How to sharpen a chef's knife

[Fred]

It is a rough draft. I ran through it quickly. I intend to improve it. Any comments? Click here. (http://www.foodieforums.com/chefsharpening.htm)

[chefjohn]

great start!!!! great to have access to such knowledge

[Andy777]

Looks good to me Fred. Is there a benefit to testing for the burr with the nail over feeling for it with your thumb feeling along the blade (perpendicular to the legnth) pushing towards the edge? (I couldn't get it to make sense so I drew a picture and attatched it. What skill /ubbthreads/images/graemlins/crazy.gif!)Or is it just another way of doing it?

[Fred]

It's another way of doing it. The advantage of the the burr but the size of it. It gets smaller, obviously, as you progress to finer grits. Also there isn't any danger of cutting anything. Nails are harder to cut than you might think.

[Peter]

Fred, this is a very understandable explanation. But you want commments, here are my 2Ct.

A sketch with sharpening angle depending on steel hardness might be nice.

The owner of Guede showed another steeling method on TV. He held the steel and knife horizontal and wiped the knife away from him (against the edge). So he reduced the problem of using too much pressure on the edge. Personally, I needed quite a while to avoid pressure and I believe, most home cooks do have a steeling problem.

Peter

[icevic]

I would like to see more explanations about the angles. Without a sharpening device, how do you know what angle you are at? How does anyone know what angle their knife is currently at? Do they use protracters? When you say "12 to 15 degrees", how do you know if it is at exactly that angle and not 9 or 18 (for example)? I have never understood how people determined these numbers.

[Fred]

I do it as you describe except I also steel toward me to do the opposite side of the blade. I think the method I describe in the article is good for beginners, though, because it makes it easier for them to find and maintain the angle.

I hesitate to get too much into recommending angles since different manufacturers heat treat steels differently. Also cooks use knives differently. As an example, a boning knife, which rarely contacts a cutting board, can be cut to a very acute angle compared to a chef's knife. Perhaps I can expand on the method for experimenting with the angle to find the one that is best for the knife.

Thanks for the comments.

[Grouch]

For these small angles, the sine of the angle can be approximated by [degrees/60]. So, the sine of 15 degrees is ~15/60=.25. To position a 1.5" wide blade at an angle of 12 degrees, make the spine [1.5*12/60]=.3" off the stone.

[Peter]

[ QUOTE ]
I hesitate to get too much into recommending angles ... Also cooks use knives differently

[/ QUOTE ]

Yes, I remember my chisels had the officially recommended angle (30°) but an Italian colleague preferred >35°. The difference was, he worked mainly outside while I worked more at the shop on old and new furniture. This is similar to what you say about boning knives.

Peter

[Scott]

Andy,

I can tell you, from experience, that the thumbnail method is far superior to feeling for the burr with the thumb pad (though your fingers may be much more sensitive than mine). I used to use that method myself, but now never use it.

The process that Fred uses allows you to even determine degrees of sharpness. You can tell how sharp your knife is by the angle of the blade when it either stops biting or begins shaving your nail (when it is almost parallel to the nail). The closer to parallel (both sides) the knife is when it STOPS biting (and starts "skidding"), the better and sharper it is. The method dramatically improved my feel for how sharp my knives were and how sharp I have been able to get them.

From reading here and at KF, in my developing understanding, there are two schools of thought in sharpening.

One school of thought is that a burr is necessary for cutting and it is the burr that does the cutting. If it is a ragged burr, that is even better because it will cut better... kind of like a serrated knife. This is considered to be especially true for cutting tough-skinned items like tomatoes with a slicing motion.

The other school of thought (the one I am coming around to) is that a polished edge is the best. By polished edge, I mean one that is smoother and has less of a burr, approaching no burr. This is the school that the Japanese appear to be and appears to be the method promoted by Steve Bottorff and John Juranitch (Ch. 3 & 4 here http://users.ameritech.net/knives/knives1c.htm and http://users.ameritech.net/knives/Juranitch1977Feb.htm ).

