How to Sharpen a Santoku Knife- A Step-By-Step Guide

The Santoku is an aptly named versatile knife with Japanese origins that can be used for cutting meat, fish, and vegetables. The name, when loosely translated to English, means ‘three purposes.’

It is not your regular knife as it has a few attributes that separate it from the rest, which is why we are going to look at how to sharpen a Santoku knife specifically.

The Santoku knife is a bit shorter than your regular kitchen knife, coming at an average of 15 to 18 inches instead of the standard 20 inches.

Its knife blade stands taller when chopping, providing more clearance for the knuckles on your knife-hand. The tip is curved like a sickle, making it less likely to break but at the same time limiting its operation when it comes to precise cutting situations.

We shall combine its usage and geometry in this article to justify our recommendations on methods and tools of sharpening it.

How Often Should the Santoku Knife Be Sharpened?

The frequency of sharpening is not constant and largely depends on the intensity of usage of the knife. Many professional chefs use a moderately ripe tomato to determine if the knife is at the sharpening stage.

If you can easily cut through the tomato without having to pierce an entry point using the tip of the knife, it is still okay. Sharpening any knife too frequently hastens the wear and tear as a part of it is lost with every session.

With time you will develop your own routine, although Santoku knives with extra strong blades generally don’t need too much maintenance.

Which Sharpening Tools Should Be Applied?

There is an array of tools that have been used over the years to deliver this critical service to a dull knife. You can use a manual or electric knife sharpener and a sharpening stone.

A manual or electric knife sharpener is easier to use than sharpening stones as the sharpening process for these is simpler. Their main shortcoming is their lack of capacity to accommodate the needs of specific knives, which renders them inadequate for an oddly shaped Japanese knife like the Santoku knife.

Pull-through sharpeners are not recommended for such knives as they may lead to damage to your knife. They remove more material than is necessary for your knife to be sharp, leaving you with an oddly shaped knife and forcing you to keep sharpening the knife; it is a vicious cycle because now the microchips produced have to be taken off as well.

You may opt for them if you are operating a large volume outfit like a butchery or hotel, and you don’t mind replacing your Santoku knives often. Otherwise, they are usually used on less expensive knives that are easily replaced.

We shall pay more attention to sharpening stones in this article as they have been tried, tested, and recommended for sharpening a Santoku knife. They give you control over the contact level the knife blade gets with the sharpener as you can feel and see the progress.

You can learn more about the benefits of manual and electric knife sharpeners from our in-house expert and review the best of them in this general knife sharpening article.

Using Whetting Stones to Sharpen a Santoku Knife

You should start by preparing the stones for the task at hand. They often need a bit of water to make the process smooth. Depending on the whetstones you are using, they may or may not require soaking.

Some just need to be slightly wet, so you can use a spray bottle. The instructions are usually readily available within the pack.

Ensure the stone is flat before beginning as you want to maintain a regular angle between the knife and the stone throughout the process. The knife blade will otherwise not get that even smoothness necessary to cut through food that you are seeking. Thoughtful sharpening stone makers like Sharp Pebble always include a flattening stone in their package to facilitate this.

You can sharpen your Santoku knives like your other knives, with a 20˚ sharpening angle to the whetstone. However, this may have to be adjusted slightly to 15˚ if it is one of those Santoku knives with a Granton knife edge (the identical grooves on the sides of the blade meant to allow air in while slicing food to prevent the food from sticking to the blade for cleaner cuts).

Once you settle on it, hold the knife at this sharpening angle against the sharpening stone with your dominant hand. With the other hand holding the flat of the blade, push it in a stroke that ensures the entire length of the cutting edge touches the whetstone during the motion. Move your hands but try not to rotate your wrists at the end of every stroke so that you can maintain the correct angle.

Try and use the entire length of the stone as much as possible during the sharpening process. If you isolate one part of it, that part of the stone will wear out faster, distorting the angle and forcing you to flatten it again (if you can catch the difference in time).

Repeat the motion on the other side of the blade, ensuring the angle is the same. The motion for this sharpening method should become smoother as the knife blade sharpens. It should always be towards the flat of the blade, dragging the cutting edge on the stone during the sharpening process.

You will know if the angle is wrong if there is no change after a few strokes. This can also mean the knife was too blunt in the first place and probably needs more work. At some point, you will have to combine observation and experience.

Use the same motion for all the stones you are using to get the perfect balanced blade.

Whetstones are categorized according to the coarseness of their grain because they serve different purposes. Always begin with the coarsest and finish with the smoothest. The lower the grit rating, the coarser it is.

Where you begin will depend on the state your blade was in in the fast place. Sometimes it is not necessary to start very low; the knife could be in good condition that does not require all that rough filing.

Whetstone Grit Ranges Demystified

Low Grain

These stones are rated downwards of 1000 grit, making them ideal for rough sharpening and occasional repair of chipped blades. They leave the blade a little rough on the knife’s edge, though, requiring more refinement.

Regular Grain

We use these for normal sharpening of blunt blades that need a sharp edge. They are smoother than the low grains but still work by scraping metal from the blade’s cutting edge to make it thinner and sharper. They are rated between 1000 and 2000 grit.

High Grain

Whetstones above 2000 grit are all considered a fine grain and are used for finishing and sometimes for just honing the blade if you feel it is not sharp enough, but not enough to warrant a full-blown knife sharpening session. The finer grain can be used more frequently as it has less effect on the knife blade’s durability. They remove the fine scratches and burr left by the coarser stones.

Since a Santoku knife is made of more hardened steel than regular knives and has a curved tip, you can make it thinner and sharper without fear of breakage.

Therefore, to be fully sufficient, one will need three whetstone grades: coarse, middle, and fine.

This is well taken care of as we now have two-in-one whetstones in the market; some are even sold as a set for the price of one with variations of all the grades. A good illustration is the G-TING Knife Sharpener Kit currently available on Amazon.

If you don’t have the right equipment or you feel the process is overwhelming, you can always take the knife to be sharpened by a professional to achieve the knife edge you want. Quality Santoku knives don’t require sharpening very often.

Some knife makers like Oxford Chef even offer a free sharpening backed by a lifetime cash back guarantee in case you are dissatisfied with some of their knives, like the  7-inch Cutluxe Professional Santoku knife. This saves you from going through all this trouble if you can access their customer service.

A Santoku knife, if well maintained, can outlast all your other knives and deliver a lifetime of relaxing service. We hope you have learned a few great tips here on how to sharpen a Santoku knife.