How to sharpen a single bevel knife: Expert Tips & Techniques [VIDEO GUIDE]

Have you ever tried sharpening your own knives? Are you a novice or would you call yourself an experienced sharpener? You've probably already seen our Beginner's Guide to Knife Sharpening, but now there's an advanced tutorial to guide you through the world of single bevel knife maintenance.  

Sharpening (more common) double bevel knives has its specifics, but sharpening traditional Japanese single bevel knives is a whole other beast. You'll learn the anatomy of single bevel knives, the advantages, and disadvantages of using them. We touch on different kinds of steel, the construction, and the geometry of the blade. You'll be introduced to the terminology (simplified for easier understanding) and the tools required in the sharpening process. We'll guide you through the sharpening steps and we'll even add some hacks and tips for good measure.

Single Bevel Knife: What It Is, Benefits, and How to Use It

Single bevel knives have a bevel on the front (shinogi) side and a concave back (urasuki) side. Common types include deba, yanagiba, and usuba. These knives are designed asymmetrically for left or right-handed users, with the bevel on one side and a flat rim (uraoshi) around the concave back to reduce drag during slicing.

This sharpening guide is considered intermediate because we’ll cover more technical details about the process, focusing on the nuances that help sharpeners take their skills to the next level. Traditional Japanese knives, especially the single bevel types, have deep connections with Japanese cutting techniques and cuisine, and sharpening them requires both skill and understanding. It’s a process rooted in Japanese sword care, blending art and technique. Despite all the details we’ll cover, this guide is just an introduction. There’s always more to explore, and the more I discover, the more I realize there’s still so much more to learn.

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The Anatomy of a Single Bevel Knife

Uraoshi Side [back side of the blade]

The uraoshi is the flat rim-edge surrounding the concave urasuki on the back of the knife. This rim helps minimize drag while slicing and contributes to the overall strength of the blade. Proper maintenance of the uraoshi is crucial for preserving the knife’s sharpness and performance. It's important to note that sharpening the urasuki concave itself is a specialized task typically done by professionals and should not be attempted with standard sharpening stones at home.

Urasuki refers to the slight concavity on the inner side (single-bevel side) of traditional Japanese knives. Its primary function is to reduce friction during cutting and make it easier for food to separate from the blade. Additionally, the urasuki plays a key role in maintaining a consistent sharpening angle. As the knife wears down over time from regular sharpening, the urasuki helps preserve the blade’s angle, ensuring stable cutting geometry and optimal performance.

Shinogi Side [front side of the blade]

The shinogi line is the ridge separating the flat part of the blade from the bevel. When sharpening the shinogi side, it's essential to focus on the micro bevel—the tiny edge at the end of the bevel. Be mindful of its size, as a wide micro bevel can indicate improper previous sharpening.

Lefty, Righty

Single bevel knives are asymmetrical and designed for a specific hand. If the shinogi line and bevel are on the right side, it’s a right-handed knife; if it’s on the left, it’s meant for left-handed use. This design is permanent and cannot be altered, so be careful when purchasing. Left-handed single bevel knives are rarer and typically more expensive.

Steel Types: Kasumi & Honyaki

High-quality steel, combined with the skill of an experienced blacksmith and grinder, results in easier sharpening and a stronger edge. When choosing a new single bevel knife, traditional steels like Aogami, Shirogami, and Ginsanko are highly recommended.

In terms of blade construction, there are two main types:

• Honyaki knives are made from a single piece of steel. These represent the pinnacle of Japanese knife craftsmanship—rare, expensive, and highly valued. However, they tend to be harder to sharpen and more brittle compared to kasumi knives.
• Kasumi knives are more common and are crafted by forging together two or more steels. The harder hagane forms the cutting edge, while the softer jigane provides support and flexibility. This combination makes kasumi knives easier to sharpen and more forgiving in daily use.

Advantages of Single Bevel Knives

Cutting Techniques

Single bevel knives are specialized tools designed for precise cutting techniques, especially in sushi preparation. Their asymmetrical design allows for ultra-thin, precise cuts, making them ideal for delicate tasks like fish slicing.