To me, this makes more sense. A rough burr will be thinner (more likely to fold over) and will not have the same amount of steel surface in contact with the items to be cut, increasing the wear on the edge. With a smoother edge, there will be a much smaller burr (which would be less likely to fold over and if it did, it would still be "sharper") and there will be more surface area contact, increasing the amount of cutting being done.

However, not having a microscope (even a cheap one) that will allow me to compare edges and their cutting efficacy, I cannot say. Logically, the "polish school" approach is more appealing to me. Do I know this for sure? Heck, no! This is just a theory I have developed to help me understand sharpening better... and it has helped ME. However, YMMV! /ubbthreads/images/graemlins/smile.gif

One thing I can say is that I bow to Fred's MUCH greater experience with this and I have learned a tremendous amount from his posts!

Scott

PS. Your drawing skills are better than mine... /ubbthreads/images/graemlins/wink.gif

[**DONOTDELETE**]

Fred,
There's only about 1,000 different ways to skin this cat called "knife sharpening" and I think you did a very good job describing your methods on how to do this. /ubbthreads/images/graemlins/smile.gif

--Dave M.--

[**DONOTDELETE**]

Scott,
You can count me in on the "polished" side of this discussion.

--Dave M.--

[Fred]

Let me address two posts here. Icevic, yes I use a protractor - or at least I did in the beginning. Now I can tell the angle just from experience. The truth is the number of degrees isn't the issue. The issue is acuteness vs. steel hardness and the only real way to get there is through experimentation. It's time consuming in the beginning but pretty easy after some experience.

Scott, sharpness is really a function of the bevel angle. Polishing the bevels simply reduces the friction between the edge and the product being cut. How would logic explain improving the cutting ability of an edge by increasing that friction? That question should clear it up for you.

[RETREVR]

[ QUOTE ]
Fred, this is a very understandable explanation. But you want commments, here are my 2Ct.

A sketch with sharpening angle depending on steel hardness might be nice.

The owner of Guede showed another steeling method on TV. He held the steel and knife horizontal and wiped the knife away from him (against the edge). So he reduced the problem of using too much pressure on the edge. Personally, I needed quite a while to avoid pressure and I believe, most home cooks do have a steeling problem.

Peter

[/ QUOTE ]

I have seen people plant the tip of the steel like fred suggests. It is a good method.
If you choose to hold the steel out in front of you, it is a customaty courtesy to swipe the knife towards yourself. Swiping away from yourself may never be a problem, but in a busy kitchen you reduce the likelyhood of sending someone to the hospital.

[Oded]

I see sharpness as the perfect zero thickness line created at the meeting of two perfectly flat surfaces. The closer to perfection you can get, the sharper your blade is.
What stands between us and a perfect flat surface are scratches and other 'imperfections'. The finer grit you use to polish your edge, the closer you are to that perfection etc.
I also agree that once the edge has penetrated into whatever is being cut, you want as less friction between the blade and the food. The extreme situation will be cutting fish for sashimi where crisp edges and polished surfaces (of the fish this time) are must. This why you will see Yanagibas but Debas being honed at higher grits and polished with jeweller’s rouge, newspaper or whatever is preferred by the user and makes it smoother.

[RETREVR]

[ QUOTE ]


Scott, sharpness is really a function of the bevel angle. Polishing the bevels simply reduces the friction between the edge and the product being cut. How would logic explain improving the cutting ability of an edge by increasing that friction? That question should clear it up for you.

[/ QUOTE ]

I have been in a pissing match with a guy over on egullet about course edges vs polished edges. He has custom cast dendritic (sp) knives that were built around the philosophy of a course edge. He insists that courser is better regardless.

[Fred]

And how does he explain that more friction cuts easier than less friction? I wouldn't be able to explain it.

I've heard the arguments for "micro serrations." Serrations, micro or otherwise, work something like teeth on a saw. That can be handy for, say, breaking through the hard crust of a loaf of bread using a sawing motion. That's why bread knives are almost always serrated.

However, polished serrations will do a nicer job of sawing than coarse ones. If the argument is about edge profile then fine. There are situations where one profile will work better than another. That doesn't have anything to do with coarseness or fineness of the honing work or the abrasives used to do it. Finer or more polished is always better whether it is a saw blade, a serrated bread knife or a gyuto. I think the laws of physics make that obvious.

