SciurusDoomus's Guide to Sharp Knives
I haven't seen a post like this on THP and I think everyone should know how to keep their knives sharp without ruining the knife or themselves financially.This is a long post, you've been warned.
Why you need to throw away your wedge grinder:
When most people think about sharpening knives in the kitchen, they think of those wedge grinders. You know, those things you grip in one hand and pull your knife though? All those “Miracle Diamond Super Edge” pieces of crap you see on T.V. for seven easy payments of $10.99 work on the same principle: They're two offset pieces of ceramic that basically strip off a huge amount of metal on the knife in an attempt to create a new edge. There are two problems with this sort of sharpener:
Why you need to buy stones:
Sharpening stones, whet stones, water stones, or just stones are integral to keeping your knives sharp. Stones allow you freedom of the angle at which you grind the edge, they allow you to grind off minute amounts of metal at a time (lengthening the knife's life), and they almost always get a more precise edge that cuts better than other “quick” grind methods.
What sorts of stones do you need?
Stones can be broken into two main catagories: natural and synthetic. Natural stones mostly come from Arkansas and Japan, places that have rock layers that consist of very small particles bound loosely together. When steel is rubbed over these stones, the particles are pulled away from the rest of the stone as they grind against the steel. This sharpens the steel as well as exposes new, sharp particles on the surface of the stone. Natural stones tend to be more expensive as they are becoming more and more rare, but some people prefer them for their beauty and because they can go up to very very high grits. Synthetic stones are basically ceramic particles bound together with an adhesive. They operate on the same principle as natural stones but they are cheaper and have very consistent grit sizes, meaning you will get a very consistent grind on your knife.
Many people own several stones, but I get away with two: A coarse stone for reshaping lost edges and a fine stone for finishing/polishing/honing/stropping the knife. My coarse stone is a 240/320 grit and the fine stone is a 1000/6000 grit. Using just these stones, you can get almost any knife razor sharp with practice.
Grit:
Grit simply refers to the size of the particles of the stone. A high number means a smaller particle and a finer grind on the knife. Typically grits <500 are used for regrinding a lost edge and take off a lot of metal. ~1000 grit stones are used for fine tuning and shaping of the edge and finally 4000+ stones are typically used for polishing and only remove a small amount of metal at a time.
Edge Angle:
Edge angle is simply the angle between the two edges of a knife. Most knives vary between 15 and 35 degrees. Obviously, a very small angle results in a thin edge that is prone to bending, but when sharp and honed, can cut very finely. Razors are typically in the range of 15 to 20 degrees. On the other end, survival knives are typically ground at 30 to 35 degrees. This fat edge is stronger and allows the knife to be batonned through logs without bending or dulling too quickly. The middle ground (20 to 25 degrees) is where most every day carry (EDC) knives, pocket knives, and kitchen knives settle. Note that edge angle refers not to the angle between the two sides of an edge, but to the angle between one edge and the middle of the spine of a knife. If you were to create a 20 degree edge, you would hold the knife 20 degrees up from the stone, not 10.
How to Grind:
There are several different methods to grind an edge. They apply to creating a new edge as well as refining one that already exists. Before using any method, it's always good to lubricate the stone in either oil or water. This is done by first soaking the stone for a long time in the lubricant and then applying it with a finger every now and again during sharpening. Stones are porous and will soak up a lot of lubricant by themselves. This will reduce the amount you need to apply by hand during sharpening later.
Note that for most synthetic stones it doesn't matter whether you use oil or water but you should never use one and then the other on the same stone. I use water since it's cheaper and because oil is messy and there's no tangible benefit. Also, make sure that you put a rag or paper towel underneath the stone to prevent from moving around during sharpening. The point of lubricant is to suspend the dulled stone particulate and metal filings in the lubricant. This is called "cutting swarf," "slurry," "paste," or "mud." When grinding, this swarf/slurry/paste/mud will help sharpen, polish, and lubricate the blade as it moves across the stone. Some people prefer to clean slurry away but most people keep it on the stone until they're done sharpening.
