Is there such a thing - knife that was sharpened too much ?

D

Dantabak

Joined
Oct 11, 2021
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15
Hi,

In the pictures below you can see the same knife. (This is a cheap stainless steel "santoku")
One was used for over a year and sharpened on whet stones and the other is almost new.
You can see that on the old knife the edge is almost touching the divots.
I am just wondering how much can I continue sharpening this knife.
1. Is there a point where the heat treatment becomes bad ? Or another reason to retire the knife ?
2. What about knifes that have one steel in the center which forms the cutting edge and another steel laminated to the sides ?
Can I sharpen past the "cladding line" ?

oECxIq.jpg


oEC3Ep.jpg

Thanks,
Dan
 
Chances are that the tempering runs well into the "divot" area, so your heat treatment is most likely ok for several more mm's up towards the spine, assuming it had a differential heat treatment. I don't see any indication of a tempering/hamon line however, so I suspect that the blade is full-hardened, edge to spine.

The real issue is that as you sharpen higher up towards the spine, the edge becomes more and more obtuse as the blade becomes thicker the more you grind away. You will lose a lot of slicing capability unless you re-profile the secondary cutting edge to a thinner (more acute) bevel to account for this.

Obviously if you sharpen into the divot area, you will end up with a "serrated" kind of edge, and the grind will not be even/flat. This may or may not impact performance, depending upon what you are cutting.

With regards to your point # 2, I suspect you are referring to a San Mai type of steel, where the harder steel is in the middle and forms the cutting edge, while the outer layers on either side are milder steel. The harder steel core should be all the way through the blade from edge to spine, so that should not be of any concern as your cutting edge will always have exposed full-hardened steel.

If none of this makes sense to you, let me know and I will try to clarify further.
 
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Yes, it's possible to oversharpen a blade.

I own a number of carbon steel knives that I inherited from my father (a sous chef) who sharpened some of them so often that he "reprofiled" the blades by wearing away a substantial amount of steel and, in the case of one pocket knife, down to a nub.

Except for the pocket knife (which I keep as a momento), all of the knives are still useful and do not require "retirement."

As for your santoku, I suppose it's possible to sharpen it so much that you begin to expose the ends of the indentations (which were designed to promote release of food that sticks to the blade), in which case you'd create a pseudo-serrated blade.

While "wierd" looking" if the knife still cuts cleanly, there's still would be no need to retire it unless you just can't stand looking at it.

BTW, I also have a cheap santoku like yours, a Henckles, that I never use it. So, I've never needed to sharpen it. LOL! ;)
 
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Your santoku suffers from a way-too-soft heat treat AND those grantons. Go harder, thinner and properly ground....you'll never look back.
-Mark
 
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shane45-1911 - it was very clear.
Not to use a knife is clearly the best way to maintain its edge 😂
Thanks for your answers !!
 
I apologize for interrupting the discussion here, but I just wanted to address the main question:

NO, there is no such thing as a knife that was sharpened too much. See photo.
 

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shane45-1911 said:
There is no way you would know this just by looking at a knife.

Just because it is well-worn, could also mean it was well-used and re-sharpened dozens of times.
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Sure I can. The second pic he posted clearly shows the knife was tempered back to 55 RC plus or minus TWO points. If that is indeed true, then his blade is at a disadvantage from its creation. 57 in a kitchen is right at the edge of acceptable, and still will need to be sharpened or honed fairly frequently, but if it's down around 53.....well, that's just fighting an unwinnable war.
-Mark
 
polish avenger said:
Sure I can. The second pic he posted clearly shows the knife was tempered back to 55 RC plus or minus TWO points. If that is indeed true, then his blade is at a disadvantage from its creation. 57 in a kitchen is right at the edge of acceptable, and still will need to be sharpened or honed fairly frequently, but if it's down around 53.....well, that's just fighting an unwinnable war.
-Mark
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What do you see in the picture that reveals the hardness of the blade?
 
I wouldn't say that any of the knives above have been sharpened too much. They've been sharpened as often as necessary to keep an edge on them.
Knives are supposed to get smaller.
 
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