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Equipment & Gear: Knife Parts
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Cooking For Engineers



Joined: 10 May 2005
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PostPosted: Mon Nov 07, 2005 9:46 am    Post subject: Equipment & Gear: Knife Parts Reply with quote


Article Digest:
Understanding the parts of a knife is important to selecting a knife. Most knifes have the same essential parts and are simply shaped differently for best use in certain applications. Examining the parts of a chef's knife will provide a fairly comprehensive look at how these parts are used and what to look for when selecting a knife.

[IMG]The parts of a knife can be divided into two major parts: the blade and the handle. Each of the common component parts of the blade and the handle are described below.

The blade of a knife is constructed by either forging or cut from stamped steel.
Forged knives are made by heating a bar of steel until softened and dropping the steel into a mold. The steel is then hammered into the correct shape and excess steel is trimmed. The forged blade is then tempered by a sequence of heating and cooling of the steel in order to improve its durability and hardness. The blade is finally sharpened, fitted with a handle, and finished (which may involved polishing to remove any unwanted edges or burrs).
Stamped knives have their blades cut from large flattened sheets of steel. The steel may then be ground down to provide a taper from the spine to the edge as well has from the heel to the tip. Finally, the edge is sharpened, and the blade fitted with a handle. Both forged and stamped blades are made with a protrusion called the tang. The tang is where the handle will be attached through riveting, bonding, or another means.

In the past, forged steel was always deemed to be stronger and more durable than the steel used in stamped knives, but this is no longer necessarily true. The quality of steel used in some stamped knives can exceed the quality of steel in many forged knives. Also, stamped blades can be affixed with parts that are normally only present on forged knives such as a bolster or finger guard. As such, these features can no longer be used to determine accurately if a knife is forged or stamped -- but because a stamped blade is not necessarily a knife of poorer quality, one should not use the fact that a knife is stamped or not to determine if the knife is of higher or lower quality. Instead, the performance of the knife, how well balanced it is, feel, and finish should be much more important to the selection of the knife than whether or not the metal is stamped or forged.

Point - The point is the part of the knife at where the edge and the spine meet. The point is generally used for piercing.

Tip - The tip of the knife is usually considered the first third of the cutting edge including the point. This region is usually used for fine work or delicate cuts. The tip is also used as an anchor during mincing.

Edge - The cutting edge of the blade extends from the point to the heel. Virtually all cutting actions of the knife will use this region. Most cutting motions are performed by utilizing a slicing motion (drawing the knife horizontally while pressure is applied downward through force or gravity). In general, the main type of edges are taper ground edge (where the edge is formed by two straight bevels), hollow ground edge (where convex curves are carved out of the edge to form a sharper, thinner, more delicate edge), serrated edge (where the edge is shaped in a series of teeth), scalloped edge (where the edge is shaped in a series of small sharp arcs or bumps), or single edge (where only one side of the knife is beveled - like a chisel's edge). Some knives are labeled granton edge, but typically these knives have a taper ground edge and the blade has shallow divots cut out of it to reduce drag on the knife. These knives are also labeled scalloped edged by some vendors.

Heel - The heel is the part of the cutting edge farthest away from the point. Usually used when more weight and force are required to cut through (such as hard squashes or thin chicken bones).

Return - The return of the blade is the termination point of the heel. If the return is curved just right, then it allows a gentle rocking motion when preparing to make another stroke or slice with the knife. A well designed return can reduce fatigue and make repeated slicing a smooth cyclical motion instead of a staccato, paper cutter motion. If a finger guard is present on the knife, the return is often unable to be sharpened properly.

Spine - The spine is the top of the knife blade opposite of the cutting edge. A thick spine improves stability of the blade but may also make some cuts feel like you are driving a wedge instead of slicing with an efficient kitchen knife.

Bolster - The bolster is a collar that joins the blade of the knife to the handle. It's function is not to attach the blade to the handle, but to provide additional mass just forward of where the chef's hand is. This improves the stability, balance, and strength of the knife. Some bolsters are constructed with the blade (as in forged knives), while others are attached after the blade is constructed. In the past, it was easy to say that all such bolsters should be avoided because they were of poor quality, however many knife manufacturers have found ways of attaching bolsters to their blades with the same effectiveness as if they were constructed from the same piece of metal. Two notable examples of this are Zwilling J.A. Henckels (who manufacturers their forged blades with different metals for blade, bolster, and tang in a process they call Sintermetal Component Technology) and MAC Knife (who uses stamped steel for their blades). In general, knives which incorporate bolsters in their design are of higher quality than those which do not.

Bolster lip - The bolster lip is where the bolster tapers down to the blade. The lip can be steep, resulting in a sharp angle where the lip meets the blade or the lip can be gently sloped so it blends into the blade. Sharp angles can be a problem when washing the knife because small food particles may lodge in the corner and not be properly washed off. This may result in rusting, metal discoloration, or even bacterial growth if the material persists over time or water is trapped along with it. For this reason, preference should be given to knives with bolster lips that blend into the blade.

