Trouble Sharpening a 10YO Sabatier Kitchen Knife

P

peanutaxis

Joined
May 7, 2023
Messages
29
Hi Guys,

Thanks in advance. I can sharpen my Wusthofs and Japanese knives pretty well but I'm struggling to sharpen a Sabatier 6'' chef's knife.
What keeps happening is that after it gets used even only a little bit it develops what I would describe as a burr on both sides. I assume that what is happening is that - because it is softer steel than I'm used to - I am not removing the burr properly; when I do my burr removal maybe the burr is just standing up straight and seeming sharp, but with use it just gets mashed down and so it feels like a burr on both sides. I am sharpening on a Sharpal 325->1200 diamond plate. The last time I sharpened it I increased the angle to 20° on each side and then did many - like 50 each side - of burr removal strokes, but only very lightly. But the problem still happened.

I'm wondering if what I'm doing wrong is that you really need to start burr removal strokes at sharpening pressure and then gradually reduce them, whereas I went straight to very light strokes. Or maybe I'm way off track.

Thanks for the help,
p
 
What sort of cutting surface is the knife being used on? Sounds like it's hard enough that it's flattening and mushrooming the apex of the edge. That would create the burr-like effect on both sides of the flattened apex. Either the steel near the edge is much too soft to be durable, or the cutting surface used is much too hard for the edge.

It's possible there is a standing burr, as you mentioned. But ordinarily, if it's there, it would more likely just get rolled to one side or the other.

A family member of mine used to use a paring knife to section an apple on a ceramic tile countertop, pressing the blade through until it smacked hard against the tile. And predictably, the edge would get that flattened, mushroomed apex as a result. But that's the only time I've seen that sort of damage on a knife's edge.
 
Last edited:
Obsessed with Edges said:
What sort of cutting surface is the knife being used on? Sounds like it's hard enough that it's flattening and mushrooming the apex of the edge. That would create the burr-like effect on both sides of the flattened apex. Either the steel near the edge is much too soft to be durable, or the cutting surface used is much too hard for the edge.

It's possible there is a standing burr, as you mentioned. But ordinarily, if it's there, it would more likely just get rolled to one side or the other.

A family member of mine used to use a paring knife to section an apple on a ceramic tile countertop, pressing the blade through until it smacked hard against the tile. And predictably, the edge would get that flattened, mushroomed apex as a result. But that's the only time I've seen that sort of damage on a knife's edge.
Click to expand...
Thanks OwE. Yes I checked with the owner and they say they are only using it on their end-grain wooden board and not their marble benchtops. I plan to re-sharpen and use it heavily in my kitchen and see what happens. Do you have an opinion on the angle I am using, given that the internet tells me that Sabatier is HRC = 54-56? Thanks.
 
peanutaxis said:
Thanks OwE. Yes I checked with the owner and they say they are only using it on their end-grain wooden board and not their marble benchtops. I plan to re-sharpen and use it heavily in my kitchen and see what happens. Do you have an opinion on the angle I am using, given that the internet tells me that Sabatier is HRC = 54-56? Thanks.
Click to expand...
I think for the time being, the angle you've chosen (20° per side) should be OK for most any kitchen knife in that hardness range.

Another thought occurred to me yesterday. If for some reason, the knife had previously experienced some heat damage to the steel, as by powered grinding or whatever, then weird issues like you described could be possible until the heat-damaged steel is finally ground away near the edge. I've had one or two knives with strange issues like this, with very unstable steel near the edge. It took many resharpenings over time (weeks or months) to get rid of the weakened steel at the edge, after which they finally started behaving normally in typical uses. So, if you continue to see this odd behavior from the edge, it might just take some time to sort it out.
 
In regards to stropping...
I find the steel and hardness mostly determine the pressure needed and abrasive type when stropping. For example, Bucks seem to develop a hard burr for me. I use more pressure and a higher angle the first couple of passes, always finishing with very little pressure and the exact or very close (+.2) to the edge angle to finish.
Some stainless burrs just fights you all the way.
 
