Edge dull too fast?

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I have been recently doing a lot of sharpening, changing my techniques, learning from JKI's playlist. I usually go from SP1000, then ouka 3000, depends on the steel type I might do some light stroke against a SP5000, and use a leather strop to finish them off. The edge bevel is usually below 15 and I use a Hasegawa FSB for chopping. I have been able to clean cut paper towels with the fresh edges, something that I wasn't able to do before, but it cuts like a dream. But seemingly just after one cutting session, the edge would struggle against paper towel, and after couple more they would not able to chop tomatoes into very thin slices smoothly as they do with fresh edges. The knives would not go straight through tougher pepper and roma tomatos without some slight gliding, other thins cuts just fine though.
Is something wrong with my techniques or is it my expectation too high? Seems to me the edge dulls rather quickly against tough skins, I can bring them back with quick stropping but I do hope for more.
 
Rapid dulling has often to do with incomplete deburring. The remaining burr breaks off and leaves a moonscape-like edge behind. Or it folds over the edge and makes it perfectly dull, as happens with soft steel. Tell us which knives are concerned. Do you deburr after every stone in the progression, and how do you deburr?
 
I'll second the burr problem... your comment that stropping brings back the edge really makes me think that's what is going on.

Often when people get to the point they are holding consistent angles they end up with what is often referred to here as a wire edge (it has been debated whether it exists or if it is the correct term...but I'm a believer because it happened to me a while back...)

When it happens...very carefully feel the edge to see if you can feel it rounded over...check it the way you'd feel for a burr while sharpening...you feel it... then you need to look into burr removal techniques... fortunately there are several methods you can easily find on here...find the one that works for you...

Should that not be the case...try finishing on a 1k ish stone see if the issue persists...there is an outside chance that when you hit the higher grits you are over working or over refining the edge and your technique needs adjusting...

Let us know how it works out...

Take care

Jeff
 
What kind of knife and steel?

Sounds most likely that you're not deburring properly. Possibly over doing it or not doing it right on the higher grits.

For tomatoes, I also find an edge around the 1k grit mark works best.
 
Steel? What kind of cutting surface? Chopping motion used? How extensive the cutting session?

Obviously burr is probably the problem, but still, these above variables should be made clear so that we can assess the particular situation each time someone asks that.
 
Thanks for all the advices!
Steel? What kind of cutting surface? Chopping motion used? How extensive the cutting
I seems have more problems with white #2, Aeb-l and 52100 while SKD12 and R2 are ok. I use hasegawa FSB cutting board, mainly push cut, some chopping with white#2 nakiri. The chopping sessions aren’t long, just cutting whole carrot into sticks, some tomato and mushrooms.
 
Rapid dulling has often to do with incomplete deburring. The remaining burr breaks off and leaves a moonscape-like edge behind. Or it folds over the edge and makes it perfectly dull, as happens with soft steel. Tell us which knives are concerned. Do you deburr after every stone in the progression, and how do you deburr?
I deburr after each progression, just light edge trailing strokes until I can’t feel the burr.
 
Thanks for all the advices!

I seems have more problems with white #2, Aeb-l and 52100 while SKD12 and R2 are ok. I use hasegawa FSB cutting board, mainly push cut, some chopping with white#2 nakiri. The chopping sessions aren’t long, just cutting whole carrot into sticks, some tomato and mushrooms.

This would rule out deterioration from acidity, AEB-L obviously and even 52100 is not so readily dulling from it and if only a few tomatoes in a short session.... Of course all three steels are those that have lesser retention, but one short prep is not that.

What's more interesting is that "usually" you'd have more "difficulties" deburring SG2 or possibly SKD-12 than the other ones. So if a burr is your problem, it's probably something you do in the last where the simpler steels are more affected.

I meant to ask if you tested/remarked that this happened with segments of the edge only, or the whole edge goes downhill no matter what?

I deburr after each progression, just light edge trailing strokes until I can’t feel the burr.

