Why Sharpen a Knife (and a Bit about How)

Dr. Ryan Hanning​

Certain tools possess primordial qualities. The simpler the tool the more visceral response it yields. When I give my son a hammer, an ax, or a saw it is as if the entire woods demand to become a cabin. They no longer see thick trunks and hanging boughs; they see posts and beams. Somehow, this creative impulse written into our DNA is triggered by the handling and use of these tools. This could be simple nostalgia. There is something beautiful about using the same human ingenuity in the very same way as did our ancestors in to the stone age. I would like to think that something deeper than nostalgia is happening. It is only natural that the creative impulse of the imago dei is animated by the use of tools. Afterall, our yearning to create is simultaneously met with an awareness of our finite limitations. We are not all powerful and cannot create without tools. We depend on them to fulfill our call to “cultivate and till” the earth. I propose that these tools speak deeply and immediately to our participative relationship with nature.

Perhaps this is why moral and ethical constructs guide our use of tools. Using a tool well and for its intended purpose to achieve its intended outcome is “good.” As in, “hey son, good job using that hammer to fasten the fence board to the post.” Versus, “hey son, bad job using that hammer to break Mom’s flowerpot.” We even project these moral values onto the tools themselves. We honor their excellence when they work well and curse their deficiency when they fail. We assign personal agency to them and give them names. Anyone who works in a trade knows that a tradesman’s preferred tools have a type of primordial kinship with him. King Arthur’s Excalibur, Thor’s Mjölnir, Bilbo Baggin’s Sting, Ryan’s Linemans’. My boys know that if they lose the pliers I have had since I was 15, they take on a mythical, bordering superstitious, power to doom our current electrical project. All this to say, we want our tools to work well, and to help us achieve the outcomes that they were designed for. This requires respect, proper use and proper maintenance.

Knives hold a pride of place in the hierarchy of tools. Historically they demonstrate early man’s mastery over cleaving rocks to hone an edge, and later the ability to forge metal into a myriad of combinations. Knives take on a cultural significance as well. I remember getting my first knife and the accompanying lecture of proper use, control, self-possession, and responsibility. This lesson has not been lost on my own children. In many ways, knives are the ultimate tool and the ultimate illustration of mankind’s use of technology to subdue and participate with nature.

How to sharpen a knife?

There are lots of ways to sharpen a knife and equally worthy debates over proper sharpening techniques for specific blade designs and metals. Here we review the basics of getting an edge worthy of giving your knife a name and assigning it mythical powers.
Sharpening vs. honing: Sharpening removes material from the edge of the knife and sets the blade angle. Refining it to a narrower point thus making it sharper. Setting the angle on the blade edge determines both its sharpness and durability. 25° is ideal for hunting and pocketknives, 20° is great for kitchen cutlery, and 17° is the norm on expensive paring and fillet knives. Honing a knife does not remove material as much as it brings the edge back to center and removes small imperfections to keep it sharp along the whole edge.

There are lots of sharpeners on the market. Pull through models which have two overlapping wheels or rods in a “v” pattern of varying “grit.” And whetstones (“whet” is old English for “sharpen”) flat abrasive pads of varying designs and grit. Both are effective, as are a variety of electric belt and wheel sharpeners. In my experience to put an initial edge on a knife or repair a blunted edge, the whetstone is the way to go. For general maintenance and keeping an edge a pull through sharpener works great.

Using pull through sharpeners:

These easy to use sharpeners typically have at least two different “grits”. A coarse one for roughing out the edge, and a smooth one for honing the edge.

Step 1: Gently place the heel of the knife blade (the part closest to the handle) in the coarse grit notch and smoothly pull back in one motion allowing the edge to glide through the sharpener from the heel to the tip. Repeat this several times with light pressure until the blade glides through with little resistance.

Step 2: Gently place the heel of the knife blade in the smoother grit notch and smoothly pull back in one motion allowing the edge to glide through the sharpener from the heel to the tip. Repeat this several times with gentle to no pressure until the blade glides through without resistance.

Step 3: Thoroughly clean the knife as fine bits of metal dust will be on the blade.

