CH. 9 SHARPENING AND KNIFE CARE
Sharpening the edge of your blade is the last step in making your knife. Like most things in knifemaking, every maker has their preferred method for sharpening. In my opinion, the best method for sharpening is one that leaves you with a useful knife. A knife is only as good as how well it performs its function, and there are very few knives that were designed to be dull.
After all the work that you’ve put into making your knife, it’s almost time to head out into the world and put it to the test. With proper care, a knife can last a lifetime. Learning to safely and effectively use your blade can allow you to get the most out of your functional work of art.
HAND SHARPENING A BLADE IN FRONT OF THE SHOP. SHARPENING IS ALMOST A FORM OF MEDITATION, REQUIRING PATIENCE AND CONTROLLED CONSISTENCY.
SHARPENING TOOLS
The sheer number of different sharpeners available on the market can be overwhelming. In my opinion, the confusion this can create is part of the reason so many people carry dull knives. Different sharpeners require different techniques, but the principles of sharpening remain the same. The following are some of the more common styles of sharpeners available.
STONES
There is a variety of different types of stones available for sharpening, and each has advantages and disadvantages. Some stones require oil or water to be used as a lubricant. This lubricant reduces the friction of grinding and helps to remove the swarf to keep the stone working effectively. Swarf is the name given to the small metal dust that is abraded off your blade during the sharpening process.
Each stone will be a specific grit. You’ll need to be able to move from a coarser stone to a finer stone to complete the process, so get a few stones of varying grits.
JUST A HANDFUL OF THE MANY SHARPENING TOOLS AVAILABLE ON THE MARKET
Waterstones
Waterstones require water to be used as a lubricant. They are the softest of the sharpening stones, and as they are used, the surface is constantly wearing away. This exposes new, fresh abrasive and makes them great for sharpening. This stone dust, or slurry, also works to polish the bevel. The constant wear creates an indentation in the top of the stone, which needs to be flattened frequently to maintain a good surface for grinding.
A STONE IS THE TOOL MOST PEOPLE PICTURE WHEN THEY THINK OF SHARPENING A KNIFE.
Japanese waterstones: Japanese waterstones are a kind of natural waterstone that is mined in Japan, and they need to be soaked in water for twenty-four hours before they can be used. They are widely renowned as some of the best-quality stones in the world but are rare and, as a result, expensive.
Synthetic waterstones: Synthetic waterstones are made by combining aluminum oxide with resin. While some die-hard waterstone users prefer the natural stone, most professionals agree that synthetic waterstones perform just as well.
STONES THAT ARE MADE FOR USE ON A FLAT SURFACE ARE CALLED BENCH STONES. SMALLER STONES THAT ARE HANDHELD ARE CALLED POCKET STONES. THIS DIAMOND POCKET STONE IS CARRIED BY THE AUTHOR IN THE FIELD AND HAS STOOD UP WELL TO THE ABUSE OF TRAVELING AROUND THE WORLD.
Oilstones
Oilstones are harder than waterstones and require oil instead of water as a lubricant. This can be a bit messier, and it can be less convenient to have oil readily available to use, especially in the field. They don’t wear down as fast as waterstones, but they also don’t polish quite as well.
Arkansas stones: This is the most common kind of natural stone and is a type of novaculite that is mined in the United States. It comes in several grades, from coarse to fine. They tend to cut a bit more slowly than man-made stones but can produce a nice polished edge.
Aluminum oxide oilstones: Also known as India stones, these synthetic stones are made from aluminum oxide and resin. Unlike synthetic waterstones, the resin used is much harder and doesn’t wear as quickly. The quality of these stones can vary greatly, but they are less expensive than Arkansas stones.
Silicon oxide oilstones: These stones are the fastest cutting of the three kinds of oilstones. They don’t make quite as fine of an edge but are great for extremely dull knives or for starting your edge before progressing to something finer.
