Guide to Sharpening

Have you ever heard “A sharp knife is a safe knife”? I don’t know that to be entirely true, I’ve seen some real reckless folks wielding sharp knives, but for most of us, this statement bears true. A dull knife will drag and tug as you cut causing you to vary the pressure you’re putting on the blade. At the most inopportune moment the blade may break free and rapidly and in a less controlled manner, continue cutting through your material and possibly beyond! Late last year I had an occasion to be enjoying my morning Starbuck when an accident occurred. I like to enlarge the vent hole because the manufacturing process they use leaves a “hanging chad” to turn a phrase that partially blocks the airflow. I typically use a pen to enlarge this small hole to let my morning caffeine flow smoother, but on this particular morning I didn’t have a pen handy, but I did have my handy pocket knife. After retrieving it and deploying the blade one-handedly I began to try to poke through the lid. It gave some resistance so I pushed harder. Abruptly it broke through and sliced clean across my opposing thumb. The slice wasn’t bad, didn’t need stitches and I only wore a bandage through the day, however, it was a painful reminder that a properly sharpened edge is much safer.  Being proficient in sharpening your knife is a required skill for self-sufficiency and safety.

How Often?

The first rule of maintaining the edge on a knife is to remember that with normal use, a pocket knife will need to be really sharpened only a few times per year. It’s important to understand the how a blade is sharpened, as well as how the edge is maintained between sharpening. You’ll be maintaining the edge with a honing steel or strop much more than you will actually sharpen it with a stone or file.

Tools Needed:

For the periodic deep sharpening, a sharpening stone is required. You may have heard this called a whetstone, an Arkansas stone, etc. If the blade is extremely dull and abused you may need to use a metal file to work the blade back into a basic shape. You will need coarse grit and fine grit sharpening stones. For most work, a two-sided stone with a coarse side and a fine side will do the trick. For more advanced sharpening, progressive levels of fine-ness may be advisable.

Another basic item required is a honing steel. This is the cylindrical tool you’ve probably seen chefs on television using before they begin chopping. A honing steel can be found anywhere that sells quality whetstones. Think of hardware stores, kitchen supplies stores or specialty knife shops.

Another recommended item is a leather strop. You’ve probably seen barbers (mostly on television these days) run their razor over their leather strop before starting a shave – I’ll explain why a little further on.

These tools are not prohibitively expensive.  The Smith’s Arkansas Tri-Hone above has 3 grades of stone and retails for about $20. The top-of-the-line Henckel’s Sharpening Steel is less than $20 and the hanging leather strop pictured above can be had for about $8. Finally, a lubricant such as 3-in-one oil, mineral oil or a specialty sharpening oil can be used to lubricate the whetstone.

the Sharpening process

Sharpening a knife correctly starts with understanding the geometry of an edge. Folding pocket knives used for every day carry (EDC) have a blade thicker than a kitchen knife and should have a primary and a secondary edge.

For a dual-angle edge, start with a coarse-grit stone. The primary angle should be about 22 degrees. It’s safest to set the stone on a firm surface and work the blade along its length. To position the blade properly lay the blade flat on the stone facing away from you. Now raise the back edge of the blade until it forms an approximate 22 degree angle with the cutting edge still touching the stone. Angle guides can be purchased, but there’s a simple and quick trick to make one from a simple square of paper. Make sure the piece is truly square, then fold one of the 90-degree corners in half, leaving a 45 degree angle. Fold in half again to create a 22.5-degree angle. This can serve as a simple visual guide to match the angle of the blade to the sharpening stone.

Primary Angle
Initially you will want to prep the stone by putting a couple of drops of oil directly on the stone. Next, slide the blade along the stone maintaining the 22-degree angle. After a few passes turn the blade over and make the same number of passes to make sure you’re removing the same amount of material, microscopic though it may be, from each side.  Repeat the process on each side several times, always maintaining the proper angle to the stone. Now stop and look at the cutting edge closely under a bright light – you will see flats and valleys, dull spots and bright spots that should begin to even out as you make progress sharpening along the entire length of the blade. You’ll want to repeat this process on each of the grades of whetstone you have, going from coarse to fine. 

Secondary Angle
For the secondary angle, you’ll need to maintain about 10 to 12 degrees between the blade and the whetstone. To visualize this angle, fold your 22.5 degree paper guide along it’s center to form an 11.25 degree angle reference. The secondary angle is honed with the finest surface of the sharpening stone. You will make several passes on each side of the blade with much lighter pressure than the primary angle. The key is to make sure you’re maintaining full contact with the blade along its entire length from hilt to tip.

Honing Steel
The next step is insuring the newly sharpened edge is completely straight. In addition to being the next step in putting a fine edge on a blade, this is also a great for maintaining the relative sharpness of the blade and can be done throughout the year as a touch-up. Most knives are not dulled because the sharp edge is blunted but because the leading edge has curled over. A finely honed edge is prone to bending under even a light pressure. That’s why a barber runs his straight razor across a strop several times each day and a chef hones his knife on a honing steel.

To start, hold the honing steel vertical with its tip against a chopping block or other softer horizontal surface, place the blade on one side of the steel rod near the handle with the blade at about 11-degrees – just like before. Make a swipe down the rod drawing the knife toward you as you go so that the tip is honed before the blade reaches the bottom of the rod. The movement is as if you are trying to slice a very thin piece off the rod, making sure to use the entire length of the blade. Now switch the blade to the opposite side of the rod and repeat. You can do this process several times alternating sides with each pass while maintaining the proper angle. Doing so will straighten any microscopic curls along the edge of the blade.  The last step in the process is what takes the edge to its final razor sharpness.

Stropping
The leather strop puts the final straightening on the blade edge. It may be preferable to use a stropping compound to enhance its effectiveness – something such as jeweler’s rouge works well. Stropping is done by drawing the blade down the piece of leather, blade spine first with a light to medium pressure and about a 5 degree angle. Make a pass, then lift the blade from the leather and flip it over before and make a pass on the opposite side of the cutting edge. Always lift the blade completely from the strop before rotating it to the opposite side at the end of a pass.

Conclusion

Following the stropping I recommend taking a moment to put a light oil on the blade and lubricate the pivot points as well as checking for loose fittings or screws. This is preventative maintenance so it’s worth taking the time to remove the clip, if any, and thoroughly clean the knife all over. This way, it will always serve you well when needed.