An Existential Hardness Question

Ack. Deadboxhero ... thank you. I am going to need some time to digest (after slicing veggies for dinner. :). . Will try to to understand and respond sometime tomorrow...
 
Last edited:
If i may ask,how come you differentiate so between chef and butcher knives?

The reason i ask is that i do a Lot of cutting up of fish...In very harsh conditions,every cut through the skin,And against a surface of a board...Moreover,most of the fish are out of a gill-net set in a really silty river,where in addition to everything there's a % of basaltic glacial silt stuck to the outside of skin...
So things being discussed here are of a vital importance to me...I'm having a very tough time keeping my knives sharp(shaving-sharp is plenty,but very difficult to maintain on production SS processing knives such as Dexter or Victorinox).

I make the distinction because of how people use them. Like your example,
the knife is subjected to conditions that dull any knife. It's more appropriate to hone frequently, and use a steel that does so easily enough.
 
I make the distinction because of how people use them. Like your example,
the knife is subjected to conditions that dull any knife. It's more appropriate to hone frequently, and use a steel that does so easily enough.
Then I guess I need to ask why not apply that same thought to any cooks knife that is constantly rubbing up against a wood cutting board, however carefully or gently, as that contact will dull the blade? I am thinking that is exactly my point....
 
Then I guess I need to ask why not apply that same thought to any cooks knife that is constantly rubbing up against a wood cutting board, however carefully or gently, as that contact will dull the blade? I am thinking that is exactly my point....

I totally got/get your point, and for many knives, I think many people would agree that ease of sharpening is more important than maximum edge life. However, it seems the consensus, at least on this forum, is that kitchen knives achieve the best balance of performance with the highest possible hardness that the steel and geometry will support.

I don't think it's crazy that a few people might prefer softer kitchen knives.
 
To me the question becomes, what are you giving up by going harder or softer? The testing Larrin did showed that many of the modern steels are tougher at Rc63-65 than O1 or 1095 at Rc59. I see no reason to leave performance on the table and lose the fine edge stability by running z-wear, V4e, 26c3, or cruforge v below Rc62. He’ll, I can run a-tuff at Rc62, and be tougher than L6 at Rc58. I don’t find any of these steels hard to sharpen. If we were having problems with chipping, of course we should use appropriate harnnesses for the application, or choose a different steel. If you go softer, you cannot support the fine edges.
 
C Cushing H. reading through this it appears that you sharpen knives on a power grinder.
I don't advocate that but I know it's done. ok fine.
So your option of sharpening when you need it is to goto your power grinder. If I understand you correctly, you don't use stones to sharpen.

If I (or you) think about this from your customer's POV, they are pro chefs or enthusiast collectors (i'm talking kitchen cutlery)
They don't have grinders, But they do have stones and know how to use them.
they have no problem touching up an edge with a 6K stone during the middle of some butchering session if required.

So for the end user customer, I find almost NO ONE asking for or desiring a softer steel that is easy to sharpen...
Most of my knives are a laminated steel with a Hitachi white core which is very easy to sharpen and 63-64 RC. I haven't found anything that is easier to sharpen than this steel on a waterstone.,

so while it's interesting to have a philosophical question..., if you are making knives for a living and relying on performance as one part of your success in selling knives, a soft steel has no place. Knowledgeable customers have sharpening skills and stones and can sharpen their high hardness modern steel knives just fine. This is my experience with my customers.

regards
Harbeer
 
Last edited:
I haven't read all the posts, but will offer some comments on hardness history and modern knives.

Picking the final hardness has always been a factor of available HT methods and the desired sharpenability.

Starting around 3000BC and continuing for several thousand years, knives were made of crudely smelted steel, and hardened by eye in some sort fire and in some sort of of home brew quenchant. The blades were sharpened on some sort of natural rock by hand. These blades were probably Rc 40 at the most. People considered that hard.

As time went by, steel was alloyed a bit better, rocks were hewn into grinding wheels and sharpening stones, and HT was a bit more refined. This was the norm from around 500AD to 1900AD. These blades were around Rc 45-50 at most.
People considered that hard.
It started improving during the last half of the 19th century with the advent of the Bessemer steel processes.

By 1900, steel metallurgy and manufacturing was pretty good and HT was much better understood. Alloying was still low and simple. Machinery was used to shape and grind the blades. HT was done to a max of Rc55. This would allow the user to easily sharpen the blade as it got dull. Home sharpening was still by a stone of some sort. During most of the 20th century, knives were between Rc45 and Rc55. People considered that hard.

