Fans of the katana love the sword’s razor sharpness, allowing its wielder to cut down an opponent with a single strike ala-Battousai. And although Japan has experts dedicated to polishing and sharpening a katana, ordinary folks can also keep their Japanese swords as razor-sharp as their ancient counterparts. Yes, even in the garage.
How to sharpen a katana is a concern of many first-time katana owners. Luckily, you can maintain your sword’s edge with a few tools, patience, and this guide. We will also throw in other information to make your katana sharpening journey more worthwhile.
Let’s start.
The Togishi: The Masters of Katana Sharpening and Polishing
Learning katana sharpening roots is as essential as knowing how to make a katana. Let’s travel back to the Kamakura Period between 1192 and 1333 to appreciate the value of sharpening a katana.
Many Japanese consider sharpening katana the highest artistic and spiritual form in the land’s centuries-old swordmaking tradition. While modern swordsmiths polish and sharpen their creations, feudal Japan gave the task to katana polishing specialists – the Togishi.
Modern Japan still has Togishi, but only a handful. Why? Not everyone who knows how to sharpen a katana can pass the Society for the Preservation of the Japan Art Sword’s (Nihon Bijitsu Token Hozen Kyokai) stringent regulations and licensing requirements.
Did you know a NBTHK-licensed Togishi must undergo a decade of Togishi apprenticeship? That’s twice as long as the swordsmithing training period.
Unsurprisingly, Togishi are a natural treasure. And you wouldn’t trust just anybody else to sharpen your katana.
Please don’t be confused with the katana polishing vs sharpening divide. Polishing involves sharpening the katana’s leading edge (Ha) and giving the blade (Nagasa) its characteristic look and other attributes.
Polishing a katana or any Japanese sword can take weeks, while sharpening can only last a few hours. This differentiation reinforces the notion that anyone with a good understanding of katana swords can sharpen them, even at home.
The Essential Katana Sharpening Tools
Sharpening a katana isn’t different from retaining the edge of an ordinary kitchen knife or other bladed weapon. However, the procedure requires a few things your butcher’s knife might not need to sharpen its edge.
Flat whetstone – Although you can use synthetic whetstones (those we use to sharpen ordinary knives), nothing beats a 1000- to 1500-grit flat whetstone. It’s also less expensive than synthetic versions. Alternatively, you can use several 3M emery sandpaper ranging in coarseness from 400 to 2,000 grit.
Japanese water stones for sharpening katana. Image by Robin Wood.
- General-purpose lubricant or oil – Please resist the temptation to use vegetable oil, although mineral oil can work. Sharpening a katana requires a general-purpose lubricant (i.e., 3-in-1).
- Work board – You’ll need a flat and firm surface to rest the katana’s Nagasa.
- Spray bottle with clean water – Sharpening katana requires removing residue from the whetstone’s surface to keep it edgy.
- Clean cloth – You need two pieces of cloth: one for holding the katana and another for wiping and cleaning the Nagasa. Although some recommend a lint-free, non-abrasive fabric, any clean piece of cloth will suffice.
- Foam or paper – How can you check if the katana is sharp enough? You cut with it, of course.
How to Sharpen a Katana
Displaying your katana would feel more rewarding, knowing you have also sharpened it. As mentioned, sharpening your katana should be as easy as retaining your kitchen knife or utility knife’s edge. You only need to observe several things.
Ensure the environment is free of distractions and safe.
Some katanas aren’t sharp. For instance, the Iaito doesn’t have the characteristic razor-sharp Ha of a Shinken or katana. This sword is excellent for beginners learning Iaido without harming themselves or anyone else.
We assume you have a sharp Japanese sword. Otherwise, you won’t be reading this. Hence, your first task is to ensure a distraction-free and quiet environment. You’ll be working with a bladed weapon. Losing focus can translate to accidental cuts and similar injuries (or lose a finger).
Soak the Japanese water stone in water.
Water stones or whetstones are porous for a reason. These tiny holes accommodate abrasive grains coming off the sharpening process, allowing the whetstone to retain its functionality.
However, you cannot leave the whetstone dry because it can create a highly abrasive surface, nicking and damaging your katana’s Nagasa. Soaking the whetstone in clean water for 15 to 30 minutes should keep it saturated longer when sharpening katana.
Clean the katana to remove surface contaminants.
Dust and particulates can accumulate on the katana’s surface over time, unless you keep the sword in a climate-controlled, airtight, vacuum chamber. Oil from the previous sharpening or polishing activity can also form gunk. You might want to remove these surface contaminants before placing the katana on the work board.
