# How Often Do Chefs Sharpen



## souplvr (Feb 5, 2012)

Hello Chefs,

I wondered if you could give me some insight into sharpening. Couple questions I've wondered about for some time:

*How often do chefs sharpen their knives?*

The answer, obviously, is when they're dull. And that will depend on frequency of use, technique, cutting boards, the knive, etc. But we were told (where we get them sharpened) that it should be required about once every 3 years (we have Globals/Shuns). Now, I use them every day to cook dinner and even I notice a difference 1 year after sharpening. How in the world would a chef cooking 12 hours a day go that long?

*Do chefs use a separate/cheap knife for mincing?*

Not sure about this, but I would think that mincing dulls a knife faster than anything else. I've noticed that the time between sharpenings has drastically increased after a) purchasing an expensive cutting board and b) using cheap mincing knifes in place of the more expensive ones.

*What is the point of a honing rod?*

We were encouraged, last time we had our knives sharpened, to buy a ceramic honing rod. We use it religiously and have noticed it makes quite a difference in maintaining the edge. But from what I understand, it does little actual sharpening--just lines up the molecules. If that's true, is there really any advantage/need to use one at all? Some say that ceramic is a major no no when it comes to japanese steel, which is why I ask.

Any info you can provide is much appreciated.

Thanks!


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## phaedrus (Dec 23, 2004)

All my knives are Japanese, and as you expect, I sharpen when they need it.  A ceramic hone is good if it's very fine.  I use a glass one.  I think only Hand American sells them.  When the glass rod won't bring it back I go to a fine Idahone ceramic.  When that won't bring it back to shaving hair I return to the stones.

I take 10 knives to work every day.  I try to rotate them to distribute wear among them.  I will sharpen a couple and replace them in the rotation with my "bench" of knives.

Probably not helpful, and I apologize.  I have too many knives and am a sharpening geek.


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## boar_d_laze (Feb 13, 2008)

Been a looooooooooooong time since cooking professionally so I hope you'll pardon the lack of credentials. My answers are based more on what I know about sharpening in general and what I hear from my pro friends, than my own long ago experience. That too, though.

First, I agree with every word Phaedrus wrote.

]*How often do chefs sharpen their knives?*

Your sharpener supposes you'll be using a steel of some sort for tune-ups between sharpenings. That said, it's still horrible advice. If you actually got your knives anywhere near as close to being as sharp as they can and should be -- assuming a normal work load -- you'd notice significant degradation after about 3 months.

I know pros who use knives with much better edge holding and edge taking qualities than yours who sharpen their go-to knives after every shift.

A lot depends on what you do, how and with what you do it, but sharpening every other shift is a lot, but not a heck of a lot, for someone who's extremely demanding; while every ten shifts is very long for someone to whom edge quality matters at all.

Either learn to sharpen yourself or find a new sharpener. Your guy is clueless.

*Do chefs use a separate/cheap knife for mincing?*

If by "mincing," you mean chopping on a board, most good cooks use their very best knives for the process. If you mean a particular kind of chopping involving holding the point down with one hand and rocking and rotating the knife through a pile of food -- the answer is probably the same.

*What is the point of a honing rod?*

Whoever told you the about the molecules is not just wrong, but ignorant. Funny though.

Knife edges are very thin and get bent out of true when they're used. That's especially true for those which get a lot of banging on the board; i.e., the knives used for chopping (which you called "mincing"). The softer the knife alloy, the easier it is for the edge to deform, and -- everything else being equal -- the more often it will need truing. Using a honing rod properly bends the edge back to "true."

However there's only so many times you can true a knife before the thin metal at the edge fatigues and the knife will need ever more frequent truing because fatigued metal bends more easily than fresh. After being bent back and forth in order to straighten it, the "bending burr" will break off in pieces; leaving a fresh but unrefined edge. Ideally you'll sharpen before then, but you should certainly shouldn't wait to sharpen after that happens.

The best practice for any cook is to always keep a fresh, fine edge. A steel is your friend for awhile, then not so much.