Ceramic Stones
Ceramic stones are made by combining ceramic powder and aluminum oxide. They don’t require any lubrication to use, tend to be more expensive than a lot of stones, but don’t wear quickly and can last a long time. They can be brittle and usually are only available in finer grits.
Diamond Stones
These stones utilize small, man-made diamonds to sharpen the steel. They don’t require any lubrication, and because the surface isn’t being abraded, they don’t lose their flatness. While convenient and fast, they don’t create quite as good a polish as waterstones.
GUIDES
There are a number of different guides available on the market designed to hold your blade at a specific angle. You can then run your blade across a stone and avoid the learning curve that comes with figuring out how to maintain a consistent angle.
THE WORK SHARP SHARPENER IS AN EXAMPLE OF AN ELECTRIC SHARPENER DESIGNED BY WORLD-RENOWNED KNIFEMAKER KEN ONION. IT HAS A VARIETY OF DIFFERENT BELTS FOR GRIT PROGRESSION AND PUTS AN EXCELLENT EDGE ON A BLADE.
ELECTRIC SHARPENERS
Electric sharpeners encompass a wide variety of devices designed to sharpen a blade. They can range from high-quality, effective sharpeners to something that will destroy the edge on your blade. You often get what you pay for, so do your research before buying one.
V SHARPENER
These sharpening tools have two edges, shaped in a V. A blade can be moved through the V with light pressure to grind the edge. By holding the sharpeners at a specific angle, it creates consistency in every pass that can be hard to obtain using a stone. Unfortunately, it most likely isn’t the exact angle you want. It also won’t compensate for the loss of steel that occurs with use over time and will change the shape of your edge.
CROCK STICK SHARPENER
These sharpeners have a fixed base, with abrasive ceramic rods sticking out that are fixed at an angle. The knife is sharpened by running your knife against the rod. Although they are designed to hold a consistent angle, they can be difficult to use, depending on the specific grind on your knife. I find they can work to touch up an edge but don’t work well to redo an edge on a knife that is very dull.
BELT GRINDER
The same grinder that you used to make your grinds can be used to sharpen your edge. The knife is held gently at the appropriate angle against the slack part of a fine belt. This takes a good eye and a steady hand and can be difficult for a beginner due to the speed of which the metal is removed. Grinding in this manner tends to create a slightly convex grind.
BUFFER
A buffer is a machine with a soft, rotating wheel that can be used on both your handle and your blade. By using different wheels and compounds, you can control the level of abrasiveness to get your desired finish. Using this to finish your edge can create fantastic results. It’s important to use extreme care if you decide to buff your knife. I use a large shop buffer when I’m making jewelry and have learned firsthand why the buffer is beyond a doubt the most dangerous tool in the shop. The slightest edge can catch, grabbing and flinging what you’re grinding with incredible speed and force. It’s bad enough to shoot a small dog tag across the room, but that’s nothing when you think about the potential consequences of rocketing a wickedly sharpened knife. If you choose to use a buffer, practice with something that is less likely to kill you first.
MECHANICS OF SHARPENING
The thinness of an edge makes it the most vulnerable part of your knife. This is also the part of the blade that takes the most beating. Every knife will require edge maintenance eventually, as even the best steel will wear with time. The basic mechanics of sharpening will remain the same, whether it’s your blade’s first edge or its hundredth.
Some grinds do best with a small, secondary bevel on the very edge. Other grinds, such as the Scandi grind, are sharpened by refining the original grind. This makes the Scandi grind a very easy grind to sharpen for a beginner, as the angle needed is easy to determine. Depending on the design of your blade and the thickness of your steel, the exact angles you are creating will differ. The edge geometry you used in selecting and creating your grind apply for sharpening as well—just on a finer scale. The first step in grinding is to have a clear picture of the results you are looking for.
Make sure you have good lighting before you start the sharpening process. As with grinding, your sharpening process involves starting with a coarse grit and slowly moving down to finer and finer grits. You’ll have to be able to see when you’ve removed your lines from the previous grit, which can be difficult when you’re working on such a small scale.
