please note the somewhat bizarre dulling curve with VG-10: fresh from the stones, sharp like hell. Dulling very quickly to a moderate level of sharpness that will be sufficient in everyday Western cuisine where it stays almost forever.


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## Sailor (Oct 10, 2020)

I’ve agonized over edge retention for several years, it’s a riddle I don’t think I can solve. As sharpeners all we can do is ensure that the edge is clean, thin behind the edge and sharpened an an angle appropriate for the steel. Finishing grit seems to play a role but I’m ignorant of the science behind that. I rarely finish a soft knife finer than 1.5-2k but again, it’s influence on edge retention is a mystery to me personally. I no longer fret about it because once the knife is out of my hands it often falls prey to poor steeling technique, inappropriate storage, slamming the edge on a hard cutting board, using the edge to scrape food off that board. I do what I can with every knife and make sure I educate folks on their role in edge retention. I manage expectations and just do my part.


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## Southpaw (Oct 10, 2020)

Kawa said:


> I don't know if this is a meaningfull reference. From what i've read around here, the OOTB edge can be worse then a fresh, new edge. OOTB edges are often finished with powertools (a belt grinder goes also under the name 'hand finished', but we often think of wetstones when hearing hand finished). Sometimes the edge gets too hot and changes the effect of the original heat treatment. A OOTB edge might therefore be more chippy or does wear faster then after a sharpening (or 2).


Oh yes this a good point, only works with knives with a great ootb edge from a great sharpener I’m sorry I should’ve said that...


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## Kawa (Oct 10, 2020)

Sailor said:


> I’ve agonized over edge retention for several years, it’s a riddle I don’t think I can solve. As sharpeners all we can do is ensure that the edge is clean, thin behind the edge and sharpened an an angle appropriate for the steel. Finishing grit seems to play a role but I’m ignorant of the science behind that. I rarely finish a soft knife finer than 1.5-2k but again, it’s influence on edge retention is a mystery to me personally. I no longer fret about it because once the knife is out of my hands it often falls prey to poor steeling technique, inappropriate storage, slamming the edge on a hard cutting board, using the edge to scrape food off that board. I do what I can with every knife and make sure I educate folks on their role in edge retention. I manage expectations and just do my part.



Last week I returned a knife to a friend of mine, explaining some basis things on how to keep it sharp for as long as possible: no dishwasher, not in the drawer etc...
His wife came home and before I could protest she was like: 'ah great, the knife is back. The kitchen machine broke down this afternoon and I want to make a cake with a bottom of scrumbled nuts. Glad I can use the knife now!'

but but but but......

Before I could even respond she started chopping and smashing the nuts and this went on for about an hour...


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## ModRQC (Oct 10, 2020)

I can imagine you attempting to hold a discussion with your friend and cringing every few « snap, crack and ziiiing »


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## M1k3 (Oct 10, 2020)

Kawa said:


> Last week I returned a knife to a friend of mine, explaining some basis things on how to keep it sharp for as long as possible: no dishwasher, not in the drawer etc...
> His wife came home and before I could protest she was like: 'ah great, the knife is back. The kitchen machine broke down this afternoon and I want to make a cake with a bottom of scrumbled nuts. Glad I can use the knife now!'
> 
> but but but but......
> ...


Did they still have the shells on? Rock-walking-scrape-chop?


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## Kawa (Oct 10, 2020)

ModRQC said:


> I can imagine you attempting to hold a discussion with your friend and cringing every few « snap, crack and ziiiing »



I took out my hearing devices (I really wear them) and that solved that problem


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## Kawa (Oct 10, 2020)

M1k3 said:


> Did they still have the shells on? Rock-walking-scrape-chop?



Don't know, I was afraid to go over and look, knowing I can't resist to comment on the abuse in her territory


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## ian (Oct 10, 2020)

If it’s a middle of the road knife I’d be fine with her chopping nuts with it. It’s gonna get used! Guess you might want them to appreciate the off the stones sharpness a little more, but...