I'd look into developping the edge leading deburring method. It COULD be that using trailing on the simpler steels you raise a very very small burr that would act very sharp for a very short time. MIGHT not happen with the other ones so readily, or not as prominently.

Try the following, sounds like you might be creating a wire edge. Kippington Deburring Video

Beware that this creates a micro bevel. You might lose control/track of it in the future if you don't remember or pay attention to it.
 
yeah no trailing! only time i do trailing is when i have really, really soft stones. otherwise NO!
i would guess edge trailing on a fast stone like a shapton. even if its a 5k will definitely result in a small wire edge/burr.

aeb-l and 52100 are good steels if ht'ed correctly. they should last for more than one session.
good steel will probably stay sharp for a whole shift right? isn't that the common standard?

so you are probably doing something wrong. you just have to figure out what.
 
A nail test or flex test pushes weak material over to one side. If the knife shaves in one direction only some burr is left.
 
The way I read the opening post, hes asking if its normal to loose that super fresh sharpness after 1 session.
I do agree that you have a serious high level of sharpness for a long time, but that really fresh sharpness?

I havent tested a paper towel test or cutting tomatoes the way in the movie after a small sesion, so i wouln't know if i'd be still able to do that.

I know for sure that my white and blue steel loose that fresh sharpness very fast when doing tomatoes in the first session. They hold up very sharp afterwards.

So more a question from my side aswell:
After lets say after 15-20 minutes of prep work (short session?), is all of yours knives still as sharp as fresh of the stone/strop?
 
The way I read the opening post, hes asking if its normal to loose that super fresh sharpness after 1 session.
I do agree that you have a serious high level of sharpness for a long time, but that really fresh sharpness?

I havent tested a paper towel test or cutting tomatoes the way in the movie after a small sesion, so i wouln't know if i'd be still able to do that.

I know for sure that my white and blue steel loose that fresh sharpness very fast when doing tomatoes in the first session. They hold up very sharp afterwards.

So more a question from my side aswell:
After lets say after 15-20 minutes of prep work (short session?), is all of yours knives still as sharp as fresh of the stone/strop?
Just 15-20 minutes it is fine, won't be able to slice paper towels but still able to cut newspaper no problem, but sometimes it seems to struggle with tomato skins if I just saw them horizontally, but using guillotine and glide works fine.
 
Just 15-20 minutes it is fine, won't be able to slice paper towels but still able to cut newspaper no problem, but sometimes it seems to struggle with tomato skins if I just saw them horizontally, but using guillotine and glide works fine.


....

Sounds most likely that you're not deburring properly. Possibly over doing it or not doing it right on the higher grits.

For tomatoes, I also find an edge around the 1k grit mark works best.

I'd consider this to be rather normal. I also always found SP5K to be able to give a magical "ghosting effect" to an edge, but not one that would perform with waxy skins ever so well.
 
I exclusively use edge trailing and have never experienced the issues you're having,
My advice would be to simplify your sharpening session as much as you can to find the real problem.
Maybe try something like this (with your white steel):

Use SP1000 to raise burr on one side then the other.
Use reduced pressure and edge trailing like Peter Nowlan or edge trailing like Jon (both work fine).
Try nail bite test and paper towel.
If successful, move on to SP5000. If not, continue with edge trailing.
With light pressure, sharpen both sides like you did on the SP1000.
Edge trailing.
Nail test and paper towel.
If successful, continue to next step. If not, continue edge trailing.
Strop with denim (NOT leather).

Just curious. How long can you use your R2 knife before they need a touchup?
 
I exclusively use edge trailing and have never experienced the issues you're having,
My advice would be to simplify your sharpening session as much as you can to find the real problem.
Maybe try something like this (with your white steel):

Use SP1000 to raise burr on one side then the other.
Use reduced pressure and edge trailing like Peter Nowlan or edge trailing like Jon (both work fine).
Try nail bite test and paper towel.
If successful, move on to SP5000. If not, continue with edge trailing.
With light pressure, sharpen both sides like you did on the SP1000.
Edge trailing.
Nail test and paper towel.
If successful, continue to next step. If not, continue edge trailing.
Strop with denim (NOT leather).

