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Knife Sharpening Tutorial
by Proteas of Newgrounds.com
My intent with this article is to put forth, in no uncertain terms, how to sharpen a knife. I feel this is needed as the very art and skill of knife sharpening is surrounded in far more mysticism and bullshit than is needed, and it only serves to stroke the ego of self claimed "experts" who would seek to capitalize on the general public's ignorance for their own glory and financial profit. Not only do I intend to tell you how to sharpen a knife, I intend to also tell you the why behind the method, what not to do, as well as how to pick out a sharpening stone most suited for your own purposes.
This article is merely a compendium of knowledge culled from internet message boards, free online articles, Q & A sessions with fellow knife collectors, and my own experimentation. The information I provide here was found for free and is being presented for free, so please feel free to pass this along to your friends and repost it. I am being honest with you the reader, so I would hope that you would be honest and NOT try to rip me off by claiming this work as yours for scholastic purposes or to impress your buddies at work.
Please exercise common sense at all times when reading this article or practicing the methods proscribed herein. If you have any further questions, you can contact me at firstname.lastname@example.org, but please don't come crying to me if you cut yourself, lose a finger or limb, or ruin a perfectly good knife or sword that was passed down to you through the family for generations on end, because I don't want to hear it.
Table of Contents;
Section one; Knife Steels and Grinds.
Section two; Sharpening the knife
Section three; choosing the right sharpening stone
Section four; sharpening aids
Section one; knife steels and grinds.
This particular section of the tutorial is rather short. The most commonly used knife steel categories are Stainless Steel, and Carbon Steel. Stainless steel for knives are most commonly available in 4 grades;
- 304 Series (cutlery grade),
- 316 Series ("Surgical" or "Marine" grade)
- 420 Series (quit laughing)
- 440 Series (high grade stainless).
Each type steel (carbon steel included) has about the same difficulty in sharpening, but each one holds an edge differently. 440 series is touted as being the best for knife blades and holds its edge excellently, and is the choice steel for higher quality knives and razor blades. The different series numbers are determined by the amount of certain elements contained in the steel, which indicate the individual chemical components in the steel itself. Unless you're a chemist, don't worry about it.
Carbon Steel is sold in 1095 Series, sometimes referred to as "Tool Steel," and holds an excellent edge. But unlike Stainless steel, Carbon steel will rust and develop a patina over time. Carbon Steel knives that are stronger than the 1095 series are available, typically in the form of mid to higher grade chef's knives which are more difficult to sharpen than your average knife.
Damascus steel is mentioned here at this point solely for completeness. Damascus steel is made from folding of two different steels folded together numerous times, and bares a distinctive lined pattern running the length of the blade. The more times the blade steel is folded, the stronger the steel, the better its ability to hold an edge, and the sharper that it can be made. This is/was the preferred steel for the historical Samurai swords of ancient Japan, and is revered by many knife collectors for the beauty and strength it adds to a blade. It is available in pocket knives, swords, even straight razors, but the cost can be prohibitively expensive due to the labor intensive process of making a Damascus steel blade.
If you look at the average knife, you will notice that it is not simply a flat piece of steel, it is beveled to come to a point before the actual cutting edge. This is the grind of the knife itself. Most of the knives that you will come across will be "V" ground, in that the bevel takes the shape of the letter V when viewed at the end of the blade. Different manufacturers will grind their knives differently depending on the style of the blade and the quality of the steel (some knives will be v-ground from the middle of the blade down, some will get close to the edge and start, and some will start as far back as the back edge of the knife). The grind - along with the strength of the steel - are the two determining factors of how sharp the knife can be made.
Just remember; you can make any knife sharp, but you cannot make every knife razor sharp, and not every knife is capable of holding such an edge for very long.
Section two; sharpening the knife.
The key to sharpening any knife, regardless the grade of steel it's made from or its intended purpose, is to maintain proper angle alignment while sharpening. If you should deviate from your chosen sharpening angle while sharpening, you can either (a) blunt the edge if you should raise the knife up to far or (b) do nothing to the edge should you lower it too far. Think of it like sanding the edge of a table; if you don't keep the sandpaper 90 degrees flush with the top, the edge will look crooked; you just want to maintain a 90 angle.
How do you determine the correct angle for your knife? Usually a 22 degree angle is sufficient for most cutting and slicing needs. Razor knives (not to be confused with straight razors) will take a lower sharpening angle, while skinning knifes will take a higher angle, but both ends of the extreme typically stay between a range of 15 to 30 degrees. Anything greater than 30 degrees will be used in a chopping implement such as a lawn mowing blade, machete, axe... you get the general idea.