Lie the flat of the blade on the stone and slowly tilt it upwards until you feel it stop. This is call “finding the edge” and once you get a feel for your knives, you'll be able to find it quickly. Practice a few times before flipping the knife around and finding the edge on the other side. It is critical that you maintain the same angle with your hand as you sharpen or you risk wasting time and metal. When you sharpen, you'll be pushing the knife so that it's sharpening edge first. Imagine that you're trying to shave off the top layer of the stone. (When you hone, you'll go the other way, as if you're trying to put that layer of stone back with a trowel.)
Once you've found the edge, you have a few options. Some people prefer moving the knife in a figure eight over the length of the stone or in small circles. I prefer long lateral strokes across the stone since it wears the stone evenly and reduces the need to grind the stone flat later. You can use one hand or two to push the knife; I generally use two, holding the knife in my dominant hand to maintain the angle and pushing only with my non-dominant hand. However, as long as you can keep your angle, it doesn't matter at all how you hold it.
Pressure is also very important. The amount of pressure with which you start grinding typically depends on how much metal to intend to take off the knife by the end. Generally, I apply pressure slowly until I feel the knife dragging slightly against the stone as I draw it. You'll quickly get a feel for the ratio of pressure to metal removal. As you grind, slowly lighten the pressure until your last few strokes are with just the weight of the knife (or even less if you can do that and maintain the angle.) This lightening of pressure will run the dulled particles over the edge and slightly buff and hone the edge, reducing the time you spend stropping or honing later.
If you're making lateral strokes back and forth across the stone, your grinding time can be shortened by stroking 5 times on one side and then 5 on the other. Do this a few times and then reduce the stroke number to 4, 3, etc. When you get to the point where you are doing one stroke per side, make sure you're putting very little pressure on the blade and keeping your angle religiously. When you're finished, you can “strop” the blade by drawing it backwards (i.e. the spine toward you) along the stone. This will hone/straighten the edge. This is like what a chef or barber does to his knife. A chef will use a long metal hone and a barber typically uses a leather strop. The point of stropping is to line up an edge that is already sharp. This will give you a cleaner cut.
Stone Care:
After every use, stones must be scrubbed gently under running water to remove all slurry and metal particulate from their surfaces. Remember that higher grit stones tend to be softer (and more expensive!) and you should therefore be more delicate with them.
Eventually, your stones will become uneven on one side or develop a scooped out “belly” in the middle where most grinding takes place. To correct this, there are many plate grinders or special stones known as “Nagura” stones which are ground over the top to flatten your stones. Yes, this takes away precious material, but a stone that isn't flat won't sharpen reliably. Most people who use synthetic stones use a diamond sharpener to flatten their stones as coarse diamond sharpeners take less time to remove stone material and will never lose their own flatness like another stone might. The only drawback to diamond sharpeners is that they tend to be expensive. However, they will take a lot of abuse before they lose efficacy.
This was a brief look into knife care. There are other techniques such as stropping with a piece of leather and stropping compound, honing with a steel chef's hone, and tarnish protection, but they take up too much room for this post. I hope you enjoyed this and for Pete's sake throw out your damn wedge grinder!
May your knives never dull,
S
P.S. Here are the stones I use:
240/320 Grit stone:
http://www.amazon.com/gp/product/B003Y3BM84/ref=oh_details_o01_s00_i01?ie=UTF8&psc=1
1000/6000 Grit stone:
http://www.amazon.com/gp/product/B0037MCLLO/ref=oh_details_o02_s00_i00?ie=UTF8&psc=1
I haven't seen a post like this on THP and I think everyone should know how to keep their knives sharp without ruining the knife or themselves financially.This is a long post, you've been warned.