Finger guard - Often considered part of the bolster, the finger guard is designed to strengthen the heel of the knife, provide additional weight forward of the handle, and help a little to protect the finger from accidental slipping across the blade. The presence of the finger guard may make use of the heel easier by providing greater mass and stability, but at the same time may make it difficult to use the heel because it is physically larger and does not carry an edge. The use of the finger guard to strengthen the heel of the knife is generally unnecessary with modern steel formulations. A finger guard can be added to a stamped blade.

Tang - The tang is the part of the blade that actually extends into the handle of the knife. The handle is affixed to the blade through the tang. A full tang is a design where the tang is cut to the same size and shape as the handle and handle scales are affixed to both sides. Generally, a full tang is considered to be the most secure method of attaching a handle to a knife and is recommended for knives that will be seeing heavy duty action - like cleavers. Also common are encapsulated tangs which have handles molded onto a tang. Rat tail tangs are also enclosed within the handle and are generally affixed through the use of a bolt or pommel at the handle head. Half tang knives have a tang that only extends about halfway down the handle. These tangs are generally too short for knives that are used constantly or with a decent amount of force. Some half tang knives simply take the tangs and push them into the handle. These knives should be avoided. I recommend knives that have tangs of 3/4 length or full tang as these knifes will last the longest. The long tang gives the handle a better connection to the blade and whole knife will feel a little easier to control because of this connection and the extra weight it will provide to the back of the knife.

Scales - On knifes with riveted handles, the pieces of material (generally a type of wood) which are attached to the tang to form a handle are called the handle scales. The shape and material of the scales determines how the knife handle feels in the hand, if it will be comfortable after a long period or use, and whether or not it becomes slippery when wet or covered in fat. Scales should fit neatly behind the bolster and on both sides of the tang without slits or cracks (to ensure easy cleaning to avoid bacterial growth). The junction where the bolster and tang meet the scales should also be smooth (otherwise, the chef may develop blisters or rub their skin raw during use).

Rivets - Rivets are metal pins used to mechanically join the handle scales to the tang to form the handle. If the rivets are visible, they should be flush to the scales and no cracks should be present along the circle where the rivet meets the scale. Rivets are generally constructed with metal alloys that do not expand or contract much due to heat change to ensure a solid fit throughout the lifetime of the knife.

Handle guard - Many knives have a curvature that the end of the handle that is called a handle guard.

Butt or handle head - Butt is the terminal end of the handle of the knife. Handle head is another name for this part of the knife but is generally used when specifically discussing the handle of the knife.

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SUNGODDESS444
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PostPosted: Fri Nov 11, 2005 11:10 pm    Post subject: KNOWING YOUR KNIVES Reply with quote

THANK YOU FOR THE INFORMATION ON KNIVES. MAYBE YOU SHOULD OF ADDED HOW TO TAKE CARE AND SHARPEN THEM.
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TIANTED
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PostPosted: Sat Nov 12, 2005 3:47 pm    Post subject: sharp knives Reply with quote

Yes, as a serious cook, I have always had good and interesting knives. And, mine are always a bit dull. Partly from neglect, sloth and over use... partly because the full and perfect sharpening regimen has never been part of my world. I just want to have sharp knives and don't know what to do next..... Where is that perfect solution? There must be a shamen of steel out there....
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Maxlor
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PostPosted: Mon Nov 14, 2005 11:50 am    Post subject: Re: sharp knives Reply with quote

Maybe ceramic knifes are an option? They are advertized to stay sharp no matter what you do with them. We had one once, and the claim seemed to be true. Unfortunately, they don't seem to be as stable when sideways force is applied - With ours the tip broke off. But if you're careful, that shouldn't be that much of a problem?

What's the professional opinion on those knifes?
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PostPosted: Mon Nov 14, 2005 1:31 pm    Post subject: Sharpening of knives Reply with quote

I think the most important thing about knives is keeping them sharp. The only times I cut myself while cooking is when I have a blunt knife.

The best method I have found for keeping my knives sharp is using a proper ceramic knife sharpener like this: http://www.surfasonline.com/products/21705.cfm

It sharpens the knife perfectly every time and is very easy to use. Certainly a good investment for anyone who wants to look after their knives properly.
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Michael Chu



Joined: 10 May 2005
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Location: Austin, TX (USA)

PostPosted: Mon Nov 14, 2005 10:47 pm    Post subject: Reply with quote

This article only covers parts of a knife because there are more knife articles in the works. Next up is a comparison of eleven chef's knives. Sharpening is something I've been working on, but I'm not any further on that article than a series of notes and lots of practice with whetstones, but that will be coming up much later. I know everyone needs the answers now, but hopefully most people will be patient with me as I juggle work, writing, researching, and fact checking. Smile
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jagstyle



Joined: 08 Aug 2005
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PostPosted: Tue Nov 15, 2005 1:53 am    Post subject: Reply with quote

Michael Chu wrote:
Sharpening is something I've been working on, but I'm not any further on that article than a series of notes and lots of practice with whetstones, but that will be coming up much later.