Good ceramic hones can be extremely cost effective compared to metal or glass. However, any of those materials are suitable for most knives. What isn't suitable are "coarse" and "medium" rods. "Diamond" rods are especially destructive. You should restrict your steeling to fine, ultra-fine and smooth (aka "polished") rods.

It's a common misconception that Japanese knives should not be steeled. It's true that if the alloy is too hard, too chip-prone, or the edge geometry is too thin or too asymmetric, steeling could be counter-productive. It's more likely that a Japanese knife will fit into one or more of those categories than one made somewhere else; but the vast majority of Japanese knives used by American cooks do not. And just to be clear, your Shuns and Globals certainly can and should be steeled as part of your regular maintenance.

Most people don't use a hone properly. The sort of normal, vigorous and repetitive steeling you see on cooking shows does more harm than good. Two to four quick, gentle, and full length strokes on each side, alternating sides after each stroke, is enough to do all the good you can do. Do more and you create unnecessary fatigue.

Hope this helps,
BDL


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## phatch (Mar 29, 2002)

A lot of dullness associated with kitchen knives comes from edge rolling and other deformations rather than wearing away the steel edge itself.  Grit in the vegetables, hitting a bone or seed and so on.

On the common grade of kitchen knives, like Forschner, Henkels, Wusthof, Dexter Russell and so on, they are a hardened to about 55-57 RC.  The Japanese steels and other high end blades tend to run in the 60-61 range. While not a huge jump in hardness, you'll get notably more deformation dulling in the softer steels. This is perceived by the user as poor edge holding/durability.  In the soft steels especially, steeling helps a lot in re-aligning the edge. And its easy to restore in those softer steels as well.  The same concepts apply to the harder steels, but will hold that edge longer generally and require a harder hone/steel and a little better technique to restore.

Once you've deformed the edge and restored it, that bit of steel is weakened and will deform or chip more readily in the future. So you'll find that the knife needs more steeling more often until you just need to remove that weakened metal totally by sharpening in a new edge on the stones.

The original concept behind a steel was that it was harder than the knife blade itself and thus would work to re-align the edge. As fewer and fewer people knew how to sharpen or steel, the idea of sharpening was merged with steeling and diamond hones and such became popular. These are a bad idea still. Note that Phaedrus uses a glass hone, though not really a hone in the sense of sharpening. Glass is very hard. But very brittle and very fine grained making a good material for the purposes of steeling quite hard steels.

Natural sharpening stones are softer than the steels they sharpen. If you use synthetics, those are usually harder than the steel, a synthetic sapphire or diamond relative.


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## boar_d_laze (Feb 13, 2008)

Phatch,

Your hardness numbers are close, but wrong. Most current higher end German knives claim hardness at 57-58RCH; Wusthof claims 58 for instance, and Forschner 57-58. That's not way below the more Japanese common knives -- Globals claim 58, as does MAC for its "lesser" knife series, to name two very common examples.

On top of that hardness is very difficult to measure meaningfully, and most manufacturers claimed numbers are -- shall we say -- optimistic. If anyone can tell the difference in use between a Global and a Forschner, he's probably fooling himself. Shuns tend to run a little harder -- around 60RCH -- and that is a difference you can feel, relative to say a Wusthof, but Shuns have other issues.

Lastly, "C" hardness is more of a metaphor for what matters with a knife than of actual importance. "C" hardness measures resistance to indentation. "Scratch hardness," and "impact hardness" are of more direct importance.

The thinking behind harder hones does include they're being more appropriate for harder alloys, but mass and angle are far more important. While there are limits, they aren't often encountered in the real world, and you don't need the rod to be harder than the knife for it to accomplish its work efficiently. The big benefit to ceramic and glass hones are their relatively fine surfaces, resistance to scratching, chipping and other wear, and the ease of keeping them clean.

One of my rods is a well-worn Henckels from the seventies. I believe the nominal hardness was 59RCH. It started on the coarse side of fine, and has mellowed to "ultra fine." I have no trouble using it on any suitable knife, no matter how hard it is.

The Hand American Borosilicate hones are great, but work best in a system and aren't a good choice as an only rod. I've been using one for many years, and reviewed it here (gone with the format change). The review is on my blog, along with a tutorial on steeling.

