The Right Way(s) To Sharpen A Knife

Keeping your knives sharp isn’t just convenient; it’s safe. Any chef will tell you that dull knives cause accidents. But how to keep your blades sharp without calling in the neighbourhood knife sharpener or taking them into the local butcher (which is a perfectly good place to start, by the way)? The DIY experts at Stack Exchange have your answer(s).

Image: Stack Exchange.


I have a sharpening stone like the one seen to the right, but I’m not certain how to use it. A few questions:

– What is the proper way to sharpen a knife with a stone like this?
– Do I need any other tools?
– Do I need any protective equipment?
– Do I have to use some type of oil?
– Is it better to go fast, or slow?
– Is the procedure different with a knife that has never been sharpened before?
– Do I have to do anything different if the blade has rust on it?
– How do I know when the knife is sharp?

Tester101 (originally asked here)

Answer: The Long Answer(s)

It is very hard to describe knife sharpening via text. I’d recommend searching out a few YouTube videos for tips on technique. That said, here’s my two cents:

What is the proper way to sharpen a knife with a stone like this?
If the knife is already sharp and you’re just touching up, start with one of the fine stones. If not, start with the coarsest. Work your way from coarser to finer. Put some oil on the stone, put the edge of the knife on the stone at the angle you want (try to match the existing angle), then stroke the knife along the stone as if you’re trying to remove a fine shaving of stone. Pull the knife as you do it to sharpen the entire edge.

Do I need any other tools?
No. A jig for keeping the sharpening angle can help, but most likely wouldn’t be usable with a stone like this.

Do I need any protective equipment?
No, but be very wary of where your fingers are, and where the edge can go if you slip. Keep your fingers out of that area.

Do I have to use some type of oil?
With most stones, yes, lubricant must be used to carry away the swarf, or metal particles. Diamond and Japanese-style waterstones should generally be used with water. But with the stone shown above, I would use vegetable oil. Veggie oil can go rancid, but cooking knives are used and washed often enough that this shouldn’t be an issue.

Is it better to go fast, or slow?
Slow. I like to take long strokes along the whole edge, concentrating on keeping my angle consistent. I use about a 20° angle on kitchen knives.

Is the procedure different with a knife that has never been sharpened before?
Only that you would probably start on a coarser stone.

Do I have to do anything different if the blade has rust on it?
Remove the rust first with fine sandpaper.

How do I know when the knife is sharp?
There are many ways to test. There is the old newspaper test, where you hold a piece of newsprint in one hand and cut it with the other. Also, you can try shaving your arm hair until you run out 🙂 And here are a few other suggestions at Stack Exchange.

Answered by JoeFish

Answer: The Clever Shortcut

Forget the stone. Turn an old cup upside down and run the blade across the bottom of it first on one side and then the other. You will be surprised at how sharp it gets. I learned this from my granny. It’s quick, easy and cheap.

Answered by mike feeney

Answer: The Texta Trick

The hardest part of sharpening a knife for the first time is finding the right angle. Maintaining that angle isn’t so hard once you get used to it. Once you have some experience, you’ll be able to tell by the sound and feel of the edge sliding across the stone.

If you place the knife at a shallower angle than the edge, and slowly tilt it to a steeper angle, you can see your oil or water squeeze out from under the edge and form a thin line along the edge just as you reach the correct angle.

Another trick is to run a texta or other permanent marker along the edge. As you remove material, keep checking to see if you’re removing all of the black from the edge. If there’s still some marker along the “blade side” of the edge, your angle is too steep. If there’s still some along the “air side” of the edge, your angle is too shallow.

I usually start with either my coarse or medium stone, depending on how dull the knife is to begin with. I do five strokes on each side, then four, then three, two and one. If I started with the coarse stone, I move to the medium stone at this point and repeat the process.

To see if it’s sharp, I use my fingernail. I run my thumbnail perpendicular to the edge of the blade. If it catches, I know it’s sharp enough to move on to my finest stone. If not, I do another 10 strokes (switching sides between each stroke) on the medium stone and test again.

Answered by Adam Jaskiewicz

Answer: Odds And Ends

Another good test for sharpness of a knife is to hold the edge straight up so you can look along it. With a light above you (a point source of light would be best), look for any reflected light from the edge. A dull knife will show a visible reflection. Only once my knife passes the reflection test do I bother to test cutting paper with it.

For coarse sharpening, I like diamond stones, in two different grits depending on how much sharpening must be done. These are nice because water is a good lubricant. Once I get past that point, I use a ceramic stone to touch up the edge. If the knife is close to being sharp, I’ll skip the diamond stones completely.

Of course, always take care when sharpening a knife. Hold the edge in a way so you will not carelessly slice your hands while sharpening.

Answered by woochips

Answer: In Conclusion…

Sharp tools and knives are a joy to work with and produce faster, better results and do so safely.

The best book on the subject is The Complete Guide to Sharpening. My library has a copy, so check there first.

With good practice, anyone can learn to sharpen well. But you’ll need to be able to recognise a sharp edge, correct honing angles, and learn how long to hone at each step. Developing those skills with tools you’re trying to work with can be very frustrating. Consider paying someone to sharpen for you to give you something to compare to, and pick one tool or knife to learn on as you go.

Kitchen knives are generally difficult to sharpen because they have a changing-radius curve. Getting the right angle can be difficult. But once your knives are sharp, take care to keep them that way. Make sure the food you cut is supported by a surface that is softer than the knife, like a bamboo cutting board.

Use a honing steel to touch up the edge often. Avoid pushing a knife through food (like an axe). Instead, draw your knife back and forth (like a saw). Don’t let the sharp edge bump in to dishes or other utensils when washing your knife. Protect it from rust by drying it quickly and oiling it if you don’t plan to use it for a while. And be careful about where you store sharp edges – knives don’t belong in drawers.

Answered by Jay Bazuzi

Think you know the secret to sharpening a knife? Leave your suggestion in the comments or submit it at Stack Exchange, an expert knowledge exchange on diverse topics from software programming to cycling to scientific skepticism.

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