Incidentally, I hope he isn't using the dendritic 440C stainless that was pioneered by David Boye. I've used that stuff and it is really, really brittle. It would certainly be harder than the average Western kitchen knife but it would be a far cry from VG-10 or S30V or any of the high tech stainless steels with more toughness.

[Scott]

I'll address other things in additional responses...

Fred,

I think that we are talking about two different things here. Probably because I wasn't as clear as I could have been. I should have stated, "Given the same bevel, I now believe that a polished edge will be a sharper and more durable." I had assumed it was understood that we wouldn't compare two different bevel angles, which polished or coarse would not affect.

[ QUOTE ]
How would logic explain improving the cutting ability of an edge by increasing that friction?

[/ QUOTE ]

About the logic of why would a "coarser" edge, I'm not sure I understand the question. Do you mean to say that an edge with increased friction would cut better?

As my disclaimer said, I don't have much experience with this and that my "theory" was one that I had reached primarily through reading the opinions of others and, a little bit, based on my own, limited, experience. I "developed" it to help ME with understanding sharpening. And it has helped me dramatically improve my ability to sharpen my knives. For others, YMMV.

Also, so far as I know, nothing I have said is in conflict with your sharpening article. In fact, I have said numerous times that I thought it was excellent and I have/am learning a tremendous amount from you.

With that said, what I believe, subject to further learning, is that a smoother edge should last longer and cut better over its life between honings... given the same steel and bevel angle. This seems to be borne out by the discussions both here and on KF, the articles I listed, and by the obsession of the Japanese with polishing stones.

I seem to have touched a nerve with you and I'm sorry. I have a tremendous amount of respect for your knowledge, experience, your willingness to share both, and you as a person.

Perhaps it is because I'm working on my PhD (in business). The training we get in how to think (in addition to the amount of reading/learning we have to do) automatically pushes us to try to create theories about what we see and then test them to see how well they hold up and revise them as necessary. This can be quite irritating (ask my wife). /ubbthreads/images/graemlins/crazy.gif

Anyway, sorry for any misunderstandings.

Sincerely,

Scott

[Scott]

Fred,

I guess I'm confused. Is it understood that an edge with higher friction cuts better than one with lower friction? If so, I guess I need some clarification to understand this as, indeed, it does seem counter-intuitive/illogical.

I guess I don't understand how we define "increased friction"? Is this the cutting part of the edge? Is it drag due to two smooth, wet surfaces clinging to each other due to capilary acton/surface tension (actually I guess I'm now talking about how food "sticks" to the blade)? Is it because the sides of the edge are rough? Is it because of the micro-serrations of the edge/burr?

From what I can see, a smoother (polished) edge is sharper, lasts longer, and is easier to cut with. Both Bottorff and Juranitch's writings seem to support this. However, I just don't have the experience to be able to say, with any justification, one way or another. So, I'm back to relying on what others say and "logic". /ubbthreads/images/graemlins/crazy.gif

On one hand, as I read down further, from what I can see, in my earlier post, it seems like we were arguing apples and oranges. I was talking about the "fineness" of both the side of the edge and the lack of width of the edge, not the angle of the bevel.

On the other hand, we seem to be arguing two sides of the same coin? That a polished edge cuts better?

I hope I can eliminate both my lack of clarity and lack of understanding, which seems to be putting us at odds when, perhaps, we are not.

Thanks.

Scott

[**DONOTDELETE**]

RETREVR,
Although I havn't read the discussions your referring to it does seem that this individual is grouping that particular steel type with all others. Maybe he feels that since his knife's edge is coarse, and it kicks ass this way, that this would mean that all knives should have a coarse edge. We know that's not true but he's convinced and that's that.

I offer this basic concept...

Use a wood chisel that's been sharpened on a coarse to med. stone.

It works good, is extremely adequate, and gets the job done...no question.

Now, use a wood chisel that's been lapped to 8000x grit >.