I am now also having trouble on a modern Wusthof (@17° per side). Something I'm doing is wrong. I'm raising a burr on both sides, then gradually reducing pressure alternating sides, leading edge stroke. I'm even looking through a jewellers loupe and the edge looks very clean. But then the edge rolls over within a week of use. I can do hundreds of light leading edge strokes and the edge will still roll over.

I searched on google and came up with this thread from this forum. The only thing I can think of is that I am pressing quite hard to raise the initial burrs. I never thought that pressing hard would be a problem. This means that burrs are not what I thought they are - and that pressing harder raises a larger burr, weakening the apex material such that even when you apex that weaker material it is still weak and will just fold over. This is the only conclusion I can come up with.
C

Thread 'Very difficult to remove burrs'

I have been sharpening knives (all my own as I have about 180 knives) for a couple of years. About 40% are paper cutting, shaving sharp. Most of these are made of steels (usually high end steels) that form burrs that fragment and fall apart easily when I am trying to remove them. There are some exceptions that are made from more ductile steels also.

However, many of my knives form burrs that will not go away, no matter what I do. Some of the knives are made of steels such as ATS34, VG10, AUS8 and a variety of cheaper steels. I have watched many YouTube videos of how to solve this problem...
  • Like

Appreciate any further input.
 
SharpBits said:
Interesting. Maybe try a felt block for burr removal? Some chef knife shops sell them for this purpose.
Click to expand...
hmmm. I'm reluctant. Sounds like an unusual remedy. If others here don't need to do this I'd rather fix what I'm doing wrong.

One thing I notice is the burr seems to roll over most obviously on the curved tip of the knife. This fits with my theory that more pressure on the stone leads to more metal fatigue and a bigger burr because a curved part of the knife sees a LOT more pressure because there is a lot less in contact with the stone. Compare this with the straight belly of the knife where the pressure is spread along a good distance of the knife.
I'm really starting to think that [the odd echos I've heard here of] Cliff Stamp is right here.
 
SharpBits said:
You might have already seen this article at Science of Sharp: https://scienceofsharp.com/2024/02/03/seven-misconceptions-about-knife-burrs/
Click to expand...
Think I've seen it before but, from that article:

"A sharpening burr is the metal that remains outside of the sharpening triangle."

This is what I am now disagreeing with. And I am disagreeing with it because after I apex several times on both sides (with a conservative sharpening angles) I can - and have - done hundreds of very light burr minimising strokes at the same angle (I use an angle guide at the end of the stone to calibrate) and even looked at the edge with a loupe, and yet the edge still rolls over with normal kitchen use on timber chopping boards.

So I am forced to conclude that if you use too much force into the stone then, sure, you can shave off the part of the burr that is not in the triangle. But the part that is still in the triangle is weakened steel and so can still roll over later.

I am forced into this conclusion.
 
peanutaxis said:
Think I've seen it before but, from that article:

"A sharpening burr is the metal that remains outside of the sharpening triangle."

This is what I am now disagreeing with. And I am disagreeing with it because after I apex several times on both sides (with a conservative sharpening angles) I can - and have - done hundreds of very light burr minimising strokes at the same angle (I use an angle guide at the end of the stone to calibrate) and even looked at the edge with a loupe, and yet the edge still rolls over with normal kitchen use on timber chopping boards.

So I am forced to conclude that if you use too much force into the stone then, sure, you can shave off the part of the burr that is not in the triangle. But the part that is still in the triangle is weakened steel and so can still roll over later.

I am forced into this conclusion.
Click to expand...
I think you're on the right track in your conclusion. Heavy pressure applied when apexing is never good for the edge. I used to have trouble on plated diamond hones in particular, with that - they're very unforgiving with too much pressure used - and very difficult burrs will be the result. I do believe it overstresses the edge.

