Sharpen a Knife

Purchase a whetstone or diamond stone. Decide on an angle to sharpen your knife - it could be the current angle or a 17° - 20° angle. Apply a small amount of honing oil to your whetstone. Place a sharpening guide underneath the knife and use it to guide your movements. Drag the knife across the rough grit side of the stone repeatedly until you raise a burr. Flip your knife and sharpen the other side of the blade in the same way. Flip the stone over and sharpen each side of the blade to eliminate the burrs. Alternate your swipes by switching the side of the knife you're sharpening. You can also use a honing rod or an old coffee mug to sharpen your knife.

Steps

Using a Whetstone or a Diamond Stone

  1. Pick an angle to sharpen your knife. If you already know what angle your knife is sharpened at, you'll probably wish to sharpen it at this angle again. Sharpening at a different angle will take significantly more time and may take a few goes before any rough angles are smoothed out.
    • If you don't know the current angle, ask the manufacturer of your knife or inquire at a knowledgeable knife shop to determine what angle is appropriate for your knife.
    • If you have to make a gut decision, choose an angle of 10° - 30° per side. Shallower angles make a sharper edge that doesn't last as long; steeper angles are more durable, so 17° - 20° is a good compromise between the two.
  2. Lubricate your whetstone or diamond stone with a small amount of mineral oil. Look for honing oil, a light kind of mineral oil. Honing oil will both lubricate the whetstone, making it easier for the blade of the knife to pass over the stone, as well as keep the steel shavings (the by-product of sharpening) from clogging the stone's pores.[1]
    • Check with the manufacturer's guidelines for your stone regarding lubrication. The most common sharpening stones are carborundum stones, and are designed to be used wet or dry, but are destroyed when oiled. However, there are some stones that are specifically designed for oil, and will generally be labeled as "oil stones".
  3. Use an angle guide to control your edge's angle, if available. A sharpening guide is a small tool that's placed underneath the knife in order to maintain a constant angle when scraping the knife across the surface of the stone.[2] Otherwise, you will have to control the angle by hand, which is hard and requires a well-formed perception of angles.
    • One of the most difficult aspects of sharpening a knife is getting the angle right. To make this process a bit easier, try painting the very tip of both sides of your blade with a sharpie pen. Then, throughout the sharpening, inspect whether the marker is being removed during the process.[3]
  4. Start off on the rough grit side of the stone. Check the grit on your stone, or the packaging that came with the stone, to identify which is which. In general, whetstones and diamond stones each have different grits on either side. The rough grit side is used to grind the steel down, while the fine grit side is used to sharpen or hone the knife. The grinding process comes first, so you start on the rough grit side.
  5. For a symmetrical edge, sharpen the knife by dragging it across the stone in the opposite direction you would move it to slice a thin layer off the stone. This allows a burr to form and prolongs the stone's life.
  6. Continue grinding at this angle until your grind goes roughly halfway through the steel. This doesn't need to be precise, just well-estimated. For a one-sided edge ("scandi grind", "chisel grind", etc.), do not flip the knife when instructed to do so by this article.
  7. Flip the knife over and sharpen the other side of the blade until you create a new edge. The easiest way to determine that you have removed enough metal is to sharpen until you have raised a burr, a feature that steel will naturally form when one bevel is ground until it meets another.
    • Burrs will generally be too small to see, but you can feel it scraping/catching on your thumb if you stroke away (dull side of the knife to the sharp) from the edge. Finer stones produce smaller burrs, but they are still there.
  8. Flip the stone over and begin sharpening one side the blade, this time using the finer grit. Your goal here is to smooth over and eliminate the burrs created by sharpening the knife over the coarser grit. This transforms the blade edge from a ground edge into a finer, honed edge.
  9. Flip the knife and begin sharpening the one side of the knife on the fine grit side of the stone. Again, make sure you hit both sides of the knife with the fine grit.
  10. Begin alternating swipes on the fine grit. Sharpen one side of the knife with a single stroke, then immediately flip the knife and sharpen the other side. Do this several times for the best result.
  11. If you wish, further polish or even strop the edge to the desired sharpness. This makes the edge better suited for "push cutting" (cutting directly into materials, pushing straight down without sliding the blade across the object) but generally impairs slicing ability: without the "microscopic serrations" left by grinding with a stone, the blade tends to not bite into things like tomato skins.