It works great and you can't remove the smile from your face. /ubbthreads/images/graemlins/grin.gif
You can, depending on the work, push cut (no hammer required) the chisel, your actions are more precise (controlled), the results are better, your time (in job) has been reduced, and your less fatiqued as the work is performed with less effort.

Anyone who thinks differently about this may want to check with those woodworkers who spend hours on bench stones, or pay dearly, to get their chisels sharpened to that state.

I don't care what the task/tool is...I always prefer a highly polished edge. The people who argue this, most likely, have never experienced an extremely refined polished edge. If they had, then they wouldn't be arguing, trust me. /ubbthreads/images/graemlins/wink.gif

Keep up the fight!! /ubbthreads/images/graemlins/cool.gif

--Dave M.--

[Peter]

[ QUOTE ]
in a busy kitchen you reduce the likelyhood of sending someone to the hospital

[/ QUOTE ]

/ubbthreads/images/graemlins/laugh.gif
it was a TV report about the process of knife making in the Guede factory, possibly a PR movie. The steeling method was strictly meant for home cooks not to get rid of your colleagues.

Peter

[Peter]

[ QUOTE ]
I don't care what the task/tool is...I always prefer a highly polished edge

[/ QUOTE ]

I second to Dave, a polished edge is recommended for chisels or other blades.

OT, the machines that produce very thin slices for electron microscops have polished blades as well as razor blades.

[Fred]

Scott, you misunderstand. You didn't touch a nerve. I was just trying to answer your question. Sharpness is the bevel angle. We all understand that. Polishing the bevels reduces friction. Those that think a coarse sharpening is better would have to explain a completely illogical concept. If you took a mirror polished edge and then ground it on a coarser stone, that would remove the polish and increase the friction. Logic tells you that added friction can't make the job cutting job easier. It has to make it more difficult. So my point is that a polished edge is always better than a coarse one - all other things being equal.

People often confuse the sharpness of an edge with the finish on the edge. A more acute angle is sharper and cuts better. Whether it cuts better long enough to be useful is a different matter. Polish on the bevels is never a negative. Removing the polish will never improve the performance of an edge. Logical. No?

[Scott]

Fred,

Ah, I understand. I'm glad that my understanding was better than I thought. Thanks for clearing that up!

Scott

[mikemac]

comments - right....is this intended for retail/ home cooks, or as course matter in a school? Starting with "the burr", "spine" and "edge" would be over the head of the average, and maybe enthusit home cook. If it's course material, and it follow the chapter "Anatomy of the Knife"...well ok. I don;'t see any mention of which grits to use and why. Grinding and swiping...is grinding using enough pressure to dent cold butter? Point of referance like "on the average Henkels (used in the home kitchen for 3 months), and a 1000 grit King waterstone, using enough pressure to leave a finger dent in cold butter, you should raise a burr in 4-5 minutes. Swithcing to the 6000 grit stone, use your fingers to guide the blade over the stone, using only the weight of the blade as preassure..."
How often do you add oil / water to the surface of the stone? and....for now, my personal source of frustration...how do you maintain your angle, how do you adjust your grip, for the last 1/3rd of the blade as the edge curves up to the spine near the tip?

[Fred]

Good comments. Yes, the purpose was home cooks with little or knowledge of sharpening. I did discuss grits simply by recommending a medium and fine. I don't want to get more complicated than that for this piece. I should make some comments about pressure and the issue of sharpening the tip is a good one. It may be a little challenging to describe it but I'll give it a shot. Good cooking.

[Scott]

Fred,

I just thought of something (yeah, I do think occasionally... /ubbthreads/images/graemlins/smile.gif). From what I've read, the definition of "coarse", "medium", and "fine" (not to mention, "extra fine", "super fine", etc.) changes depending on what web site you read and whether you are referring to a waterstone, diamond stone, or oilstone. Perhaps at least putting grits in parentheses would help clarify that for the readers.

I know it drove me nuts when I was first learning!

Scott

[mikemac]

I'll second that...when I bought my DMT "duo stone", they were quoted in microns (still are), and I thought that their "extra fine" was similiar to or finer than my king 1000x6000. Now I think I've seen something that shows the extra fine as being close to a 1200