It seems counterintuitive, but it’s a fact: Sharper knives are safer to use in the kitchen. The less resistance you have when cutting food, the less risk of slippage,
which can be grim (to put it...bluntly). Keeping knives sharp also means easier, more enjoyable food prep, AKA no weeping tomatoes or stubborn squashes.

So the issue is not if you should sharpen your knives, it’s how. Because not all knife sharpeners are equal.

Pull-Through Sharpeners vs. Whetstones

A pull-through sharpener is compact and efficient, perfectly viable to use for the thick and sturdy European knives it was designed for. Those knives can withstand the pressure. But do it too aggressively or too often and your knives risk losing their edge, shortening their life expectancies. For finer Japanese knives—or any kind of knife you want to last longer, really—a whetstone is the best way to keep your blades sharp. Because you're rubbing as opposed to grinding the blade, you lose a lot less metal in the process. (If you must use a pull-through, then we recommend the Vulkanus Classic Knife Sharpener, which is less abrasive than most commercial pull-throughs on the market.)

What *Is* a Whetstone, Exactly?

Also called a sharpening stone or water stone, a whetstone is quite simply a surface that sharpens steel objects. (The ‘whet’ has the same root as the term ‘whet your appetite’.) All the whetstones we sell in our store are Combination, meaning one side is coarser than the other. The coarser side is for fixing microscopic nicks and chips, and the smoother side is for fine-tuning the blade. Most whetstones have numbers on them, such as 1000/3000, that correspond to the coarseness (or grit) of the stone. The smaller the number, the coarser the grit. If your knives are really, really dull—or you know you won't sharpen them as much as you'd like to—go for a whetstone with the smallest grit.

Our #1 choice for a whetstone is the Kai 300/1000 or Wusthof 1000/3000. They perform almost identically, thanks to high-quality material that’s manufactured with longevity in mind. The key difference, besides the grit coarseness, is that the Kai whetstone comes with a stabilising rubber base. (If your whetstone does not have a base, make sure to place it on a damp tea towel while you sharpen your knives.) We also carry a Kai 1000/6000 whetstone for advanced cooks who are used to keeping their knives sharp and want a polishing stone just for that mirror finish. If you’re new to whetstones,
our best-of-value Niwaki 1000/3000 stone is a great introduction to the practice.

What’s the Time Commitment?

Start to finish, depending on how many knives you have, the process of sharpening knives on a whetstone can take from 30 minutes to an hour. Don’t panic: You don’t have to do this every week! You only need to put in that time when your knives are dull. ‘And how am I supposed to know that?’ you may ask, rightfully annoyed. We like the tomato test: If you can’t slice through a ripe tomato in a neat and tidy manner, your knives need sharpening. The most frequent home cooks on our team tend to sharpen their knives once a month, schedule permitting.

As long as you’re careful, spending that hour with your knives and whetstone is relaxing and meditative. If you enjoy cooking,
there’s no better way to de-stress.

Double vs. Single

There are two kinds of knife blades: double-edged and single-edged. Double-edged blades are slanted on both sides and meet to form the edge, like the tip of a pencil, while single-edged blades are flat on one side, like the tip of a box cutter. Most knives we sell are double-edged, as that’s most suitable for home cooks—it’s easier to manoeuvre and less prone to cutting at an angle. Single-edged knives allow for extremely thin slicing (think about the pickled daikon
or ginger you might see alongside sushi).

The single-edged knife you’ve likely encountered before is a bread knife. The straight edge lets you slice through hard crusts, while the serrated grooves grip and smoothly cut through the bread without compressing it.

The Nitty-Gritty: How to Sharpen

Submerge your whetstone in water for up to fifteen minutes—enough time for a light film of water to be visible on the surface. As it soaks, set up your sharpening station. Placing your whetstone on a damp tea towel will prevent it from sliding. Make sure kids and pets will not be able to enter the room as you sharpen. Keep a glass of water nearby; you’ll need to keep sprinkling water
over the stone as you work so that film stays intact.

double-edge blade sharpening

To sharpen a double-edged knife:

Most of the knives we sell at Borough Kitchen are double-edged since single-edged knives are highly specialised.

  1. Lay the whetstone down so the coarse side (the side with the smaller number) is facing up. Place one side of the blade onto the whetstone. Starting at the blade tip, position the knife at an angle of about 15° over the whetstone (see diagram above). Applying a little pressure, slowly move the blade toward and away from your body. Repeat this process until you feel a fine burr. Keep count of exactly how many strokes you make. You’ll need to do the same amount of strokes on the other side of the knife to have a symmetrically-sharpened blade.
  2. Turn the knife over and repeat for the other side of the blade, using the same number of strokes. When done, rinse the whetstone and the knife with water. Wipe the knife dry.
  3. Turn the stone so the polishing side (the side with the bigger number) is facing up. You don’t need as many strokes to polish—up to five strokes on both sides of the knife should do the trick.
  4. To check if the knife is sharp enough, wipe the knife clean and do the tomato test: Take a tomato and cut it in half. If the tomato shows any resistance, your knife could use a few more strokes on both sides.
  5. Admire your handiwork and smile in anticipation of the good food in your future.
double-edge blade sharpening

For single-edged blades, the process is a little different:

  1. Lay the slanted side of the blade onto the whetstone. Starting at the blade tip. Pull the knife at an angle of 45° over the whetstone (see diagram above), moving the blade with light pressure toward and away from your body. Repeat this process until you feel a fine burr. Keep track of the number of strokes you make.
  2. Turn the knife over and lay the straight side of the blade flat on the stone. Repeat, but with only 1/10 of the number of strokes as the other side. When done, rinse the whetstone and the knife with water. Wipe the knife dry.
  3. Turn the stone so the polishing side (the side with the bigger number) is facing up and repeat, bearing in mind you don’t need as many strokes to polish.
  4. When done, rinse the knife with water and wipe clean. Do the tomato test and adjust as needed.

For an even better understanding—especially if you read the above and wondered what on earth a ‘burr’ feels like—watch this quick video from our friends at Blenheim Forge. (Psst: If you like the look of their knives, check out the exclusive collection we co-designed with them. It’s gorgeous and
more practical than your standard carbon steel knives.)

Still Not Confident?


We understand—your knives are precious! That’s why we have complimentary knife sharpening tutorials in each of our London stores at the beginning of every month (see the schedule here). We can also sharpen knives for you with our premium knife sharpening drop-off service, which is free of charge once a year for 10 years after the purchase of any Kai Shun Classic, Premier or Nagare knife from our store, and £9 per knife otherwise. Read more about it here.