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## Nemo (Oct 10, 2020)

Sounds like a good situation to use a microbevel.


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## Kawa (Oct 10, 2020)

You are right. I know people hand wash it for 2 days and then put it back in the dishwasher... You are into knives or not..

At the end they are doing me a favor by letting me sharpen their knives. I wouldn't get better if I can't get my hands on enough knives from friends & family.
And they know I look at it this way.


My crying and making fun of the abuse comes with a grain of salt 

(Responding to @ian )


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## Kawa (Oct 10, 2020)

Nemo said:


> Sounds like a good situation to use a microbevel.



I think the microbevel needs a microbevel to survive that


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## M1k3 (Oct 10, 2020)

Nemo said:


> Sounds like a good situation to use a macrobevel.


FTFY


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## augerpro (Oct 11, 2020)

I think wire edges are the first stumbling block people run into when they finally learn how to get a super sharp edge. I know it was for me. Echoing others above, burr removal is the most important step to a long lasting edge. After a very long path of trying different techniques, the following is my current method and I'm finally very satisfied. I need only sharpen every six months or so in a home kitchen. I should mention what really pushed my method to what it is now is the scienceofsharp.com tests. Once you could actually see what was happening at the edge with different techniques, you could start to understand the mechanism and that takes the voodoo out of it - which required tons of experience to arrive at a good method.

1) edge-leading strokes on 1k Shapton GS stone
2) strop on 1k stone. *I've changed this a lot over the years too, I now only do about 3-4 strokes then switch sides, then drop to 1 stroke and flip back and forth. There is a high risk of over-doing stropping and actually creating a wire edge. The real goal is to weaken and remove the burrs, and I think flipping back and forth doing only one stroke helps with this.
3) strop on 1.0 micron diamond spray loaded kangaroo leather. Technique just like above.
4) edge-leading strokes on 4k Shapton GS
5) strop on 4k stone as above
6) strop on 0.5 micron diamond spray loaded kangaroo strop as above

Over-doing any of the steps above is a problem. Experiment with the stropping pressure for the loaded leather step. I typically use just a bit of pressure after stropping the 1k stone, but very little on the final strop. I no longer pull through cork after seeing the results at scienceofsharp. Yes it removes the burr well, but also just yanks chunks out of the edge. working against the work you've just done.

I've also always inspected the edge with one of those cheap little microscopes and I've now been able to correlate what I see with the long edge retention. It's important that you hold the microscope with the light on the bottom as shown below. What I've noticed is that when the edge just disappears into the blackness, the burr and any "frays" are gone and it will last a long time. If you see the edge lit up, the burr is still there and will fold and deform, shortening the service life. I should mention that years ago when I focused on stropping, I often overdid it and the knife wouldn't bite into vegies (I was also finishing at 8k Shapton GS too). In that case - I don't really remember - I probably had removed that lit up burr in the microscope but had over-smoothed or even rounded the edge. So the trick is to find the stropping technique that removes that lit up edge with the fewest strokes and least amount of pressure. The key is doing just enough to pull the little jaggies off the edge, and have a nice straight apex that you see in the scienceofsharp photos.

*the knife below is used, not freshly sharpened, but it illustrates what I look for at the edge


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## knspiracy (Oct 24, 2020)

Goorackerelite said:


> how do I get that mythical edge retention that people are talking about?


I'm new to sharpening (about 20-25 sessions), and with a weekly sharpen - having an AO super steel core and a soft cutting board is all i need to retain edge. I've only ever had one Japanese knife and only for about 6 weeks so take my word with a grain of salt.
I cook and prep with an apprentice (so I do the bulk of the work) for 90 people daily and this new blade shaves hair all week without a touch up on a single stone.
Avoid rock chopping, or at least heavy rock chopping. Don't use honing rod. Maybe whack it on a strop during a particularly heavy day.
End of the week - 10 mins on 1000 grit and 5 mins on a 3000. Then I have a laser for the beginning of the next week to last 5 more days. The edge lasts plenty.

Burr removal may be the culprit or not maintaining same angle during sharpening..?


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