A good way to determine a 22 degree angle is to take the knife and hold the edge against the stone at a 45 degree angle, then lower the back edge down by half, or go a bit lower or higher depending on your particular need. Be sure to hold your thumb or pointer finger against the back edge of the knife blade when you achieve your desired angle against your abrasive of choice, as this will ensure consistency in your work. I don't recommend free hand sharpening without a thumb or forefinger in place on the spine of the knife unless you are DEAD sure that your hand is steady enough to maintain your angle of choice, as would be the situation when working with a kitchen steel (which we'll get to later).
A common method for sharpening is to make a sweeping pass across the top of the stone as if you were attempting to slice off a thin layer of the stone. This is okay, and if you feel comfortable doing it, then by all means. However, a more efficient way to hand sharpen is take and make a small circular motion across the top of the stone, moving back and further across the top of the stone. This speeds up the process of sharpening considerably, and is a good method for starting an edge on a knife, whereas the sweep motion is good for light touchups and taking off a wire edge (which I will describe later).
A common mistake made when hand sharpening any knife is the idea that a consistently difficult feel is needed, as if you want to feel abrasive through the blade. So, people will adjust their blade angle for this and keep going, thereby dulling their knife even further. If you maintain the correct angle, the motion will feel smooth as time goes on (although it certainly won't sound like it).
The way to tell how you are coming along with your knife is take it in hand (in the same manner you would cut with it) with the cutting edge facing toward you. Take your thumb and gently -- let me emphasize this, GENTLY -- brush it across the edge of the blade perpendicularly. Exercise extreme caution and common sense when doing this; do not draw your thumb down the length of the blade as you will slice your thumb open. What you are feeling for when you do this is the edge itself as it goes across the ridges in your thumb; a coarsely sharpened edge will feel rough and extremely sharp (it isn't), a finely honed blade will feel fine and slightly dull, but it will irritate the skin slightly as it goes across. To get the general idea, try this with two different box cutter blades; one dull and one sharp.
While you have the blade in hand, you also will want to take a moment and set your thumb against on side of the blade and brush it up and over the top in a similar manner to how you felt the sharpness of the blade. Do both sides when you do this, what you are feeling for is what's called a "Wire Edge," which is a sign that you've taken off a sufficient amount of steel as to create a paper thin cutting edge, and has folded over. Using the thumb brush test, the side of the very top edge will feel rough on one side and smooth on the other side, with the wire edge leaning toward the rougher side. You can use the knife at this point, but after a few uses the edge will degrade and you'll have to sharpen again. What you want to do here is gently sharpen the knife evenly on both sides to eliminate the wire, and then move on to your next finest step.
If you are working on a kitchen knife, do not put your finished knife in the dishwasher under any circumstances if you intend to keep the edge you put on it. Leaving the knife in hot water for extended periods of time will ruin a knife's sharp edge; instead, hand-wash the knife and towel dry it.
And remember, the sharper the knife, the thinner the steel is at the cutting edge. For chopping implements such as machete's and axes, you don't want to go through to the finest abrasive you have on hand because the edge may simply fold over after one good swing (true Damascus steel samurai swords can handle being sharpened with fine abrasives, however).
Section three; choosing the right sharpening stone.
First and foremost, there is no perfect abrasive for sharpening knives with; it's just what you prefer and what works for you. Anything can be used to sharpen a knife so long as it has a rough enough texture to it to take off metal with.
I categorize abrasives into the following three categories; this is not the universally accepted rule so take it as ye will; grinding, sharpening/honing, and polishing. Grinding establishes the cutting edge of a knife and is typically done with extremely coarse abrasives, you can get a basic but very rough cutting edge when grinding. Sharpening is taking the coarsely ground cutting edge and focusing the edge into a very fine cutting edge, thus you are honing the edge. And finally, polishing, which is taking a micro-thin layer of metal off of the blade to create an actual razor sharp edge.
A common tool for sharpening knives is the Flat File, which you can easily at any hardware store (even Wal-Mart) for next to nothing. A flat file is basically a piece of case hardened steel that has metal ridges cut into it, and it can and will take off large amounts of metal, so this is definitely a grinding tool. If you should get a file, I recommend getting a Single Cut Bastard/Mill file or a Smooth file if you can find one in a flat style. The advantage is that it's a good way to start an edge, the disadvantage is that it's difficult to lay one flat on a table and use it as a bench stone, so you have to hold the knife in one hand and file it with the other. Because files are case hardened, they will last for many years, and the steel itself actually makes for very good knives once its teeth have been worn off.