While “wetting” the water stone, grab your cleaning cloth and hold the katana. Slowly and carefully run the thick fabric across the Nagasa, clearing all signs of dust, particulates, oil, dirt, and other residues.
You’re ready to give your katana’s sharp edge back.
Sharpen the katana.
A man sharpening a katana. Screenshot of YouTube video by Old Pueblo Forge.
Returning a katana’s sharp edge can be a beginner’s nightmare because it requires certain techniques. Fortunately, practice and sharpening frequency can strengthen muscle memory, making the process second nature.
- Secure the whetstone on the work board. If using sandpaper, you can tape it to the wood to prevent the sandpaper from moving.
- Place a few drops of 3-in-1 oil (or any general-purpose lubricant) on the sandpaper. We recommend starting with 400-grit. You can forget this step if using the wet water stone.
- Wrap the katana’s tang with a piece of cloth to improve control and stability.
- Position the katana’s Nagasa on its side across the whetstone or sandpaper. Raise the sword’s Mune a little bit to obtain a 15-degree angle relative to the water stone’s surface. Ensure the Ha (the sharp edge) faces you, although some suggest doing what works best for you.
- Hold the katana’s cloth-wrapped tang and the Mune (backside). Pull (or push, whichever you prefer) the blade in one steady diagonal stroke, maintaining the 15-degree angle. Apply about 4 to 6 pounds of pressure with each movement.
- Lift the katana and reposition it on the whetstone or sandpaper. Please avoid sharpening katana in a back-and-forth motion to ensure consistent grid patterns. Repeat this action (“pass”) three to five times on each side.
- Apply water or oil on the whetstone or sandpaper after every three “passes.”
- If using sandpaper, note you must replace the sandpaper with a finer-grit after each sharpening cycle. For example, you can move to 800-grit sandpaper after the 400 grit, then 1,000-grit, and finally 2,000-grit.
Check the Ha’s sharpness.
What’s the point of executing all these steps if you still produce a dull blade? Although slashing a tatami mat is tempting, a piece of paper is enough. Alternatively, foam will do the trick.
Hold the paper and drive the katana across. You know you executed the steps properly if the blade cuts the paper seamlessly without irregular edges.
Other Methods of Katana Sharpening
Some katana owners use other methods to sharpen their swords. After all, the traditional whetstone-based sharpening technique is time-consuming. Moreover, you might have some tools in your garage or work shed to restore the katana’s sharpness.
Sanding Belt
This technique is perfect for katana owners pressed for time. Power it on and position the Nagasa on the sanding belt. You will have a sharp edge in minutes. However, many sword experts don’t recommend this method to beginners, especially those sharpening their katanas for the very first time.
Grinder and Similar Power Tools
Power tools can sharpen Japanese swords faster than sanding belts. Unfortunately, controlling the process is challenging for beginners. Moreover, the risk of damaging the katana is high because of the ultra-fast abrasive action.
However, power tools remain a popular choice for katana owners who need a more efficient way (read, “shortcut”) to restore the sword’s sharpness. Position the katana with its Ha facing up and tilt it towards the spinning grinder, maintaining a 15-degree angle. Repeat on the katana’s other side.
Image of a man using a belt sander to sharpen katana. Screenshot of YoutTube video by Freestyle Swordsman.
An Expert Local Swordsmith
Some folks consider people who let professionals sharpen their Japanese swords “lazy.” Maybe. Maybe not. They might be clueless about the correct katana sharpening procedure or lack the confidence to perform the steps. Some katana owners are also busy.
We don’t find anything wrong with bringing your katana to a local swordsmith to sharpen and polish it. On the contrary, it proves the owner values their katana so much that they believe only professionals can restore the sword’s sharpness (like Japanese Togishi).
Although it’s unlikely you’ll find an NBTHK-certified Togishi in your community, you can contact your katana dealer for recommendations. A quick Google search can also lead you to someone knowledgeable and skilled in the art of sharpening bladed weapons, especially katanas.
Note American smiths typically charge $120 to $300 to sharpen Japanese swords. The price could be higher or lower depending on some factors, including the blade’s level of “dullness.”
The Bottom Line
Anyone can learn how to sharpen a katana. So, bring out your katana and start practicing the art of sword sharpening in order to make your sword as sharp as possible. You’ll never be a Togishi, but you can guarantee your katana’s condition and functionality. And that’s vital in katana ownership.