Step 4: Evaluate the sharpness of the blade. There are many ways to test the sharpness of the blade. Of course there is the traditional shave test which sacrifices some arm hair, as well as sliding the blade across your thumbnail to see if it sticks. These are tested but dangerous ways to evaluate the blade and are not recommended. It is far better to cut something that the knife would ordinarily be used for and evaluate its performance.

Using whetstones:

These sharpeners take a little more time to master but come in varying designs to make it easier on the user. They all use the basic principle of using rougher to smoother grits of abrasive to create, refine and polish an edge on a knife. Traditional whetstones are flat stones of varying grit but can include any form of sharpening stone including those made from ceramic or diamond. Most whetstones will lay flat and you move the knife across the surface. Other designs hold the knife stationary and the stone is moved across the blade. Some whetstones use water, others use oil, so be sure to read the manufacturer’s recommendations.

Step 1: Evaluate your knife and set up the appropriate starting stone and angle. 70 grit can be used for re-profiling damaged or severely dull knives. 120-300 grit are generally a good starting point. Some kits use only one stone with two sides, others will have multiple stones.

Step 2: Wet your whetstone. Follow the manufacturer’s instructions. Some stones are soaked in water for 10-15 minutes, others are sprayed with water, or lightly coated in oil.

Step 3: Select the angle you want for your blade. Some sharpening kits have tools to ensure that you keep the correct angle, others will rely on your steady hand.

Step 4a: If using a traditional flat whetstone place the knife on the stone at the appropriate blade angle and slice forward with constant and even pressure, moving the knife in an arc from heel to tip. Make a smooth sweeping arc covering the entire stone. Repeat this multiple times alternating sides of the knife each time. A thin layer of mud might gather on top. Leave it, that slurry helps lubricate the blade.

Step 4b: If using a sharpening kit that moves the stone over the blade, the same principles apply as above. Move the stone from the heel to the tip in a sweeping arch that is pulling towards the blade.

Step 5: Repeat these steps with finer grit stones, cleaning the blade each time, until your honing stone finishes the edge.

Step 6: Thoroughly clean the knife as fine bits of metal dust will be on the blade.

Step 7: Evaluate the sharpness of the blade.

Tips:

Keep your knife sharp. The adage that a “dull knife is more dangerous than a sharp one,” is true. With the acknowledged exception of knife fights, which we generally refrain from. Dull knives lead to slippage and over exertion which cause accidents.

Sharp is sharp enough. Do not over sharpen. A razor edge is not necessary for most applications, and on most knives, it will lead to premature dulling.

Use the right knife for the right job. Have reasonable expectations for your knife, and learn the value of different builds, designs, and blade materials.

Make your knife an heirloom. A knife can last for generations. Keep it clean, well sharpened, and oiled, as necessary. One of my prized possessions is a small knife that my father gifted to me along with a wild yarn about its origins from a South African diamond mine. After his passing, one of his close friends confirmed the story. I will proudly pass it on to my oldest son, along with a few additional tales of my own.

Make knife giving a rite of passage: Giving your son or daughter a knife is a sign of trust and a call to responsibility. Do not miss out on the moment. My children expect that our camping trips in or around their 8th or 9th birthday result in a fireside gift giving ceremony. One that includes giving them a knife, teaching them to use it, and expressing my pride and trust in their ability to use it wisely. They also get the warning that using it poorly will result in consequences including losing the knife, which is far better than losing a finger. My older children participate in the gift giving and affirm the readiness of their brother and sister and also pledge to help them learn to use this tool for its intended purposes and to advance their good and the good of the family.

Note: Before you send letters to the editor (which is always encouraged) I recommend sharpening towards the blade (as if the blade is cutting the sharpener) because it folds the burr under as opposed to building the burr on the opposite edge. Others would disagree. But they are wrong and possibly ill-intended. (Just kidding.) There are pros and cons of both ways and even a popular middle ground saying that you should rub the knife back and forth. Either way, practice will make perfect and over time you will likely develop your own regimen to keep your knives in top shape.

Photo by H&F photographer McKenna Runde.

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