Hard v Soft

[Marion David Poff]

So Kitchen Knives are generally left soft, making it easy to resharpen them.

Sport Knives are generally made hard, to hold an edge.

What do you think of that?

Why can't a kitchen knife be hard and hold it's edge? I understand the Spyderco ones do.

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Marion David Poff aka Eye mdpoff@hotmail.com
Coeur D'Alene, ID
http://www.geocities.com/mdpoff

An interesting business oppurtunity... http://www.geocities.com/selouss

"We will either find a way, or make one." Hannibal, 210 B.C.

 

[Arizona]

Good question. I guess the only thing I can come up with is, that if the kitchen knives were hard and holding an edge, then by the time they do go dull it would take the chef a while to resharpen them, time that he may not have. I'm thinking of restaurant chefs now, not you in your kitchen. For home use, I guess there is nothing wrong with a hard kitchen knife.
It's a weak try at an answer, but the best one I have

Ingmar

 

[Chefget]

When cutting food products on a good cutting board (the "rubber" type, not the hard plastic), the terms hard and soft are relative.

When using a good O-1 steel knife (kinda "soft"), I can go a week without sharpening the knife; as long as the micro-edge is not allowed to deform due to not steeling. If a sharp knife is given 2-3 strokes (more is NOT better) everytime the knife cuts less than a lazer, the edge will stay a long time.Since the knife is cutting through *much* softer product (meat, vegies, etc) there is no reason for the knife to dull. Only when the knife is used with the micro-teeth not aligned will the edge suffer.

On the other hand, a hard steel knife is like driving a truck...the control is just not there! Its you and the sharpening stone against the knife. Add to this the fact that I can get an O-1 knife much sharper than a German-type blade (but thats just me

), there's very little choice in our kitchen!

As Doc Gundersen would say (regarding stainless against non-stainless steel):

"Any metal that's 5% chrome is only 95% steel" and "The things people'll put up with just so they don't have to wipe off their knives!"

JMHO

-Michael

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Chefget's Knife Page

 

[Jeff Clark]

There is an awful lot more work getting done in a meat packing plant, a butcher shop, or even an active home kitchen than in the field. Why would these more professional workers be less interested in having hard blades than hunters, campers, and "tacticians". I think that much of the current focus on really hard steels is just machismo. Mine is harder than yours kind of stuff.

When you're using up a lot of your time and energy using a knife professionally you want it very sharp all the time. When you maintain it you don't want to spend a lot of time. You also don't want to waste a lot of money on your knives through paying too much when you buy them or too much through rapid wear out. The standard for how to do all this was established a century ago. You get a reasonably high carbon knife, sharpen it on a bench stone then steel it periodically with a smooth steel. Steeling extends the effective sharp period for a knife to last all day through nearly constant use. The simple carbon steel is easy to sharpen once a day. If you want the knife a little sharper you add a pinch of vanadium to the mix and get something like O1 which does the same only better.

The super steels don't fit into this mode of operation. They may last an entire day before they need to be sharpened, but the last hour of that day you may have to work 15% harder than you would with a well steeled knife (a really hard steel is so much more difficult to steel that they are often considered unsteelable). Then when you rehone the blade it might take you 10x as long as the old carbon steel. The ratios aren't as extreme when you compare stainless steels since they are all a little harder to sharpen and harder to steel. The professional blades from Forschners and Russell Harrington are soft enough to steel while the prestige kichen knives tend to be a little harder.

When I'm skinning an elk it is a lot less convenient to stop and steel or hone a knife. It is a hastle carry extra sharpening gear and it is messy to sharpen stuff when you're fighting blood and dirt in the field. My standard for an elk knife is that I want to get all the way through a single elk (hide and all) without stopping to maintain my edge. At the end I want the blade to be nearly sharp enough to shave with. For most of the job I want it to be sharp enough to shave with. This pushes you towards the better alloys. When I only hunted deer I didn't need as tough an edge. Now I look to alloys like A2, D2, M2, L6 or BG-42. In the kitchen I prefer 1095, O1, AUS-8, or MBS-26; however a well designed knife out of a softer mystery steel works very well most of the time. What I really don't want in the kitchen is 440A, 440B, 440C, or ATS34.

As a last note, you have a minimum of material in a kitchen knife and a maximum of fabrication expense. A kitchen knife works best when it is really flimsy. The thinner the better. Most of the cost of the blade is in fabrication so the expense goes up tremendously if you use a harder material for the blade. You don't get as much of your value back out since the thin blades still wear out faster than a hunting knife blade.

[This message has been edited by Jeff Clark (edited 20 December 1999).]

 

[Jake Evans]

Has anyone heard how dendritics do as kitchen knives? I'd like to know about that.

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Jake Evans

 

[Cougar Allen]

It's a nuisance to stop in the middle of a job to sharpen your knife -- unless you're in your kitchen with your steel right there handy. You can take the same approach to field-dressing deer but you'll have to carry a steel or sharpening stone around with you. Some hunters do that....