Around 1990, with knifemaking becoming a popular hobby, and newer steels becoming available, hardness slid up to Rc 58-60 as the norm. Most everyone is very happy with this hardness range. This hardness could be easily shaped and sharpened on belt grinders with SC and AO belts and powered wet grinding wheels, and kept sharp by most users with a good Norton or other sharpening stone. To make sharpening easier, all sorts of sharpening systems and machines came out … with most ending up on shelves and in drawers. It wasn't that the Chef's Choice or Lansky couldn't sharpen a knife well … it was that they were expensive and required some skill. Good as they were, they left a poor edge more often than not and couldn't compare to a sharpening stone for ease.

With the advancements in both metallurgy and equipment of the last 20 years, Rc 63-65 blades are now possible and sharpening them can be done with our modern belts and equipment as well as diamond plates and laps. The issue is that the normal user can't maintain the edge easily. Diamond stones are available for the home user, but most people either don't use them or use them wrong. New sharpening equipment came out, some costing thousands of dollars, but it didn't change the public's desire to quickly and easily sharpen their knives.
The general public still wants a knife that is easily resharpened in the kitchen in a few minutes or less. Commercial knives, both kitchen and hunting/fishing, have barely increased in hardness since 1990. The vast majority still range between Rc55 and Rc58 . Kitchen knives have started to slide up to Rc60 only in the past few years. The trend for hobby knifemakers is to make them really hard and sharpen on their equipment. Rc 62-65 has started showing up often. You even hear about guys using special metal alloys and getting Rc67 knives. This is a good thing for the maker/user, but won't affect the public's oppinion much at all, due to the end user not being able to sharpen the knife properly himself.

The thing to keep in perspective is that an Rc 55 knife will cut just as well as an Rc65 blade. The difference is in two main areas - Edge life, and edge durability. At Rc 65, the edge will not wear down and get dull as fast as the Rc55 edge, but it will chip much easier. The Rc55 edge can be quickly sharpened as often as needed, but the Rc65 edge will have to be sharpened using special equipment and skills. Again, the general public won't want a blade that will chip easily if misued or one that they can't sharpen easily.
 
If I (or you) think about this from your customer's POV, they are pro chefs or enthusiast collectors (i'm talking kitchen cutlery)
They don't have grinders, But they do have stones and know how to use them.
they have no problem touching up an edge with a 6K stone during the middle of some butchering session if required.
Yeah, i do get, and agree with this. As i wrote the first post i was actually thinking that if i was a professional chef, i would likely be touching up a blade before i started a shift. But i am not ... i am just a husband and dad rushing to get food prepped and cooked in an hour or so, at the end of a day where my activities had absolutely nothing to do with knives. My question was NOT intended toget folks here to change their practice ... it was more to note, and try to understand why, even though i love the newer steels, i still feel like there are some disadvantages with them, at least as i find myself using them.

( that said, i DO keep a waterstone on the kitchen counter - drives my wife crazy. I also believe there is a different “feel” (hard to describe) to the stainless steels vs non stainless, which i “think” is more related to alloy than hardness (my Hitachi white and blue blades “feel” more like my softer highcarbon blades, even though they are something like rockwell 62-64. I have a length of CPM 154 that will shortly become santokus, pettys, and steak knives. I will learn more from that.
 
reading through this it appears that you sharpen knives on a power grinder.
I don't advocate that but I know it's done
Harbeer - actually, not really. this might be a different discussion, but it is closely enough related to hardness (and microstructure) that I will add something. What I have done has shifted a lot over the years (depending on technology available and my own financial resources. right now I will use any of a combination of: tormek wet grinder, 2x72 grinder, and two levels of waterstone grit. What I actually use depends on the knife geometry, steel composition and hardness, and condition of the edge. the tormek works great on softer simple steels. however, on harder steels (say, 62 and above) it struggles (the "Japanese waterstone" is worthless on hard steels, despite the ~$400 price tag. The blackstone silicone wheel will cut the harder steels, but (at least with the Hitachi white and blue) will leave something of a chipped edge. This can be cleaned up in literally a minute or two on a waterstone leaving a really really nice edge. I was surprised to discover (after reading several posts here, and speaking with the folks at Pops) that a grinder, run at low speed (I use 10%) using ~400 grit belt actually cuts all the steels I have (including VG10, AEB-L, and the Hitachi white and blue), and does not seem to chip the Hitachi steels (larger carbides.....) - which I was very surprised to discover. Usually, just the edge off the 400 grit on the grinder is more than good enough for my purposes. If I wanted a really, really smooth edge, I could then take it to the waterstones - but dont tend to.