Why you need to throw away your wedge grinder:
When most people think about sharpening knives in the kitchen, they think of those wedge grinders. You know, those things you grip in one hand and pull your knife though? All those “Miracle Diamond Super Edge” pieces of crap you see on T.V. for seven easy payments of $10.99 work on the same principle: They're two offset pieces of ceramic that basically strip off a huge amount of metal on the knife in an attempt to create a new edge. There are two problems with this sort of sharpener:
They create a new edge where one usually isn't needed: This means that you're not sharpening the edge that exists, but creating a new one every time. It also means you're limited to the edge angle that's determined by the sharpener. This is fine if you're sharpening your lawnmower blade, but it offers no freedom to the user about how their knife works
They remove an enormous amount of metal, reducing the lifespan of your knife. In addition to this, they also tend to “scallop” the edge, removing metal unevenly which will give you ragged, ugly cuts and a knife that doesn't feel smooth when cutting
Why you need to buy stones:
Sharpening stones, whet stones, water stones, or just stones are integral to keeping your knives sharp. Stones allow you freedom of the angle at which you grind the edge, they allow you to grind off minute amounts of metal at a time (lengthening the knife's life), and they almost always get a more precise edge that cuts better than other “quick” grind methods.
What sorts of stones do you need?
Stones can be broken into two main catagories: natural and synthetic. Natural stones mostly come from Arkansas and Japan, places that have rock layers that consist of very small particles bound loosely together. When steel is rubbed over these stones, the particles are pulled away from the rest of the stone as they grind against the steel. This sharpens the steel as well as exposes new, sharp particles on the surface of the stone. Natural stones tend to be more expensive as they are becoming more and more rare, but some people prefer them for their beauty and because they can go up to very very high grits. Synthetic stones are basically ceramic particles bound together with an adhesive. They operate on the same principle as natural stones but they are cheaper and have very consistent grit sizes, meaning you will get a very consistent grind on your knife.
Many people own several stones, but I get away with two: A coarse stone for reshaping lost edges and a fine stone for finishing/polishing/honing/stropping the knife. My coarse stone is a 240/320 grit and the fine stone is a 1000/6000 grit. Using just these stones, you can get almost any knife razor sharp with practice.
Grit:
Grit simply refers to the size of the particles of the stone. A high number means a smaller particle and a finer grind on the knife. Typically grits <500 are used for regrinding a lost edge and take off a lot of metal. ~1000 grit stones are used for fine tuning and shaping of the edge and finally 4000+ stones are typically used for polishing and only remove a small amount of metal at a time.
Edge Angle:
Edge angle is simply the angle between the two edges of a knife. Most knives vary between 15 and 35 degrees. Obviously, a very small angle results in a thin edge that is prone to bending, but when sharp and honed, can cut very finely. Razors are typically in the range of 15 to 20 degrees. On the other end, survival knives are typically ground at 30 to 35 degrees. This fat edge is stronger and allows the knife to be batonned through logs without bending or dulling too quickly. The middle ground (20 to 25 degrees) is where most every day carry (EDC) knives, pocket knives, and kitchen knives settle. Note that edge angle refers not to the angle between the two sides of an edge, but to the angle between one edge and the middle of the spine of a knife. If you were to create a 20 degree edge, you would hold the knife 20 degrees up from the stone, not 10.
How to Grind:
There are several different methods to grind an edge. They apply to creating a new edge as well as refining one that already exists. Before using any method, it's always good to lubricate the stone in either oil or water. This is done by first soaking the stone for a long time in the lubricant and then applying it with a finger every now and again during sharpening. Stones are porous and will soak up a lot of lubricant by themselves. This will reduce the amount you need to apply by hand during sharpening later.