Edge-holding is overrated. A hunting knife that can field-dress a deer without needing sharpening halfway through is significantly better than one that can't, but is a knife that could field-dress two deer without sharpening significantly better? It would be if you want to field-dress two deer in a row....

The longer a knife can hold its edge the better, certainly, but what are you willing to give up to go longer between sharpenings? Are you willing to give up strength, pay more money, give up corrosion resistance?

If you use a hard kitchen knife you'll spend less time sharpening but it'll be more of an interruption when you do need to sharpen; it won't be just a couple of swipes on a steel; you'll have to really interrupt what you're doing. You're likely to find that annoying ... you're likely to put it off and go on working with a dull knife because you don't want to interrupt your work to sharpen it....



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-Cougar Allen :{)
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This post is not merely the author's opinions; it is the trrrrrruth. This post is intended to cause dissension and unrest and upset people, and ultimately drive them mad. Please do not misinterpret my intentions in posting this.

 

[Crayola]

Working in a meat plant this summer taught me alot about knives. Steeling just became something I did while waiting for my turn at the meat. Like Cougar Allen said, stopping to sharpen when working is a real nuisance. I think that having a "softer" kitchen knife is great, especially if you just get used to steeling. It only takes a couple of seconds (literally!!) so it shouldn't be that bad. Also, how hard is it to set up a SharpMaker? About 15 seconds if you take your time. The hard/soft issue is really about sharpening (I think anyways) which really is overrated. My dad taught me how to clean VCR's: a job that people around here charge $20 for. It takes three minutes and one cotton swab dipped in alcohol. I couldn't believe that people would pay to have this done! The same goes for sharpening!!! How much room in a hunter's pack does a SharpMaker take up? A couple of strokes on the stones in the field ought to tough up a blade. The same goes for the kitchen. Now that I know how to sharpen a blade, I don't know why people have dull blades in their kitchens. Sharpening is just scraping a metal stick on a rock for Pete's sake!
I know that there is much fuss on the forums and elsewhere about how to get a blade so sharp you can skin a fly, but that is just because we are picky and want the ULTIMATE edge. Anyone can get a working edge on a knife, hard or soft.

Sorry for typing so much, I just finished an exam so I am letting it all out! But I still stand by what I said- this hard/soft issue is just for us picky people studying blades and doesn't amount to much when think about it.


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"Come What May..."

 

[Cliff Stamp]

My current kitchen knives are a Phil Wilson fillet knife and light utility hunter. The only thing I don't do with them is cut through bones (Battle Mistress). They are both very hard, the fillet blade (420V) is 59 and the utility hunter (10V) is 62.5 RC. They will respond to steeling but generally I prefer a ceramic rod. The high hardness gives them very high strength and thus the edges are very thin (.01" behind the bevel) and the bevel angles are very acute, less than 15 degrees. Anyone who has used them has always commented later than Henckles etc. blades cut very poorly in comparison.

However, that being said there are several disadvantes to those knives. I don't generally let just anyone use them because the impact toughness is very low. It would be very easy to knock a chip out the depth of the bevel. They corrosion resistance is also not particularly high on the 10V blade. This is one of the reason I keep two Henckles blades in my kitchen. They are very soft and thus almost impossible to chip. They will indent rather easily but they are also just as easy to restore.

One of the biggest problems with comparing different materials, soft vs hard being one example is that in order to make the optimal judgement the blades must be ground so as to best suit the properties of the blade. I have seen many blades that would turn people away from hard, wear resistant alloys because the edges were too thick or on a blade style that needed a different set of properties.

It is also important to know that professionals don't always have the same needs as us regular folks. As an example, a couple of the above posts have commented on smooth steeling a blade constantly during work. While I do this as well on high use low impact blades, I don't do it as much on kitchen knives. Why? Well because steeling is a temp. effect. If you steel a blade nice and sharp and check it later with no use the edge will have returned to its pre-steeled state (the metal will have relaxed to its nonstrained condition). If you are using the blade constantly you will never notice this. However if you only cook a few times a day you will notice that your blades are always less than optimal when you pick them up.

-Cliff


[This message has been edited by Cliff Stamp (edited 21 December 1999).]

 

[Jeff Clark]

Well, that's a new one on me. I've never heard that steeling was a temporary effect. My gut reaction is that it should be no more temporary than other sharpening methods. I'll have to try some experiments.



[This message has been edited by Jeff Clark (edited 21 December 1999).]

 

[Crayola]

Hey Cliff, where did you hear about steeling being a temporary effect? If steel does really do this, that is pretty fascenating

If it is the case then, I recommend steeling before you cook!

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"Come What May..."

 

[Cliff Stamp]

Jeff :

My gut reaction is that it should be no more temporary than other sharpening methods.