It's OK to apply pressure when setting new bevels. But make sure to back way off with the pressure when you get close to apexing, before the burr forms. Let the grit do the work, at a light touch, in that phase.
 
Last edited:
Obsessed with Edges said:
I think you're on the right track in your conclusion. Heavy pressure applied when apexing is never good for the edge. I used to have trouble on plated diamond hones in particular, with that - they're very unforgiving with too much pressure used - and very difficult burrs will be the result. I do believe it overstresses the edge.

It's OK to apply pressure when setting new bevels. But make sure to back way off with the pressure when you get close to apexing, before the burr forms. Let the grit do the work, at a light touch, in that phase.
Click to expand...
Bingo! I am using plated diamond stones.

So glad to have a path forward and someone who agrees with me. I do wonder that diamond is worse because it is so hard. I always considered that the curve of a knife blade gets more pressure on the stone - and that's where I see this problem the most - always good when theory aligns with experience/reality.

It seems to me that once fatigued you can shave off all you want from outside the sharpening triangle (as I did with hundreds of light passes), but there is still fatigued metal within the triangle ready to roll over with enough pressure from a chopping board etc.

Presumably this can be extended to all apices because any metal - no matter how hard - becomes ductile when it is thin enough, and so any apex will have metal right at the very tip which is just going to roll over. The key is obviously making this tip as small as possible.
 
I have another thought. In hand-sharpening there is no way that any mortal human can be that consistent with their angles. I watch these people using 5k, 8k or higher grit stones....I reckon that with a 5k stone if you had your angle absolutely perfect it would probably literally take a year to make any impression on the apex. And so the only way anyone is making any progress on high grit stones is because they are imperfect; they are only honing the edge when they over-angle by accident.

I think this is relevant to our discussion here - using too much pressure leading to difficult burrs. I wonder that if when I sharpen with too much pressure, if I had my angle absolutely perfect and consistent, that this would not have as much negative effect. But on those occasions where I over-angle a little much, much more pressure is placed on the apex leading to potential folding and fatiguing.
 
peanutaxis said:
Bingo! I am using plated diamond stones.

So glad to have a path forward and someone who agrees with me. I do wonder that diamond is worse because it is so hard. I always considered that the curve of a knife blade gets more pressure on the stone - and that's where I see this problem the most - always good when theory aligns with experience/reality.

It seems to me that once fatigued you can shave off all you want from outside the sharpening triangle (as I did with hundreds of light passes), but there is still fatigued metal within the triangle ready to roll over with enough pressure from a chopping board etc.

Presumably this can be extended to all apices because any metal - no matter how hard - becomes ductile when it is thin enough, and so any apex will have metal right at the very tip which is just going to roll over. The key is obviously making this tip as small as possible.
Click to expand...
My take on why plated diamond hones are so unforgiving...
The abrasive layer is very thin over a hard metal (steel, nickel-plated) substrate. The diamond cuts steel like it's butter, effortlessly. And then the apex of the high points of the edge come into contact with that very hard, unyielding substrate under the abrasive. With any significant pressure, the thin apex is bound to roll severely against that substrate. I've always thought of proper use of pressure on a diamond plate as a touch that MUST be feather-light, almost literally, and done with the bevel as nearly flush to the hone as it can be. Keeping it flush and light with a 'skimming' pass over the abrasive is what produces the best results. And getting a feel for that will also benefit sharpening on any other stone as well.

The 2nd point, on hardness affecting ductility...
The issues with ductility will be much more troublesome in steels at lower hardness, such as with mainstream stainless kitchen cutlery at mid-50s HRC or lower. Steels at hardness levels in high-50s or into the 60s HRC are usually easier to deal with, because when the burr gets thin enough, it'll tend to break away earlier, with the steel's hardness trending less ductile and more toward brittle instead. I notice a difference like this when I compare 420HC between two different knife manufacturers, with one treating their blades to HRC 55-57, and the other treating theirs to HRC 57-59. The same steel type, just a couple of hardness points higher, is easier to de-burr as compared to the same steel just 2 points lower in hardness. And other steels, like simple 1095, can either be a pain to de-burr when at mid-50s HRC or lower, but are beautifully simple to de-burr at HRC 60 or a bit higher, because a thin burr at high hardness will break away almost as soon as it forms.
 