Note that for most synthetic stones it doesn't matter whether you use oil or water but you should never use one and then the other on the same stone. I use water since it's cheaper and because oil is messy and there's no tangible benefit. Also, make sure that you put a rag or paper towel underneath the stone to prevent from moving around during sharpening. The point of lubricant is to suspend the dulled stone particulate and metal filings in the lubricant. This is called "cutting swarf," "slurry," "paste," or "mud." When grinding, this swarf/slurry/paste/mud will help sharpen, polish, and lubricate the blade as it moves across the stone. Some people prefer to clean slurry away but most people keep it on the stone until they're done sharpening.
Lie the flat of the blade on the stone and slowly tilt it upwards until you feel it stop. This is call “finding the edge” and once you get a feel for your knives, you'll be able to find it quickly. Practice a few times before flipping the knife around and finding the edge on the other side. It is critical that you maintain the same angle with your hand as you sharpen or you risk wasting time and metal. When you sharpen, you'll be pushing the knife so that it's sharpening edge first. Imagine that you're trying to shave off the top layer of the stone. (When you hone, you'll go the other way, as if you're trying to put that layer of stone back with a trowel.)
Once you've found the edge, you have a few options. Some people prefer moving the knife in a figure eight over the length of the stone or in small circles. I prefer long lateral strokes across the stone since it wears the stone evenly and reduces the need to grind the stone flat later. You can use one hand or two to push the knife; I generally use two, holding the knife in my dominant hand to maintain the angle and pushing only with my non-dominant hand. However, as long as you can keep your angle, it doesn't matter at all how you hold it.
Pressure is also very important. The amount of pressure with which you start grinding typically depends on how much metal to intend to take off the knife by the end. Generally, I apply pressure slowly until I feel the knife dragging slightly against the stone as I draw it. You'll quickly get a feel for the ratio of pressure to metal removal. As you grind, slowly lighten the pressure until your last few strokes are with just the weight of the knife (or even less if you can do that and maintain the angle.) This lightening of pressure will run the dulled particles over the edge and slightly buff and hone the edge, reducing the time you spend stropping or honing later.
If you're making lateral strokes back and forth across the stone, your grinding time can be shortened by stroking 5 times on one side and then 5 on the other. Do this a few times and then reduce the stroke number to 4, 3, etc. When you get to the point where you are doing one stroke per side, make sure you're putting very little pressure on the blade and keeping your angle religiously. When you're finished, you can “strop” the blade by drawing it backwards (i.e. the spine toward you) along the stone. This will hone/straighten the edge. This is like what a chef or barber does to his knife. A chef will use a long metal hone and a barber typically uses a leather strop. The point of stropping is to line up an edge that is already sharp. This will give you a cleaner cut.
Stone Care:
After every use, stones must be scrubbed gently under running water to remove all slurry and metal particulate from their surfaces. Remember that higher grit stones tend to be softer (and more expensive!) and you should therefore be more delicate with them.
Eventually, your stones will become uneven on one side or develop a scooped out “belly” in the middle where most grinding takes place. To correct this, there are many plate grinders or special stones known as “Nagura” stones which are ground over the top to flatten your stones. Yes, this takes away precious material, but a stone that isn't flat won't sharpen reliably. Most people who use synthetic stones use a diamond sharpener to flatten their stones as coarse diamond sharpeners take less time to remove stone material and will never lose their own flatness like another stone might. The only drawback to diamond sharpeners is that they tend to be expensive. However, they will take a lot of abuse before they lose efficacy.
This was a brief look into knife care. There are other techniques such as stropping with a piece of leather and stropping compound, honing with a steel chef's hone, and tarnish protection, but they take up too much room for this post. I hope you enjoyed this and for Pete's sake throw out your damn wedge grinder!
May your knives never dull,
S
P.S. Here are the stones I use:
240/320 Grit stone:
http://www.amazon.com/gp/product/B003Y3BM84/ref=oh_details_o01_s00_i01?ie=UTF8&psc=1
1000/6000 Grit stone:
http://www.amazon.com/gp/product/B0037MCLLO/ref=oh_details_o02_s00_i00?ie=UTF8&psc=1
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