Just curious. How long can you use your R2 knife before they need a touchup?
Thank you! Will try, R2 last pretty long, I have a Takamura red handle and Kobayashi Kei, both would last at least a month before need any touch up, I don’t take them to high grit though like I do carbon steel.
 
Just curious. How long can you use your R2 knife before they need a touchup?

Good question indeed. Or the SKD-12 one for that matter? Carbide volume helps SP5K adopt a bit more toothiness than it does simpler steels.
 
Thank you! Will try, R2 last pretty long, I have a Takamura red handle and Kobayashi Kei, both would last at least a month before need any touch up, I don’t take them to high grit though like I do carbon steel.

I think I get it now. If you want AEB-L, W#2 or 52100 to adopt that kind of behavior, I just don't think SP5K cuts the deal. SG4K would much better. Or a much cheaper Ouka which is also oh so forgiving/wonderful of trail deburring or just any technique and levels of skills whatsoever.
 
I think I get it now. If you want AEB-L, W#2 or 52100 to adopt that kind of behavior, I just don't think SP5K cuts the deal. SG4K would much better. Or a much cheaper Ouka which is also oh so forgiving/wonderful of trail deburring or just any technique and levels of skills whatsoever.
Thank you for all the help, I tried finishing using light edge leading stroke just on sp1k and the result fresh edge while not as screaming sharp but last a lot better after couple sessions, seems I have work my techniques on higher stones alot more.
 
I exclusively use edge trailing and have never experienced the issues you're having,
My advice would be to simplify your sharpening session as much as you can to find the real problem.
Maybe try something like this (with your white steel):

Use SP1000 to raise burr on one side then the other.
Use reduced pressure and edge trailing like Peter Nowlan or edge trailing like Jon (both work fine).
Try nail bite test and paper towel.
If successful, move on to SP5000. If not, continue with edge trailing.
With light pressure, sharpen both sides like you did on the SP1000.
Edge trailing.
Nail test and paper towel.
If successful, continue to next step. If not, continue edge trailing.
Strop with denim (NOT leather).

Just curious. How long can you use your R2 knife before they need a touchup?
Thank you! Do you mind me asking why denim not leather?
 
Thank you! Do you mind me asking why denim not leather?

Because too fine an edge won’t help you. Denim is rough. SP5K + leather hoping to cut waxy skins even at home for a while is asking too much. You’re in the cutting delicate fish territory there. Not cutting into tomatoes about equally efficiently for 10 even short sessions.

Don’t forget: your results might elevate your awareness of sharp, yet sustainably such sharp is why we all still dream of the dream steel.
 
Because too fine an edge won’t help you. Denim is rough. SP5K + leather hoping to cut waxy skins even at home for a while is asking too much. You’re in the cutting delicate fish territory there. Not cutting into tomatoes about equally efficiently for 10 even short sessions.

Don’t forget: your results might elevate your awareness of sharp, yet sustainably such sharp is why we all still dream of the dream steel.
Thank you, that make sense.
 
I have been recently doing a lot of sharpening, changing my techniques, learning from JKI's playlist. I usually go from SP1000, then ouka 3000, depends on the steel type I might do some light stroke against a SP5000, and use a leather strop to finish them off. The edge bevel is usually below 15 and I use a Hasegawa FSB for chopping. I have been able to clean cut paper towels with the fresh edges, something that I wasn't able to do before, but it cuts like a dream. But seemingly just after one cutting session, the edge would struggle against paper towel, and after couple more they would not able to chop tomatoes into very thin slices smoothly as they do with fresh edges. The knives would not go straight through tougher pepper and roma tomatos without some slight gliding, other thins cuts just fine though.
Is something wrong with my techniques or is it my expectation too high? Seems to me the edge dulls rather quickly against tough skins, I can bring them back with quick stropping but I do hope for more.
It might not be technique, chopping tomato requires quite a toothy edge, and as @ModRQC said, it's close to the fish cutting territory.
Maybe the edge will be able to perform the way you wish it does fresh off the stone, but after a session or two the edge loses it's toothyness(toothiness? Is that even a word?)
I personally have not used the SP 5K but I've heard the edge it gives isn't the toothiest in the range, so that doesn't really help either!