If you are putting a new edge on your blade after use, you’ll have to scrape away the worn, damaged old steel on the edge first. This will expose the fresh, strong new steel underneath. You’ll then make a new edge using this steel. Inspect the blade and see what you’re working with. Use a magnifying glass if you are having a hard time seeing the edge. Look for any small chips and assess any visible damage.
IF YOUR BLADE HAS SMALL CHIPS, YOU’LL HAVE TO GRIND THE EDGE ALL THE WAY DOWN WITH A COARSE GRIT UNTIL THEY’RE GONE. RETURNING TO THE BELT GRINDER MIGHT BE THE BEST OPTION FOR SEVERE CHIPS OR BROKEN BLADE TIPS.
When sharpening, the key is to match the angle of the knife’s edge to the sharpener. By keeping this angle consistent and moving your edge across finer and finer grits, you’ll remove all the metal that won’t make up the edge of your blade. The mechanics behind sharpening aren’t difficult to understand, but good results take a skilled hand and a fine attention to detail.
The most important part of sharpening is consistency. If every sharpening stroke you take is at a different angle, you can actually dull your knife. A sharp blade has clean, symmetrical angles. Freehand sharpening takes practice and patience. Use slow, steady hands and take your time. Choose a method and routine for sharpening and stick to it. Repeating your process over and over will commit it to muscle memory and make it second nature.
The level of grit you use to finish your edge is entirely up to you. Grinding creates a scratch pattern, and when sharpening, your edge will have tiny micro-serrations. The coarser the grit of your final grind, the bigger these micro-serrations will be. While the size of these serrations becomes important if you are making high-end specialty knives, the average user won’t notice much, if any, difference on this level.
SHARPENING A BLADE
While using a belt grinder to sharpen your blade is a great method, it also requires actually having the grinder available anytime you need to put a new edge on your blade. As someone who travels frequently and is often away from electricity, I don’t always have this luxury. Learning to use a stone is a worthwhile time investment that will give you the freedom to maintain your blade anywhere.
One useful technique to use when you’re learning to sharpen is to use a marker to color the edge of the blade. Much like marking the steel during the grinding process, this will allow you to see where you are removing metal and where the metal isn’t coming in contact with the sharpener. It will also allow you to see the angle at which you’re grinding.
A strop will be used to make the final touches on your edge. Stropping will remove the last of the burr and clean and align your blade’s micro-serrations. You can buy a strop specifically made for this purpose, or you can use an old belt, a piece of denim, or even cardboard in a pinch.
MATERIALS AND EQUIPMENT
knife
sharpening stone
strop
1. GRIND THE FIRST BEVEL OF YOUR EDGE.
Hold your knife flat on its side on your coarse stone. Lift the spine up slightly so that the edge is resting on the stone at a sharp angle. Move the edge across the stone lightly, as if you were trying to slice off a very thin piece of it. Make sure the entire length of the blade, from the heel to the tip, comes in contact with the stone. Repeat this process several times, maintaining the same angle.
USE A MARKER TO HELP PERFECT THE ANGLE THAT YOU’RE HOLDING THE BLADE AT IN RELATION TO THE STONE AND CHECK TO SEE WHERE YOU HAVE REMOVED YOUR MARKS. AN ANGLE THAT IS TOO STEEP WILL ONLY GET RID OF THE MARKER ON THE VERY EDGE WHERE THE BEVELS MEET. AN ANGLE THAT IS TOO FLAT WILL REMOVE YOUR MARKER FROM THE SIDE OF YOUR EDGE, LEAVING THE MARKER CLOSEST TO THE EDGE.
2. CHECK FOR THE BURR.
As you remove steel from the edge, a tiny burr will eventually form on the opposite side of the edge. The burr is a rough, raised metal curl that results from grinding metal. The burr should appear evenly along the entire length of the edge. If you find that it is absent in an area on your edge, you aren’t grinding as much on that particular spot.