A LOT of my knives are 15 - 25 - 35 years old. After repeated sharpenings, the edge profile has retreated a fair amount - and especially with the european designs with the full height bolster which now protrudes below the edge, that bolster gets badly in the way of using the tormek (which needs a continuously convex edge to maintain contact with the stone). That same edge geometry creates problems trying to use a stone (you have to use the edge of the stone, which damages the stone). On the grinder, however, it is a simple matter to use the edge of the belt a little to get into that heel portion of the edge.

As a general matter, I find the softer steels are more forgiving to sharpen (they dont chip), and almost anything cuts them, and they are cut by the abrasives much faster than the harder steels.
 
I also believe there is a different “feel” (hard to describe) to the stainless steels vs non stainless, which i “think” is more related to alloy than hardness (my Hitachi white and blue blades “feel” more like my softer highcarbon blades

So much of our intuitive impression of cutting comes from the initial moment of the blade contacting the material.Does it have a tendency to "bite in",just how easily/readily does it "bind" to material,begins to Penetrate,before the actual severing begins?

How much is there to that myth of Cr carbides being large,globular sort of structures that have much more of a tendency to "slide" on material vs much finer cementitic/perlitic low-alloy steel edge?
 
So much of our intuitive impression of cutting comes from the initial moment of the blade contacting the material.Does it have a tendency to "bite in",just how easily/readily does it "bind" to material,begins to Penetrate,before the actual severing begins?

How much is there to that myth of Cr carbides being large,globular sort of structures that have much more of a tendency to "slide" on material vs much finer cementitic/perlitic low-alloy steel edge?

larger carbides result in a toothier feel when cutting. AEB-l is the stainless that bucks that trend, due to very carefully selected alloying minimizing large carbides. PM steels minimize this problem.
 
Larger carbides are not necessary a bad thing like folks were saying 10 years ago. They can help make the edge more aggressive with slicing/drawing the edge when sharpened properly.I the matrix is harder +60rc it holds the Carbides better

So much of our intuitive impression of cutting comes from the initial moment of the blade contacting the material.Does it have a tendency to "bite in",just how easily/readily does it "bind" to material,begins to Penetrate,before the actual severing begins?

How much is there to that myth of Cr carbides being large,globular sort of structures that have much more of a tendency to "slide" on material vs much finer cementitic/perlitic low-alloy steel edge?
 
C Cushing H.
I think you need to try a higher quality knife and ceramic honing rod before making sweeping conclusions about hardness making rapid honing difficult.

Do you make knives?
Perhaps you can make one.
 
try a higher quality knife and ceramic honing rod before making sweeping conclusions
DeadboxHero - I am not making sweeping conclusions - I am making an observation and looking for other's perspectives - there is a difference between the two. I thank you for your perspective. (and yes, I agree I need to try a ceramic honing rod for my more modern steel blades. I do not think that changes the basic point/question though.
 
To add to the discussion, when I sell high alloy, high hardness knives, which is an investment for the customer, I suggest they invest in a quality sharpening system like an edge pro.
 
You'll have to try and update the thread.
Also, use a better quality knife too.
Perhaps a custom blade

DeadboxHero - I am not making sweeping conclusions - I am making an observation and looking for other's perspectives - there is a difference between the two. I thank you for your perspective. (and yes, I agree I need to try a ceramic honing rod for my more modern steel blades. I do not think that changes the basic point/question though.
 
Then I guess I need to ask why not apply that same thought to any cooks knife that is constantly rubbing up against a wood cutting board, however carefully or gently, as that contact will dull the blade? I am thinking that is exactly my point....

I tell my kitchen knife customers that for best performance, they invest in an end grain cutting board. I will make one for a reasonable cost for them if needed.
 
when I sell high alloy, high hardness knives, which is an investment for the customer, I suggest they invest in a quality sharpening system like an edge pr
Yeah - that is part of the point. I do worry, for some of the knives I have made and given to family and friends, that maintainability of the edge is something that is going to come back and hit me ... but I will deal with that when the time comes :-)
 
Yeah - that is part of the point. I do worry, for some of the knives I have made and given to family and friends, that maintainability of the edge is something that is going to come back and hit me ... but I will deal with that when the time comes :)

wjen I take an order, which I mostly only do for returning customers, i interview them to get a balance of what they need. One chef has a Rc62 15n20 knife for work, as it is basically unbreakable, and easy to touch up. His Damascus set I’m working on is W2/15n20, Rc64 for home. He’s ordering an edge pro for that. I send a strop, and compound with each kitchen knife. I do free sharpening, but with cross border shipping, most don’t take me up on it. Locals do. Ask the customer how they will maintain the knife, how often they sharpen it, and how they would sharpen it.
 
Back
Top