How sharp the knives turned out: We analyzed sharpness using a scientific tool called the Edge-on-Up, which measures the force needed to cut a standard reference material.

When the sharpener has more than one setting, the coarse setting is the sharpener and the fine one is normally similar to a honing steel. The electric Chef'sChoice 130 Professional Sharpening Station is simple to use and works well on many different sizes of blades, while the manual Longzon 4-in-1 offers similar quality with a low price tag. For those on a budget, the electric Presto EverSharp is excellent, too. How We Tested

Finish with a honing steel for best results. Rinse and dry the knife. You may also need to clean up the area around the whetstone. We rate each knife sharpener on how easy it is to set up and use, plus how easy the instructions are to follow. Things we learnt testing knife sharpeners It really depends on how much you use them and how much abuse they take, but knives generally need sharpening once or twice a year. If a knife feels dull or has trouble cutting, sharpen it. Just note that every time you sharpen a knife, it removes a little bit of metal. After many repetitions, there won't be enough left to sharpen, and it'll be time to replace your knife.

A whetstone is much harder to use. To get a good result, you need skill and practice, plus considerable patience. We did not expect a knife sharpener at this low of a price to work as well as it does, but the Longzon 4-in-1 really delivers. As the name suggests, the manual sharpener has four slots—three successively finer ones for standard knives and an extra-wide one especially for sharpening scissors and shears. Some manual sharpeners take a little practice to use correctly, but the Longzon's design and included directions make things simple. There's even a QR code link to video instructions if you're more of a visual learner. Sharpening a knife blade removes tiny bits of metal, and those will need to be removed from the sharpener once in a while. Many models have a compartment in the bottom to collect metal filings, which you can simply dump into the trash and wipe clean with a wet cloth. (If there's no compartment, turn the unit over and lightly tap to get the filings out.) You can also clean the abrasive parts with a cloth or a soft brush dampened with water; make sure to let everything dry completely before using again. Unless the directions say otherwise, it's not a good idea to use soap or any kind of oil to clean a knife sharpener, as you can damage the abrasive. This process is essentially the same with both a manual and electric sharpener, but the motorized abrasives in an electric model will do more of the work for you. The most important thing is to try to use the same amount of pressure and the same angle with each pull through the slot—different models of sharpener make this easier or harder, depending on their design. Unless the directions specify otherwise, it should take three to five pulls through the coarse slot, and then just a couple through each finer slot, to sharpen the knife. If it's not as sharp as you like, try a few more pulls through the finest grit slot, and if that doesn't work, try the whole process over again.Rebecca Treon, who also updated this piece, is a food writer, experienced home cook, and mother of two. Her work has been featured in BBC Travel, Huffington Post, Hemispheres, and Thrillist. A whetstone combined with a honing steel gives the best results (better than knife sharpeners). But (and it's a big but) only use this method if you know what you're doing. Otherwise, you risk damaging the cutting edge of your knife. All that’s left to do is dig out your blunt and damaged Global Knives and get them sent off to us to get them sharper than new!

We then sharpen the knife with its dedicated knife sharpener according to the manufacturers' instructions. To discover the best knife sharpeners on the market, we collected an array of dull knives—plus several boxes of Band-Aids—and tested their performance slicing through paper, carrots, and tomatoes (and a baguette, for serrated blades), both before and after sharpening. We also measured each knife's sharpness scientifically, using an Edge-on-Up tool to record the exact amount of force needed to cut through a standard material. Hold the knife at about a 22-degree angle to the stone. 90 degrees is your knife placed on the stone as if you were going to cut through it. Tilt the knife halfway between that and the whetstone and you'll be at 45 degrees. Then tilt it halfway between that and the stone, and you'll be at around the correct angle you need. If your knife sharpener has a fine or honing setting, run it through that once or twice after the coarse setting. Do this in the same way, but with less force. To keep your knife sharp, use the fine setting once after every couple of hours' use.Handheld manual knife sharpeners are designed to keep your blade fresh, and you should use them to top up the blade after every few hours of use. An electric knife sharpener or whetstone would be your best bet for a fully dulled knife. Brod & Taylor Professional Knife Sharpener: It looks like a piece of contemporary sculpture, and its maker claims that its spring-loaded design is foolproof to use, but we had to manually hold the unit open to insert the knife and weren't able to get very good sharpening results at all. Add a hefty price tag, and you've got a sharpener we wouldn't recommend. Repeat this action three to six times. You can go for three if your blade is just a bit dull, and more if it's blunter. Design: We highlighted sharpeners that featured multiple stages for maximum efficiency or different slots for different blade sizes. Knife sharpeners can be bulky, so we also focused on compact sizes that you could store easily in your kitchen. Work Sharp Electric Culinary E2 Kitchen Knife Sharpener: This sharpener is easy to use and has an excellent price for an electric model, but you get what you pay for. We found that it did just an OK job at sharpening, while its feet let it slide around on the countertop, which is a definite safety hazard.