3. SWITCH SIDES AND REPEAT THE PROCESS WITH A FINER GRIT.
Once you have a burr along the entire edge, switch sides. Repeat the process until you have a burr on the second side. If you have any chips in your blade, you’ll have to continue grinding with a coarse stone until all the steel is removed past that chip. Once you have set your edge with the coarse stone, move to a finer grit stone and repeat entire the process again.
BRING THE EDGE OF THE BLADE ACROSS THE SHARPENER LIGHTLY. LET THE STONE DO THE WORK INSTEAD OF TRYING TO MUSCLE THROUGH IT.
4. STROP YOUR EDGE.
Use your strop to remove the final burr on the blade’s edge. Stropping involves the same motion that is used while sharpening on a stone, but in reverse. Instead of cutting forward, the blade is drawn back, dragging the edge on the strop. Use light pressure and make several passes, alternating sides.
THE BURR MIGHT BE VISIBLE, BUT YOU CAN ALSO TEST FOR IT BY USING YOUR FINGERNAIL. SCRATCH THE EDGE OF YOUR BLADE GENTLY, FROM THE SPINE TO THE EDGE. IF YOUR NAIL CATCHES SLIGHTLY, YOU HAVE A BURR.
5. TEST YOUR EDGE.
There are many ways to test your edge to see if it is sharp enough. Everyone has their own favorite method, from seeing how well the blade cuts through paper to carefully drawing the edge along a fingernail. In my opinion, the best way to see if an edge is sharp enough is to try using it for its intended purpose. A properly sharpened knife will complete the task it’s designed for with ease, so see how well it performs in the field. As you become more familiar with your particular blade, you’ll be able to tell when it starts to lose its edge.
STROPPING HELPS TO ALIGN THE BLADE’S EDGE AND CAN BE USED TO MAINTAIN YOUR BLADE BETWEEN SHARPENINGS.
SKINNING BARK FROM A TREE WITH A BUSHCRAFT KNIFE. USING THE BLADE FOR ITS INTENDED PURPOSE AND SEEING HOW WELL IT FUNCTIONS IS A GREAT WAY TO DETERMINE IF ITS EDGE IS ADEQUATE.
KEEPING AN EDGE
Knifemakers are at an advantage when it comes to knowing how to take care of a blade. Now that you know what it takes to make an edge, it’s easier to imagine and avoid the processes that what will ruin one. If you’re in a survival situation, it’s incredibly important to protect the item that you are using to keep you alive. Even if you’re not, it can be devastating to ruin something you’ve invested so much time into.
My number one pet peeve with knives is people who carelessly stab their knife into the dirt when working outside. Even if they don’t stab it on a rock and chip the edge, soil is an abrasive. The edge of a blade is created with abrasives; it can also be destroyed by abrasives. Keep your knife in its sheath when you’re not using it. This protects your blade from any unnecessary damage, as well as protecting you from accidentally cutting yourself.
Avoid cutting on any cutting surface that is harder than your blade’s edge. Another common practice I see is using a rock as a cutting surface. Your blade will thank you if you use a log or piece of wood instead. Cutting boards not only serve as a surface to cut on but are important to protect the integrity of the knife.
It’s tempting to use your blade as an all-purpose tool, but take it from someone who learned it the hard way; your knife is not a pry bar or a screwdriver. You might get away with it for a while, but if you make it a habit, your blade will probably take damage at some point.
Make sure to dry your blade when it gets wet and rinse it if it comes into contact with saltwater. Don’t store your blade for long periods of time in the sheath, as the leather can collect moisture and cause corrosion. All carbon steel will need care to prevent corrosion in the form of surface rust, so anything you can do to be proactive is a help. If you do see rust forming, use fine grit paper to remove it as soon as possible and apply a light coat of oil. I also recommend oiling your blade every so often, especially if it will be sitting unused for a period of time.