However, single bevel knives are not suitable for cutting through thicker ingredients. Due to their asymmetrical blade geometry, they can easily bind or wedge when slicing through dense or thick foods.

Half Angle

The cutting angle is different on each side of the blade. The uraoshi side is flat, while the shinogi side typically has an angle of about 15 degrees. This unique geometry allows for a thinner, sharper edge, even if the blade is thicker at the spine, making single bevel knives extremely efficient.

Grinding, Thinning, and Sharpening

Sharpening a single bevel knife is not just about honing the edge—it’s also about maintaining the geometry of the blade. As you sharpen, you should raise the shinogi line the same amount as you remove material from the edge. This keeps the blade’s shape consistent, even after multiple sharpenings, unlike double bevel knives.

Disadvantages of Single Bevel Knives

When you first use a traditional single bevel knife, adapting your cutting technique is crucial. The blade can easily be drawn away from the shinogi side, so careful technique is essential to avoid errors in slicing. Also, the knife’s response to sharpening can vary significantly, depending on the maker’s skill and attention to detail. While high-quality steel is essential, the expertise of the blacksmith and grinder is equally important.

Whetstones for Sharpening Single Bevel Knives

Sharpening stones are an essential tool for sharpening single bevel knives. If you're purchasing a knife from us, feel free to reach out to our customer service for advice on selecting the right sharpening stones. While there’s no one-size-fits-all, using quality stones will yield the best results. Different stones with the same grit can produce very different results. For a basic sharpening setup, here's our advice: start with a high-quality stone flattener, as sharpening stones must remain flat. You’ll also need a good rubber stand, a dressing stone (nagura), and a leather strop for extra finishing.

Basically, you’ll need 2–3 stones for sharpening. For usuba and yanagiba knives, a medium and fine stone may be enough, but for deba knives, which tend to endure more wear, you’ll likely need a coarse stone as well.

In some cases, you can use a diamond flattening plate (e.g., 400 grit) as a flattening stone. If the blade has significant damage, this plate can also serve as your initial coarse grit stone.

While synthetic stones work well for lower grits, traditional Japanese natural stones are essential for achieving the best kasumi finish and bringing out the beauty of honyaki knives.

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Essential Steps to Sharpen a Single Bevel Knife

Learning how to sharpen single bevel knife edges can initially seem daunting, but with the correct approach, you’ll soon master the process. Below is a detailed walkthrough that should help both beginners and experienced cooks achieve a razor-sharp edge.

Now that we’ve covered the theory, let’s get to the practical side of sharpening your single bevel knife.

Before starting any sharpening on traditional Japanese knives, it's important to protect the Japanese wa handle—especially if it's made of magnolia wood, which can stain easily. You can protect the Wa handle by wrapping it with masking tape or plastic wrap. Masking tape is a simple and effective way to prevent water and slurry from staining the wood. If you're sharpening for an extended period, you can also use a plastic bag secured with a rubber band for extra protection.

Uraoshi Process [Back Side]

We advise starting the sharpening process on the back side (uraoshi) for a good reason. When a knife becomes dull, it often develops microchips, dents, and roll-overs, which tend to appear more on the back than the front due to the blade’s single bevel geometry. By addressing this side first, we can minimize steel removal and push back some of the damage instead of grinding it away entirely.

That said, we must be careful not to over-sharpen the uraoshi side. The urasuki (the integral concave section) needs to stay concave throughout the knife’s lifespan. Over-thinning the uraoshi—especially on a new knife—creates a delicate, brittle edge. If the uraoshi becomes too thick and the urasuki starts to disappear, the knife will need urasuki restoration—a process only an experienced sharpening master can perform using a large sharpening wheel, which cannot be replicated on flat sharpening stones.

We advise starting the first uraoshi sharpening with a 1000–1500 grit stone, ensuring it is completely flat. Place your fingers as close to the edge as possible and apply light pressure while pulling the blade towards you. The downforce should be concentrated where the damage is, as pulling and pressing in this motion helps to unroll the edge while also minimizing scratches on the stone.