For task like so, I like to test my edge with Murray Carter's three fingers test to feel how toothy the edge is.
If not, I strop on my Aizu/Morihei 4K to bring back the teeth instead of strop, I personally think strop is great, but they take away the teeth on your edge after repeatedly touching up with it couple times, stropping makes my knives' edge smooth, especially with compound, that's only my opinion though, a lot more has to consider of course.
 
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It might not be technique, chopping tomato requires quite a toothy edge, and as @ModRQC said, it's close to the fish cutting territory.
Maybe the edge will be able to perform the way you wish it does fresh off the stone, but after a session or two the edge loses it's toothyness(toothiness? Is that even a word?)
I personally have not used the SP 5K but I've heard the edge it gives isn't the toothiest in the range, so that doesn't really help either!

For task like so, I like to test my edge with Murray Carter's three fingers test to feel how toothy the edge is.
If not, I strop on my Aizu/Morihei 4K to bring back the teeth, I personally think strop is great, but they take away the teeth on your edge, stropping makes my knives' edge very smooth, especially with compound, that's only my opinion though, a lot more has to consider of course.
Might try leave the leather strop in the drawer for awhile, kind sucks I just bought a new one, thankfully not really expansive. I might use Ouka for finishing and stroping now. Thank you for the insight!
 
I dont have any problem losing too much teeth when stropping on leather per se.
Finishing some random stainless on 5k+ and 0,5 micron strop? Yes. Yeah, that will be slick. Too slick. Cuts one meal and after that you really have to initiate the first cut by pushing (too) hard.

But finishing on whetever stone and removing the final burr on 1 or 2 micron (leather), makes the knife perform better.

Make sure you use some kind of strop after stone finishing. You need to remove that last remnants of burr somehow. I feel like how good i deburr, after a strop the edge is always cleaner. So if that new leather one is your only one? I would use it.

Use the Ouka (I notice you have one?) and do the paper towel test. Then just do 3-4 passes per side on the leather (or other strop). Test again. Is it better? You removed burr. Is it worse? You might have rounded the edge too much or made it too slick.
Dont do 20 passes per side like you see some bushcraft-billy do on youtube.

This way you can 'measure' what your stropping is doing for you.

For me, the sweetspot seems to be 5-6 passes per side. After that, I loose too much teeth. Before that, the knife sometimes staggers/hesitate on paper towel or rips smoking paper (then rice paper). (deburring on stone is the hardest part for me. I can improve a lot here. Still, im getting better and doing an OK job lately.)
 
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I dont have any problem losing too much teeth when stropping on leather per se.
Finishing some random stainless on 5k+ and 0,5 micron strop? Yes. Yeah, that will be slick. Too slick. Cuts one meal and after that you really have to initiate the first cut by pushing (too) hard.

But finishing on whetever stone and removing the final burr on 1 or 2 micron (leather), makes the knife perform better.

Make sure you use some kind of strop after stone finishing. You need to remove that last remnants of burr somehow. I feel like how good i deburr, after a strop the edge is always cleaner. So if that new leather one is your only one? I would use it.

Use the Ouka (I notice you have one?) and do the paper towel test. Then just do 3-4 passes per side on the leather (or other strop). Test again. Is it better? You removed burr. Is it worse? You might have rounded the edge too much or made it too slick.
Dont do 20 passes per side like you see some bushcraft-billy do on youtube.

This way you can 'measure' what your stropping is doing for you.

For me, the sweetspot seems to be 5-6 passes per side. After that, I loose too much teeth. Before that, the knife sometimes staggers/hesitate on paper towel or rips smoking paper (then rice paper). (deburring on stone is the hardest part for me. I can improve a lot here. Still, im getting better and doing an OK job lately.)
Thank you, will do.
 
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