There’s an old saying, “The two most useless and dangerous things in the world are an empty gun and a dull knife.” If you carry and use a knife on a daily basis, you may notice it getting dull. This is especially true if you cut a lot of cardboard, rope, or carpet. Some materials seem to eat blade steels worse than others.
What gives a knife its sharpness are microscopic “teeth” known as carbides. You cannot see them with the naked eye, but when looked at under a microscope of sufficient power, your knife edge will have millions of jagged edges resembling diamonds or teeth. These are known as carbides and refer to the presence of carbon in the blade. As you can imagine, carbon steel will have more than stainless steel as a rule.
The act of sharpening your knife blade exposes these carbides and what actually makes the knife sharp. Depending on what type of abrasive material that you use to sharpen your knife will determine how coarse or fine these teeth become. Coarser cut carbides are great for cutting into fibrous materials such as rope, whereas more finely polished carbides are better for softer materials.
Methods of Sharpening Your Knife
The sharpening stone is the oldest and probably the most basic way to sharpen a knife. We often see Arkansas Whetstones packaged with some field knives in a pouch on the sheath. Although the cheapest or most easily accessible, they can be a bit challenging for new users, especially when trying to set the correct sharpening angle of the blade. Typically, a honing oil is used to aid in the process. This is a mineral oil that will protect the stone from debris removed from the blade.
BladeOps offers a man-made set of sharpening stones fromMikarto Knife Ware as a dual grit 400/1000 whetstone. This gives the user rough grit and fine grit to aid in blade maintenance.
Spikes or Rods
Similar to the sharpening stone are what are often known as spikes, rods, or sticks which are usually made of ceramic. Sometimes these are called diamond rods and some are made with heavy-duty material such as tungsten carbide. They are available as a single unit but can also be had in sets of two that come with a mounting base in order to maintain the geometry of the edge of the knife’s blade by giving a correct sharpening guide to the blade. Spyderco’s Sharp Maker has been the industry standard on rods such as these for decades.
In recent years, manufacturers of knives as well as sharpening systems have been offering small, portable pull-through type sharpening tools using this same principle. Smith’s has their famousTwo Step Knife Sharpener which uses a carbide set of rods and a ceramic rod. You use the carbide for a coarse edge and the ceramic for more of a fine edge or to touch up your coarse edge when finished.
A steel sharpener or honing rod is a further evolution of the basic stone. Only, as the name implies, you use a piece of steel to sharpen your knife.
When buying kitchen knives, it is not uncommon to find a Butcher’s steel packed with the knives. If you have never seen one used in real life, please dispel what you may have seen in a movie or cartoon with someone wily-nily rubbing their knife maniacally against the rod.
Rather, Butcher Steel is used on carving and boning knives to smooth out any nicks or dents caused by hacking through a large bone or something else. It is not a sharpening system. Likewise, these tools are primarily intended for use only with the set for which they were made or knives of similar steel. You can end up damaging your pocketknife with a Butcher Steel intended for a set of Henckel’s knives.
BladeOps carries a product from Spyderco that may revolutionize the use of steel in sharpening with theWebfoot Stone Sharpener. This completely unique approach to sharpening doesn't require oil, water, electricity, or any other complicated fixture or addition. It can be set up in seconds and is made of carbon steel with a coating in Cubic Boron Nitride. It is easy to align this sharpener at a consistent angle. A 40-degree angle for utility knife edges, 30 degrees for keener, thinner, high-performance knives, and even 12.5 degrees for scissors and shears. The Webfoot can quickly and easily sharpen an assortment of tools, including those with serrated edges.
<h3> Belt Sanders
For a fast, efficient, and accurate way to sharpen a knife, there is always the belt sander. You may have one in your home workshop.
You will need a good variety of belts in order to do this correctly. First, you will want to start with a coarse belt like 150-grit. Keep the sharp edge pointed downward at the correct angle of the grind and make a few passes with one side. Remember to count how many times you do this. Then, grind the other side for the same number of passes. Change the belt to a 240-grit belt and repeat. You will want to continue doing this with belts in 400-grit and down to a 9-micron bit. Finally, you will want to finish with a leather belt or razor strop using a polishing compound.
Remember, it is a mechanical piece of equipment and can be less forgiving than a manual sharpener. It is a better alternative to kitchen sharpeners that ar often incorporated into electrical can openers. If you truly care about your blades, do not use one of those.
A leather strop can come in handy to polish and smooth the final edge on a blade. These were popular with barbers who used them on straight razors for centuries. In this case the abrasive property of the leather cleans up small amounts of residue from the carbides. You can buy a professional strop or simply use the rough inside of a leather belt. Knifemakers such as Ernest Emerson recommend stropping against material such as denim or even the cardboard back of a legal pad.
Steps to Sharpening Your Knife with a BladeOps System
Regardless of which sharpening system you use, you will find it most often comes down to personal preference when sharpening a blade. Some prefer belt sanders; others prefer sticks and old-school types swear by the stones. Either way, it is important to follow a safe and effective sharpening process.
Always start by cleaning the blade first and inspecting for nicks, gouges, or chips. Keep your work area well-lit. Check your blades for the correct angles and be careful. If you are sharpening a selection of different knives be mindful that based on their intent that the knife may have a different angle than the others.
Why Is a Dull Knife Dangerous?
A dull knife can be extremely dangerous to you or to others. When a knife is showing signs of losing its sharpness, instead of looking for another one to complete the job, many users will simply use more force than normal to complete the cutting task. This excess force can cause the user to lose control of the knife and can lead to a bad cut on themselves or someone standing nearby.
If the blade won’t slice through a loose piece of paper or a block of cheese, it probably needs to be sharpened or at least touched up. There are other ways to test your knife’s sharpness as we will see next.
How Do You Know When to Sharpen Your Pocket Knife?
There are three basic ways that you can check the sharpness of any knife.
The first is a visual Inspection of the edge of the blade. You can literally see if it is sharp or dull. You start by holding the knife perfectly straight and while looking at the edge, slowly tilt it from side to side. You want to see if light is reflecting from the edge as it will indicate that the blade is dull because the edge will be pulled to the side. You can also spot any nicks or chips in the blade. Remember, if you don’t see reflected light across the blade, you are good to go.
Secondly is the fingernail test. Because of different sharpening techniques and some blade coatings, the visual test can be a little hard to go by 100% of the time. At knife shows like the Blade Show, you may see people shaving their arm hair with a knife. While accurate, it can be a bit unseemly. We recommend the fingernail test, instead. You take your knife and very lightly tap the edge on your thumbnail. If the blade digs in like an axe blade into a stump, your knife is sharp. If it bounces or slides off then your blade is dull.
Lastly, is the kitchen test. This may have started with the Ginsu Knife commercials in the 1970s, but it has been observed on cooking shows countlessly over the past 4 decades. It uses either a tomato or fresh herbs because these are some of the more fragile ingredients at a chef’s disposal and experienced chefs regularly use them to test the sharpness of their knives.
When using the tomato, the knife should slice cleanly with no effort and minimal pressure. If you cannot break the skin of the tomato or if the cut is ragged looking, you need to touch up your blade. If you use fresh herbs like thyme or parsley, the cut should be clean, and you should observe no bruising or mashed ends on the cut herbs.
This article is reviewed by Trevor Darby, MBA, MBC.
Trevor Darby is a book author and freelance writer as well as owner-operator of a leading knife shop in the United States for the past fifteen years. He has designed several knives and is an authority in the field of specialty knives in the US.
Raised in Hollister, CA, he now lives in South Jordan, UT with his wife and two of their six children. He spends his spare time whittling and writing.