Last edited:
Don't European chef knife makers expect their knives to be steeled frequently instead of sharpened? Steeling is just burr alignment, is it not? If so, diamond plates may very well be the worst choice for softer European knife steels.
 
SharpBits said:
Don't European chef knife makers expect their knives to be steeled frequently instead of sharpened? Steeling is just burr alignment, is it not? If so, diamond plates may very well be the worst choice for softer European knife steels.
Click to expand...
Steeling can be about either realignment or sharpening. Good quality grooved steels work like files to cut the blade's steel, with the hardness of the file's cutting teeth at some percentage harder than typical kitchen cutlery. But a smooth steel will essentially just align a rolled edge or a moderately stiff burr. There can still be some abrasion with a quality smooth steel, but the rate of metal removal will still be very, very minimal.

I see some advantage to the not-so-high hardness of mainstream stainless cutlery, which produces burrs that are ductile but also stiff enough to be functionally useful for kitchen use, when aligned straight. The one caveat is, after a limited number of repetitions of re-aligning the edge over time, the steel at the edge will work harden and eventually become brittle and unstable, at which time the edge will need resetting on a stone.
 
Last edited:
Obsessed with Edges said:
My take on why plated diamond hones are so unforgiving...
The abrasive layer is very thin over a hard metal (steel, nickel-plated) substrate. The diamond cuts steel like it's butter, effortlessly. And then the apex of the high points of the edge come into contact with that very hard, unyielding substrate under the abrasive. With any significant pressure, the thin apex is bound to roll severely against that substrate. I've always thought of proper use of pressure on a diamond plate as a touch that MUST be feather-light, almost literally, and done with the bevel as nearly flush to the hone as it can be. Keeping it flush and light with a 'skimming' pass over the abrasive is what produces the best results. And getting a feel for that will also benefit sharpening on any other stone as well.

The 2nd point, on hardness affecting ductility...
The issues with ductility will be much more troublesome in steels at lower hardness, such as with mainstream stainless kitchen cutlery at mid-50s HRC or lower. Steels at hardness levels in high-50s or into the 60s HRC are usually easier to deal with, because when the burr gets thin enough, it'll tend to break away earlier, with the steel's hardness trending less ductile and more toward brittle instead. I notice a difference like this when I compare 420HC between two different knife manufacturers, with one treating their blades to HRC 55-57, and the other treating theirs to HRC 57-59. The same steel type, just a couple of hardness points higher, is easier to de-burr as compared to the same steel just 2 points lower in hardness. And other steels, like simple 1095, can either be a pain to de-burr when at mid-50s HRC or lower, but are beautifully simple to de-burr at HRC 60 or a bit higher, because a thin burr at high hardness will break away almost as soon as it forms.
Click to expand...
Good points in second paragraph. Makes sense.

Don't think I agree with the first. I am using a Sharpal 325/1200 - a continuously encrusted diamond plate. Even on the 325 side the diamond particles are far too close together for the blade to ever touch the substrate. If I am right your argument still works, it's just that the blade is hitting the far harder diamond!
If we are talking a diamond plate with grouped diamonds like an Atoma stone - I would think that to get your blade to hit the substrate your error in angle would have to be so huge that it would never happen. Further, if the blade ever did hit the substrate during a stroke, your concern would not be the apex hitting the substrate but with the far harder raised diamonds rapidly approaching the apex!

I am absolutely going to take your advice and use FEATHER-light strokes on my diamond from now on. I plan to also drag the apex at 90° across a dowel as a proof-test; to drag any fatigued metal off the apex. This way I am testing and getting immediate feedback on my success or otherwise.
 
You must log in or register to reply here.
Back
Top