Using a Honing Rod (Sharpening Steel)

  1. Use a honing rod in between sharpenings to keep your blade from degrading. The honing rod, or simply "steel" as they're often called, aren't normally used to resuscitate a dull blade from the proverbial graveyard. Instead, they're often used to keep knives sharp in between use.
    • Using a honing rod regularly delays the need to use a whetstone or a diamond. This is a good thing: Using whetstones and diamonds shave metal from the edge of your blade, reducing the knife's lifespan. The less you use your whetstone, the longer your knives will thrive.
    • What does a honing rod do? A honing rod realigns the metal in a blade, massaging small nicks, indentations, and flat spots away. Compared to a whetstone, it does not remove any significant amount of metal from the blade of the knife.
  2. Hold the honing rod in your non-dominant hand. The rod should be held at a comfortable angle facing away from your body. The rod tip should be elevated above the rod handle.
  3. Hold the knife firmly in your dominant hand. Your four fingers should be holding onto the handle, while your thumb can be placed on the spine of the knife, far away from the blade edge.
  4. Hold your knife at approximately 20° in relation to the honing rod. Your angle doesn't need to be exact, just approximate. Whatever angle you decide to choose, or unwittingly end up choosing, make sure to maintain the same angle throughout the honing process. Changing the angle used during the honing process won't smooth out the metal in the blade as much as using a consistent angle will.[4]
  5. Maintaining a 20° angle, move the knife across the top half of the honing rod. Try to start this motion with the heel of the knife touching the rod and end it with the tip of the knife touching the rod.
    • In order to master this process, you'll need to move your arm, your hand, and your wrist. What's especially important to get the right action is moving the wrist. Without moving the wrist, you won't be able to sweep the entire blade — heel to tip — across the honing rod.
  6. Maintaining a 20° angle, move the knife across the bottom half of the honing rod. Using the same sweep of your arm, hand, and wrist, gently move the knife across the lower half of the rod. Use only as much pressure as the weight of the knife itself. After completing both a top- and bottom sweep, you've done one revolution.
  7. Do a total of 6 - 8 revolutions with your honing rod before each use of the knife.

Using a Coffee Mug for Quick Results

  1. Place an old coffee mug upside down so that the bottom of the mug is exposed to the air. In a pinch, a coffee mug can serve as a surprisingly effective sharpening tool if you don't have any fancy equipment. The ceramic material of a mug is a coarse-enough material to get good results. Indeed, some honing rods even use ceramic material to keep a blade homed in between sharpenings.
  2. Maintaining a 20° angle, sweep one side of the blade across the grit of the coffee mug several times.
  3. Maintaining a 20° angle, repeat the process using the other side of the knife.
  4. Alternate sides of the blade for the final two or three sweeps. Take one side of the blade and run it across the coffee mug, then turn the blade around and hit the opposite side. Repeat this pattern several times.
  5. Finish the process with 6 - 8 swipes of your blade across a honing rod. Smooth out any burrs or kinks in the metal with several swipes on your trusty honing rod.



Tips

  • Electrically powered stones and grinding wheels need to be used with great care. Heat generated by the stone while grinding with these devices can anneal (soften) the steel, causing the knife to dull quickly with use.
  • Some experts recommend sharpening as if trying to slice a thin layer or decal off the stone. Don't consider doing this without significant experience: it is typically bad advice; most people don't hold the correct angle this way. You instinctively raise the blade until you feel and see the edge working. This creates larger edge angles and thicker bevels as time goes on and the results gradually deteriorate. The more you sharpen, the duller it gets. Sound familiar?
  • Cheaper stainless steel kitchen knives won't hold an edge well; don't get discouraged - it may not be your sharpening technique. They will sharpen just fine, but will dull very quickly. What's happening is that the edge is rolling over because the steel is soft. Try using a steeper sharpening angle or a knife with harder steel.
  • Sharpening stones work best with a lubricant to help keep the stone free of particles. Use either an oilstone with a neutral oil such as mineral oil, or water stones with water. Once you start using a stone with oil, you cannot switch to water.
  • Keep a first aid box near you so that in case of any bad emergency you can do primary treatment before you go to the hospital.

Warnings

  • If you do not remove enough metal to create a new edge, you will leave some of the dull edge in place. A dull blade (or a blade with dull spots or nicks) will reflect light from the very edge of the blade. A razor sharp knife edge will not show "bright spots" when you hold it blade up under a bright light. You will need to remove enough material from the sides of the bevel so that the edge stops reflecting light.
  • Don't drag your fingertip across the newly sharpened edge to see if it is sharp. A better test is to try to cut a single piece of newspaper while holding the paper loosely between two fingers.
  • If you are using an oil stone don't use water on the stone, at it will cause the pores of an oil stone to clog and become useless for sharpening.
  • Always be careful around recently sharpened knives (and all knives in general). Practice correct knife skills to prevent accidents.

Things You'll Need

  • Knife
  • Flat, abrasive surface: Arkansas stone, rock, sandpaper...
  • Angle guide or a steady hand

Related Articles

Sources and Citations

  1. ↑ https://www.danswhetstone.com/information/common-questions/
  2. ↑ http://www.artofmanliness.com/2009/03/05/how-to-sharpen-a-pocket-knife/
  3. ↑ http://lifehacker.com/5903770/the-right-ways-to-sharpen-a-knife
  4. ↑ http://cooking.stackexchange.com/questions/27972/using-a-ceramic-honing-rod-for-global-knives
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