The next item is manmade abrasives such as Corundum. Corundum typically comes in coarse to medium and sometimes fine grades, but all typically will stay under the 300 grit range. You can find these in most hardware stores and some hunting stores, and they can be used dry or wet, although using the stone wet is recommended as it keeps the stone itself from becoming clogged with metal filings. The advantage of Corundum is that (like the flat file), it's cheap and readily available, and it can put a finer edge on a knife that a flat file can. The disadvantage is that the stone itself can become clogged with metal filings over time, you can work a valley into it from focusing on one spot for far too long (thus reducing its effectiveness), and... the abrasive along the surface itself can go dull, and refinishing the stone is not cost effective. This is the type of abrasive most commonly found in the wheels of bench grinders as well.
Man-Made or Industrial Diamond bench stones are typically only available at hunting stores, although some hardware stores will carry a small selection of them, and they can be a bit pricey depending on the size of bench stone you're looking for. You can find diamond stones running the gamut from very coarse to SUPER fine, depending on your need. Don't get the wrong idea; you won't actually be holding a carat's worth of gem-grade diamond. Instead, diamond bench stones typically consist of a plastic holder with a metal matrix on top, with the metal matrix itself coated in multiple micro thin layers of crushed diamond particles. Diamond sharpeners are great because the abrasive grit itself does not wear out, and as such can be used on higher-carbon-steel knives that would be difficult to sharpen otherwise. The disadvantage is that the glue holding the diamonds to the matrix can weaken over time, and you will start to lose the grit itself, thereby decreasing the efficiency of the sharpener itself.
Tungsten Carbide is actually the second hardest man-made material next to Industrial Diamond; however, you won't see it advertised as such or by its proper name. Tungsten Carbide is the metal that is used as a coarse abrasive in most of the pre-angled "pull through" style knife sharpeners, and is actually a component piece in some knife steels and the main component in Military issue Armor-Piercing-Rounds. The downside is that this abrasive is typically only available in the pull-through styled sharpeners; free-hand files that contain this element do exist but are a bit difficult to find in stores. Tungsten Carbide in this form is VERY difficult to wear out.
Ceramic stones are another manmade abrasive, and are usually the other component in pull-through style sharpeners. Ceramics are typically found in rod form, although flat bench-stone style pieces do exist. This particular abrasive is very fine and used to as a final step in most sharpening kits, and is very difficult to wear out.
"Arkansas" Stones are a natural stone from the Ouachita Mountains in Arkansas, and are formed from a geographically unique mineral called Novaculite. Arkansas stones are not graded the same way that other abrasives are, because they are actual pieces of rock out of the ground and not a granulated form of abrasive that can be easily classified. However, they are graded from coarse to fine as follows; Soft, Hard, Surgical Black, and Opalescent. Arkansas Stones are a specialized product, and while the Soft stone is easily available at most hunting stores, the latter three are a bit more difficult to come by and a LOT more expensive than the Soft Stone. The advantage of an Arkansas stone is that it polishes the edge to a smooth finish as you sharpen, thus resulting in a finer edge, AND the abrasive is consistent through and through. However, as a stone, it shares similar faults as corundum stone would have (save for the fact that its grit is consistent through and through).
Japanese Water Stones are mentioned here for inclusivity when discussing natural sharpening stones. Much like the Arkansas stones, Japanese water stones are capable of putting a keen polished edge on a knife. Unlike Arkansas stones, however, they are graded using actual grit numbers which are fairly consistent from one stone to the next. The reason for this is because where an Arkansas stone is cut from the ground whole; a Japanese Water Stone is actually made, utilizing different grades of crushed stone grit particles suspended in a clay matrix. This type of stone has the significant advantage over all others in that they are available in far more grades than other sharpening stones (the Japanese woodworker catalog carries them from a very coarse 80 grit on up to a mirror smooth 12000 grit), the only drawback being that the clay causes the stone to be softer than others, which can lead to valleys being ground into it. Unlike other stones, a Japanese water stone CAN be flattened and refinished.
Sandpaper is generally a heavyweight paper that is treated with epoxy and coated with abrasive grit particles, generally silicon carbide or aluminum oxide. It runs the gamut from 36 grit (which I would not touch any knife with) for stripping paint on up to 2000 grit which is used in preparation for final automotive paint layers, and beyond that for sandpaper sharpening fine woodworking tools (also available at the Japanese Woodworker Catalogue). Unlike the Arkansas and Japanese Water stones, Sandpaper merely sharpens, it does NOT polish a knife blade at all, and like the flat file it can significantly reduce the useable life of your blade. The advantage of sandpaper is that it's (1) cheap, (2) readily available, and (3) easy to replace. The disadvantage is that it requires a mild adhesive to affix it to a dead flat and level surface, which must be had in order for this abrasive to work correctly.