This sharpening phase should be extremely short—every extra stroke is unnecessary. The goal is to preserve the urasuki concave area, so as soon as the rolled-over edge stops biting into the stone, you’ve done enough. This usually takes just a few strokes.

Blade placement is also crucial. Holding the knife perfectly parallel from heel to tip ensures that the urasuki remains correctly aligned along the entire length of the blade, which directly improves cutting performance.

Shinogi Process [Front Side]

The Shinogi sharpening process focuses on refining the entire steel section between the shinogi ridge and the edge. There are two traditional edge types we can achieve, each using a slightly different sharpening technique. Both are correct, with subtle differences in performance and characteristics.

Before diving into the details of these edge types, it's crucial to ensure the surface is evenly aligned, without high or low spots, particularly near the edge. When sharpening a new knife, these irregularities will become apparent early in the process. Taking the extra time to remove them now will create a solid foundation for sharper edges and smoother, faster sharpening in the future.

As you sharpen, you’ll need to decide between a Hamaguri (convex) edge or a Beta Togi (flat) edge, depending on your preferences and the knife’s original geometry.

Before sharpening, examine the original edge of your knife to determine which style suits it best. If you prefer, you can transition from a flat edge to a Hamaguri edge to adjust the knife’s cutting characteristics.

Finger Placement

The primary difference in sharpening a Hamaguri edge versus a Beta Togi edge is the finger placement on the blade. To sharpen a Hamaguri edge, all three finger positions are needed. For a flat Beta Togi edge, only the middle finger position is used, while the rest of the technique remains the same.

Three positions guide the sharpening process:

1. Shinogi ridge
2. The transition line between hard and soft steel
3. As close to the edge as possible

In the video and this article, we will demonstrate how to sharpen a Hamaguri edge. For a flat Beta Togi edge, the process is the same, but you’ll only need to use the middle finger position.

Soft Steel [Jigane] Sharpening

First, sharpen the soft steel, raising the shinogi line just enough to match the amount you’ll raise the edge. For example, if there are 1mm chips on the edge, raise the shinogi line by 1mm. Place your fingers in position 1, just below where the shinogi line corresponds on the uraoshi side, and start sharpening.

For heavily damaged deba knives, use a 220–400 grit stone. For yanagiba and usuba, start with 1000 grit, or 3000 grit for frequent sharpeners. Apply pressure with your best 2–3 fingers, close together, aligned with the middle of the stone. This is crucial for sharpening on the shinogi side, especially with curved blades like deba knives. Keeping the fingers aligned prevents slight edge deformations.

When sharpening with 1000 grit, avoid creating too much slurry, as it can cause scratches beyond the shinogi line. Sharpen along the entire length of the blade, using the blurry finish to identify areas that need more attention. 

Hard Steel [Hagane] Sharpening

Next, sharpen the hard steel that holds the edge of your knife. This requires more precision and a slightly steeper angle.

Apply pressure with two fingers close together in position 3, as close to the edge as possible. If your knife previously had a strong hamaguri edge, this is enough. However, if you had a flat edge and now want a hamaguri edge, raise the blade (shinogi ridge) about 1–2mm in addition to the low finger position. Apply pressure away from you and gently pull back. Continue this motion until all chips and nicks are removed and a burr is formed.

Uraoshi Process

Using a 3000 grit stone, flatten the stone and place the knife parallel to it. Lightly press with your fingers in position 2, at the transition between the hard and soft steel, applying pressure towards you. Since the uraoshi side is flat, you can slightly spread your fingers. Use a few light strokes up and down to reduce the burr, then flip the knife over. Check for the burr with your thumbnail.

Shinogi Process

Using the 3000 grit stone, we do it all over again exactly like in the previous step, but with slightly lighter pressure.

Uraoshi Process

Prepare the 5000 grit stone, flatten it, and place the knife parallel to it. Using very light pressure with your fingers, draw the blade towards you in position 2, at the transition between the hard and soft steel.