_ Natural sharpening stones are softer than the steels they sharpen. If you use synthetics, those are usually harder than the steel, a synthetic sapphire or diamond relative._

It's hard to figure what you're trying to say. The actual abrasives in sharpening stones -- whether naturals or synthetics -- are always harder than the knives they sharpen, otherwise they wouldn't sharpen. I think you may be confusing the abrasives with the binders. If so, natural binders can be quite hard -- harder than any synthetic. The most common abrasives in synthetic stones are silicon carbide and aluminum oxide. At a guess AlO is more common, but it's not related to gems. There are a variety of abrasives in natural stones, some closely related to gems and some less so. If this isn't responsive to what you meant, my apologies.

BDL


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## phatch (Mar 29, 2002)

Sapphires are Al2O3. Same construction as Corundum and all the aluminum oxides/alumina of that designation used as abrasives and lots of other things.

Yes, the abrasives in natural stones are harder than the steels, but the stone as a whole is softer, thus the dishing and other wear.

Most of the synthetics are alumina throughout, at least in my experience.


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## boar_d_laze (Feb 13, 2008)

My bad, I should have said that there weren't many silicon carbide gems and said aluminum oxide instead. Al2O3 is rubies as well as sapphire. Apologies for the confusion.

Wear depends on the binder. Typical clay binder synthetics will dish more quickly than just about any natch, other than soft sandstone binders. For instance, how long will it take to dish a Suehiro Rika relative to a translucent Arkansas? I can't think of any synthetic stone offhand which will dish slower than a black or translucent Arkansas, or one of those Chinese ultrafines for that matter. It just depends.

In fact, synthetic water stones are intentionally made to be very soft so the binder comes up and reveals a constant supply of friable abrasive; then as the "mud" breaks down, the stone's grit becomes effectively (as opposed to nominally or actually) finer.

BDL


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## phatch (Mar 29, 2002)

I've never used a water stone, natural or synthetic.


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## souplvr (Feb 5, 2012)

Wow--thanks for the all the info.  Much appreciated!


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## jimbo68 (Feb 3, 2012)

boar_d_laze said:


> One of my rods is a well-worn Henckels from the seventies. I believe the nominal hardness was 59RCH. It started on the coarse side of fine, and has mellowed to "ultra fine." I have no trouble using it on any suitable knife, no matter how hard it is.
> 
> BDL


You bring up a question that I have had for a while. Was going to start a new thread, but maybe here is appropriate.

I buy old Dick steels when I can find them at a very low price. These steels were slick when new, and a few years in a packing house has made them smoother. The weak point is the handle, but I rehandle them with scraps of exotic woods, then either sell them for what I have in them or give them away,

How do these old steels compare to new steels or the glass or ceramic rods? I have several VG 10 Damascus blades, supposedly hardened to 60+ (Kanetsune), and the remnants of my packing house days, 50 year old Forschners. Would I be better off with newer steels?


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## boar_d_laze (Feb 13, 2008)

That's a really, really good question. At a guess, the answer is "probably not unless the rods are nicked." 

A lot of people who know a lot about steeling think it's important to have a rod which is significantly harder than the knives it's truing; but, as someone who likes to think he knows something about the subject, I don't agree. As I understand the process as long as the sharpener isn't too aggressive, given the small size of the contact patch between rod and knife, the rod's got enough mass to true the knife even if the knife is nominally harder. Less true with oval rods though. 

Anyway, instead of the usual, "it depends," I'm going to the other fallback of, "whatever works." 

BDL

PS. Dicks are really, really good rods. My birthday's in late September.


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## jimbo68 (Feb 3, 2012)

Thanks.  The ones I prefer to buy are the smooth round ones with the black painted handles.  I would pass on any that had any nicks or rough spots, and any that were not originally smooth.  The small ones will fit in a counter knife block.  Originally in the packing house they were hung from the knife belt. There is also a larger style that I believe were originally stored on a nail in the side of a butchers block. and will not fit in the standard counter knife block.


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