Jeweler's Rouge (Added 9/4/08)
This is something I've learned about only recently. Jeweler's rouge is a wax compound that contains ferric oxide, a type of fine rust. The combination of micro-fine metallic particles and wax acts together to create a fine polishing effect, suitable for buffing and polishing of metals ranging from hardened steel to jewelry based on the size of the particles in rouge itself. When used in knife sharpening, this can be useful as a final step in sharpening if you want a keen edge. The method for using rouge is similar to the one used sandpaper; apply a piece of paper to a flat surface, apply the rouge to the paper, and start sharpening.
The last two items are what I consider to be polishing abrasives more than anything, and they are the Kitchen Steel and the Barber's Strap. The kitchen steel is typically a 12 inch long steel rod (quit laughing you pervert) that has about a 600 grit/mesh pattern pressed into it, and this is used to touch up the edge of an already sharp knife before use. You can use a kitchen steel to put the final edge on a knife but it can't be used to start an edge on a knife.
The barber's strap is typically the same way; it usually consists of two lengths of material (typically a cotton fiber "coarse" strap and a leather "fine" strap), and in the days of old this was the preferred tool for putting the final edge on a straight razor. If you have one or have access to one, you can use a barber's strap to put the final edge on a knife blade provided you hold the strap taught and maintain proper angle. If you don't have access to a barber's strap, you can use the rough side of an old leather belt as a reasonable substitute (make sure it's a solid leather belt, not woven).
Each individual type of sharpener will work either dry or wet (save for the barber's strap and kitchen steel, use these dry), usually utilizing either water or petroleum based oil as lubrication. The purpose of lubricating a stone when sharpening is to help metal shavings move off of the surface and keep the filing from clogging up the pores of the stone itself.
Section four; sharpening aids.
All this being said, don't feel discouraged if you cannot hand sharpen a knife. I can do it myself, but only with some considerable difficulty (nobody's perfect). Here you will find a short list of some useful sharpening aids to consider.
Pull through sharpeners
Typically this will be the tungsten carbide/ceramic rod combination we discussed earlier. Some companies make use of ceramic wheels in their pull through sharpeners, and I on one occasion saw a pull through that utilized two sections of a kitchen steel for sharpening.
Gerber makes a pull through sharpener through the Bud K catalogue that utilizes a pair of brown ceramic rods for a coarse, and this is my personal favorite as it pulls off enough metal to be truly effective. Why? Because while Tungsten Carbide is ranked as second Man-Made Diamond in terms of hardness, the typical piece of Tungsten Carbide found in pull through sharpeners does not have a coarse enough pattern pressed into it to be that effective as a coarse abrasive. But, each knife is different; one knife may come out sharp enough to shave with while the next won't be affected at all. You have to experiment with these.
Angle guide systems
These are a bit difficult to explain on paper if you've never seen one, but here goes. An angle guide system is basically two L-brackets that clamp to the back edge of a knife, with a mounted abrasive and guide rod being used to sharpen the knife while being held at one of four angles by the clamp itself. This type of sharpener was engineered by the Lansky Company in the late 1970's, and has since been imitated by Smith's Sharpeners and DMT. Lansky is unique in that they offer corundum, Arkansas, and diamond stones for use with their system whereas Smiths and DMT are limited to just Diamond and a ceramic. DMT is a standout as their clamp system can also be used to sharpen a knife on a bench stone with a sweeping motion (just set one edge of the clamp on a table, adjust for height and bevel, and then pull the knife the length of the stone).
This last one is a bit on the obscure side. But what it basically consists of is a triangular metal sleeve with a plastic insert that fits over the back edge of a knife, and when the knife is laid against your stone, will hold the knife at a predetermined angle. It acts like a binder/bulldog clip that you would get at an office supply store, and are made specifically for use with the MinoSharp brand of knives, but can be used on regular kitchen knives as well.
Rolling Knife Sharpener (Added on 8/20/08)
This is something I've just recently discovered, and I am AMAZED at how well these work. It's basically a small wheel of corundum (about 120 grit), with what looks like two reversed yo-yo halve attached to it on either side. The inside of the plastic wheel acts as an angle guide so you can hold the knife against the stone at the correct angle, then you just roll the wheel (knife and all) along the counter so the stone runs the length of the blade as it turns. It also works pretty well for free-hand sharpening, as you can just run it down the length of the blade and get the same effect (which I prefer). The size of this tool makes it well suited for kitchen knives and larger hunting knives, not really well suited for use with pocket knives though.
And that's about it. Again, if you have any further questions, feel free to drop me a line at email@example.com.