As you continue sharpening, observe how the flat uraoshi rim gradually widens. If the back-spine uraoshi rim becomes too wide, move your finger position closer to the edge. If the front-edge uraoshi rim widens too much, shift your finger position closer to the spine.

To check, use two long flat surfaces. The uraoshi rim should be parallel to the flat surface above the shinogi line.

Shinogi Process

Using a 5000 grit stone, create slurry with a nagura or dressing stone, then find your finger position (position 2) between the hard and soft steel and begin sharpening. Take your time here, creating a lot of slurry. This process will blend both bevels into a slightly convex shape, creating a kasumi-type finish. When satisfied with the result, clean and flatten the stone, and you're ready for the final step.

At this point, the knife is sharp. You can add a micro bevel and remove the burr, or continue sharpening with finer grit stones or natural stones. For stainless knives, this stage is about 95% as sharp as carbon steel knives, like shirogami, which benefit from further refinement on 8000–10000 grit stones.

Beyond 8000 grit, such as 10000 or higher, the focus is more on aesthetics than sharpness. For high-end honyaki knives, this is considered traditional Japanese polishing, similar to techniques used on Japanese swords. Different Japanese natural waterstones up to 30000 grit, along with fingerstones, can be used. The final step, nugui, involves rubbing a mixture of powdered iron oxide or magnetite with clove oil to darken the jigane and highlight the hamon line.

Examine the edge

Before adding a micro bevel, do a few light strokes on the uraoshi side, from bottom to tip, and a few light strokes on the shinogi side in the low finger position, also from bottom to tip. Flip between the uraoshi and shinogi sides two or three times.

Now, decide whether to add a micro bevel. To check the edge, press lightly with a fingernail to feel for any steel deformations. A small deformation (1–2mm) is acceptable for yanagiba and usuba knives, but for a large deba, it's better to avoid any deformations, as they can damage the edge quickly. You can fine-tune this with the micro bevel.

Micro bevel

I always apply a small micro bevel on yanagiba and usuba knives, and a slightly larger one on deba knives. During cutting, you can observe how the edge holds up; if it’s too brittle, add a micro bevel. Some sharpeners use a micro bevel as a shortcut for quicker sharpening, but while it works a few times, it’s not ideal long-term.

To create a micro bevel, clean and flatten your finest stone. Start lightly at the shinogi line and lift the angle about 2–3mm (roughly the thickness of a 50-cent coin). Use finger position 3, as close to the edge as possible. A few gentle strokes from bottom to tip should suffice. Then, turn the knife to the uraoshi side and make a few gentle strokes from tip to bottom.

Honing or removing the burr

At this point, the knife should be perfectly sharp. To check, do a fingernail test—it should have a smooth yet fine, catchy feeling. This catch indicates a micro burr is still present. There are a few options for dealing with it.

→ Leave it or remove it on your jeans?
This method works best on simpler steels like shirogami, where the burr will easily come off. However, you may still have some micro burr remnants, which can be beneficial for cutting vegetables with skin.

→ Remove it with stones
The best method, but it requires an experienced sharpener. You’ll need a super fine grit stone (at least 8000, depending on the steel). Continue lightly sharpening both sides while constantly checking for the burr. The right grit is when the burr is no longer felt.

→ Remove it with a leather strop
In our opinion, this is the best method for producing a very fine edge, especially for slicing fish and meat. It’s simple—just follow our advice and draw the blade back across the strop, alternating 3–4 times.

Conclusion

Sharpening Japanese traditional single bevel knives requires patience, skill, and a deep understanding of the blade’s geometry. By following this intermediate guide, you’ll be able to restore and maintain the sharpness of your knife while preserving its traditional characteristics. Keep practicing, and as you gain more experience, you'll unlock the true potential of your knife.

We'd like to share a wise thought our Luka thought of and everyone at SharpEdge lives by: “Knowledge is like shit –  if you spread it around wisely, it’s fertilizer.” 

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Happy sharpening!