Sweet! Which stones do you have?
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Michael Chu



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Location: Austin, TX (USA)

PostPosted: Tue Nov 15, 2005 5:47 am    Post subject: Reply with quote

jagstyle wrote:
Sweet! Which stones do you have?

I ended up getting the Norton stones you recommended: 220, 1000, 4000/8000 plus a flattening stone.

The 8000 puts a beautiful shine on the bevel. I've been practicing on old hand me down knives and bringing each one up to a pretty good level - but none have yet reached the keenness of my Japanese knives. I'm still working on my technique - I'm not perfectly consistent with my angle while drawing the blade across... practice practice practice.
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june
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PostPosted: Fri Nov 18, 2005 10:32 pm    Post subject: knives Reply with quote

Anyone know anything about a Santoki knife? Im considering returning it since I can't seem to get the "rocking" motion I usually use when slicing.
Also, for the person interested in the ceramic knives...think twice before you buy, you them and they BREAK! Both friends who owned them(past tense) chipped and/or scattered them.
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Michael Chu



Joined: 10 May 2005
Posts: 1619
Location: Austin, TX (USA)

PostPosted: Sat Nov 19, 2005 6:40 pm    Post subject: Re: knives Reply with quote

june wrote:
Anyone know anything about a Santoki knife? Im considering returning it since I can't seem to get the "rocking" motion I usually use when slicing.
Also, for the person interested in the ceramic knives...think twice before you buy, you them and they BREAK! Both friends who owned them(past tense) chipped and/or scattered them.

When buying a santoku for it's rocking motion, be sure to actually try the knife on a cutting board before committing to buying one. Some santokus just don't rock because of the curvature of the final few inches of the blade. If I remember correctly, the Wustof Grand Prix II and Henckels santokus have and abrupt stop while the Global and Wustof Le Corden Bleu santokus have an excellent return for that rocking motion you're looking for. My recommendation? Go to a store like Sur La Table where they have an area set up for you to try the knives on a butcher block. (Most stores will let you hold the knife but not actually slide the knife around on a cutting board to feel how it moves.)
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W Stockwell
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PostPosted: Mon Dec 05, 2005 9:06 pm    Post subject: Sharpening Reply with quote

There shouldn't be any mystery to sharpening. Take a look at http://razoredgesystems.com/ . His book explains exactly what you're trying to do when you sharpen a knife. Once you understand his method, you can sharpen most anything pretty easily and get it shaving sharp every time. I don't like his stones, but they do work . . .

BTW, since this is cooking for engineers, you should do a little research into hardening and tempering steels. Smile Knives need both as part of their heat treat, both forged and stamped.

Good description of the function of each part of the knife from a cooking point of view.
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Dave D
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PostPosted: Wed Dec 14, 2005 6:34 pm    Post subject: Knife Sharpening, etc. Reply with quote

Here is some of my experience with kitchen knives and sharpening...

As I understand it, the NSF requires stainless steel blades for restaurant use. Since these are also mass-produced by stamping and stock removal, the steel tends to be a little soft. A hard, forged, tool steel kitchen blade is rare any more, since it can't be used commercially and because folks have forgotten how to care for carbon steel.

On the other hand, I own a couple expensive hand-forged steel knives and one maker recommended the Lansky system for maintaining a constant grind angle. That's what I've used on my hunting knives.

For kitchen use, I use the Spyderco Tri-Angle Sharpmaker to sharpen plain and serrated blades. Since most kitchen blades are relatively soft for the reasons mentioned earlier, I sharpen frequently.

IMHO, unless you have spent $200-300 for a knife, there really isn't much reason to become a sharpening wizard. I expect my knives to slice tomatos, not a silk scarf falling through the air. <grin>

Cheers!
Dave
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Willyvrod
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PostPosted: Tue Mar 14, 2006 1:18 am    Post subject: cooking knifes Reply with quote

I have read all the post here, trying to get an idea about buying some cooking knifes for my wife. She is a GREAT COOK. Me not so good.
This is what I have done. I bought some cheap knifes. So, I can learn to keep them sharp. I got a 20 dollar kitchenAid chef knife. The box says it is some kind of 420 ja stainless steel forged. Also, I got a Chicago Cutlery Santoku knife and a paring knife, Also stainless steel forged.
Once I feel I can keep these sharp. I plan on getting some Wusthof. I think the Japanesse knifes are great , from all that I have read here. But the sharping thing seems to be a bit more involved than I am will to do.
However, For the price , the knifes I got do Alot better than What I have being using.
Thanks to everyones post. I now have a game plan
Thanks William!
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unknown
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PostPosted: Fri Apr 14, 2006 5:13 pm    Post subject: reply to Tianted Reply with quote

There is an entry on Egullet titled "Knife Maintenance and Sharpening" which has excellent information on sharpening and maintaining knives.
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guest
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PostPosted: Tue Oct 10, 2006 11:54 pm    Post subject: Whetstone versus Electric Knive Sharpeners Reply with quote

Which do you prefer when sharpening your best knives? A whetstone or an electric knife sharpener?
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