Honing actually removes metal, steeling just moves it around (unless you are using a round file - butchers steel) and the edge tends to return to a more relaxed state over time. I keep meaning to do a controlled study and see how the relaxation time is effected by the steel grade .

Crayola, I noticed it myself. As an example if you look towards the bottom of my review (in progress) of the Battle Mistress there is a short paragraph on this in the sharpening section.

-Cliff

 

[Cougar Allen]

That works both ways; if you set the knife aside for a while instead of steeling it the edge will partially realign itself. It used to be a common practice to have several razors and use them in turns to give the edge time to "heal."

It's not the same mechanism as ordinary flexing, I think. Crystals have a tendency to form with the atoms aligned very uniformly in rows ... when that arrangement is disturbed it returns to that lowest energy state slowly, over a period of days or even longer.

Heat helps it happen faster. Welders are familiar with the phenomenon; when you beat something into shape it forms stresses and strains in the steel and then when you heat it up it returns toward the shape it was in before you started hammering and bending it -- not all the way, just a little, but that's often enough to be maddening when you're trying to do precise work.



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-Cougar Allen :{)
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This post is not merely the author's opinions; it is the trrrrrruth. This post is intended to cause dissension and unrest and upset people, and ultimately drive them mad. Please do not misinterpret my intentions in posting this.

 

[Crayola]

Steel that "heals"... don't let the cheapo knife companies find this out! What a marketing scam that could be!!

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"Come What May..."

 

[Cliff Stamp]

Cougar you bring up an interesting point. As I had been doing some work lately seeing how long it took for the edge to degrade I remembered reading about straight razors restoring themselves if left alone in the Straight Razor FAQ. I this process is identical to the steeling unalignment that happens. When you use a straight razor the metal distorts under low stress, this is very similar to steeling (force wise) just going in the wrong direction.

This however brings up the obvious question - how comes knives don't in general "heal" like this. I think it has to do with the level of force the edge sees. Most knife blunting is caused by much greater stress, wood chopping for example. I have never noticed a knife blunted after chopping restoring after I left it alone. If I were to make a guess I would say that it has to do with the extent the steel is moved beyond the plastic deformation barrier.

This is rather interesting, I think I'll check with some people who have worked with thin metals and do some reading. By the way Jeff, I would be interested in hearing about anything you come up with.

-Cliff

 

[Cougar Allen]

It's a small effect and it depends on what kind of steel it is -- the old Gilette Blue Blades lasted a lot longer if you rotated several blades but the effect is so small with modern high-alloy razor blades it isn't worth bothering with even for a tightwad. I'm not sure if that's because the high-alloy blades wear by microchipping instead of distortion or if they distort but don't heal.

Shaving once doesn't disturb an edge much. Even so it doesn't return all the way to its original shape; even if you get a razor for every day of the week and give each blade seven days to recover between shaves they won't last forever.

If you took one chop at a piece of wood and then put the knife aside for several days before taking another chop I think you would get a lot more chops out of a 1095 knife before it got dull. Not very practical, I'm afraid....

If you bend a piece of steel to a perfect right angle and then heat it up to weld it it'll return just a tiny bit toward its original straightness ... maybe one degree? It can be an annoying effect when you're trying to do precise work, but it won't straighten itself out all the way, just a tiny bit. There are some thermoplastics that do return all the way to their original shape when heated, though. Maybe someday we'll have knives made of some yet undiscovered material that never has to be ground to resharpen it -- just heat it up....

Or even better, a blade that'll return to shape without heating and do it fast enough so it never gets dull enough so you'd notice it.



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-Cougar Allen :{)
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This post is not merely the author's opinions; it is the trrrrrruth. This post is intended to cause dissension and unrest and upset people, and ultimately drive them mad. Please do not misinterpret my intentions in posting this.

 

[Cliff Stamp]

Cougar, the chopping example is kind of interesting. I think if I get some free time I will see if I can see a difference. Maybe do ten sets of 100 chops with a day in between and compare to a direct set of 1000 or similar.

-Cliff

 

[Paracelsus]

Very interesting discussion gentlemen! I am not sure I have much to offer, but as a woodcarver, I find that using a leather strop imbedded with microfine metal polish very frequently (every 15 minutes or so) will maintain a Very sharp carbon tool steel edge almost indefinitely during Hard use. Usually the only time I have to stone an edge (on a 6000 to 8000 grit waterstone or ultrafine ceramic), is when I have Not used the knife or gouge for some time (several days or weeks). I think this loss of sharpness happens mostly because of oxidation of the microfine edge. Certainly, keeping an edge (micro-saw) properly aligned during use is the key to a long-lived edge. Ultra-hard materials may support longer edge life, but are harder to resharpen, and don't cut Any better.

Paracelsus
(BTW Cougar, I thought Remulak was a Wacky planet somewhere in Cone Head Space. Is your head pointy too? I already know it's Very sharp)