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Katana Blade Maintenance

The Do’s and Don’ts of Caring for a Katana

The traditional Japanese katana is one of the most popular swords in the world. Owned by martial artists and collectors, it features a curved, single-edged blade, usually made of high carbon steel. Like other swords, however, owners must take certain precautions to preserve the strength and integrity of their katana.

Regularly remove it from the sheath

If you keep your katana in a leather sheath, be sure to remove it regularly. When swords are stored in a leather scabbard for a long time, it creates a damp environment while promoting rust and corrosion. This is because leather absorbs moisture from the air, which in turn reaches the blade of your katana.

Do not touch the blade with your fingers

Try to avoid touching your katana blade with your fingers. This will not cause immediate damage, but will encourage rust and corrosion to form later. You see, the sweat and natural oils from your fingers will transfer to the blade, and if not cleaned in time, it can cause rust

Coat with oil

The most important step in protecting and preserving a katana is to oil the blade. Just as wax protects a car’s clear coat from moisture damage, so does the oil on a katana.

Of course, there are dozens of different oils and petroleum products you can use on a katana, although many experts recommend choji oil. Combining mineral oil and clove oil, it’s a safe and effective solution to protect your katana from moisture.

Don’t talk about your katana

What’s wrong with talking on your katana? This is an old label that is to protect the blade from accidental moisture. If you speak while holding your katana under your head, some of your saliva can get on the blade and it only takes a small amount to start the destructive chain corrosion cycle.

Treat wooden hedges with oil

In addition to oiling the blade of your katana, you should also oil the wooden handles. Wood is very porous and, depending on the ambient humidity, it absorbs or releases moisture. If your katana has a wooden handle and you store it in a place with low humidity, the wooden handle can dry out and eventually crack. Fortunately, such problems can easily be avoided by oiling the handle.

Don’t forget to inspect your katana

You should take your katana out of storage for a brief inspection at least once a week. During this inspection of your knives, swords, sabers, check for rust, metal oxidization, chipping or other damage.


Looking to buy a traditional Japanese katana? Well, first let me congratulate you on your decision. There are dozens of different swords, but the katana is arguably one of the best. If not the best due to its unparalleled level of strength, versatility, quality and attention to detail. And with its copper finish and material or metallic Japanese swords with thin thickness. Like all swords, however, the katana requires some basic care and maintenance to preserve its original qualities. But you’ll want to avoid making the following five mistakes when servicing your katana.

Storage with the edge down

The rule of thumb for storing a traditional Japanese katana is to place it with the cutting edge up. This is how samurai warriors carried the katana, and it is also the recommended method for storage. Storing your katana edge down in its sheath increases the risk of damaging the blade.

Katana Blade

Storage in a leather sheath

Why not store your katana in a leather sheath? Although it looks harmless enough, leather sheaths don’t offer much protection. They are too flexible and contain too much moisture to adequately protect katanas or other swords from long term damage. Consider storing your katana in a sheath instead. There are lacquered wooden scabbards, for example, which are stronger and more durable, making them the perfect alternative to a leather scabbard.

forgetting about humidity

Finally, don’t neglect humidity when maintaining and storing your katana. High humidity means there is a lot of water vapor in the air, and too much water vapor will saturate your katana blade and contribute to rusting. Maintain the environment in which you store your katana at around 40-50% relative humidity to avoid damaging the coating.


The katana is undoubtedly one of the most prolific and recognized swords in the world. From Asia to North America, countless people collect this iconic sword or use it in swordsmanship-based martial arts. This is partly due to the superior quality of the katana blade. Made of high carbon steel and subjected to differential heat treatment, it is strong while remaining flexible and able to bend.

To obtain a strong blade, Japanese swordsmen would bend the katana blade dozens of times. It’s true that a common myth is that swordsmen bend the katana “thousands” of times, but that’s not necessarily true. If the different smiths had their own technique, most of them bent the katana 15 to 30 times. This was more than enough to achieve the desired effect, with each fold improving the properties of the blade.

engraved blade

Overview of the bending process

Swordsmen would bend the katana blade while the metal was still red and hot. After heating the metal – usually iron, carbon and alloys – the smiths would cut the blade in half so that it would bend across using a small hammer, then cut it in half in the longitudinal direction using a larger hammer. The swordsman continued this process until the desired effects were achieved. In most cases, Japanese swordsmen would not bend the katana blade more than 30 times.

Why was the katana blade bent?

So why did Japanese swordsmen feel the need to bend the katana blade? Bending offers several advantages, one of which is the purification of the metal. The iron sand, steel, and other metals used to create traditional Japanese swords were not devoid of impurities. Rather, they contained small, minute amounts of other metals and minerals. And when left unchecked, these impurities detracted from the blade quality of the swords. To avoid this, Japanese swordsmen bent the blade several times – up to 30 times – in order to purify the blade.

Folding also compressed the metal, making it stronger. Each time a blade was bent, it gained strength. Over time, this forging tactic could transform an otherwise weak and brittle blade into an unbreakable one, perfect for the katana.

Today, Japanese swordsmen continue to make the katana and other traditional swords by bending the blade. This is one of the reasons why traditional Japanese swords are prized by collectors and practitioners of martial arts. And while there are new manufacturing methods, like factory machines, they don’t offer the same level of quality as traditional Japanese craftsmanship tactics, like blade bending.

Japanese black sword

Why and how to oil your swords

Whether you own a katana, tachi, wakizashi, tanto, or any other sword, you need to maintain the blade properly. Swords require very little maintenance to maintain their appearance and structural integrity. However, an essential step in the maintenance of swords is oiling. Applying oil to the blade of your sword will protect it from damage and extend its life.

Benefits of Oiling Your Sabers

The primary purpose of oiling the blade of a sword is to protect it from rust and corrosion. Regardless of type, all swords are susceptible to rust. This natural phenomenon occurs when oxygen molecules reach the ferrous metals inside the blade of a sword, triggering oxidation and subsequently causing rust.

I know what you’re probably thinking: my sword isn’t made of iron, so it won’t rust. Well, the truth is that all swords have at least some iron content in the blade. Whether it’s bronze, stainless steel, or high carbon steel, iron is present in virtually every metal used to make swords. It is true that stainless steel has a lower concentration of iron than high carbon steel, but the fact is that all swords contain iron. Therefore, they can all rust.

By coating the blade of your sword with oil, you will create a protective barrier between the ferrous metals and the outside elements. Rusting usually occurs when water vapor in the air – which contains oxygen molecules – reaches the blade of the sword. If the blade is coated with oil, water vapor will not be able to reach the blade, which will protect it against rust and corrosion.

Choose the right oil

There are special oil products made especially for swords, some of which are sold in cleaning kits. However, most of these products contain the same basic ingredient: mineral oil. Mineral oil is a safe and effective solution to protect your swords against rust and corrosion.

You can also use choji oil, which is often recommended for traditional Japanese swords. That said, choji oil is actually made up of mostly mineral oil with a small amount of clove oil. Clove oil has no function, it just adds a nice smell to the sword when finished.

Application of oil

To apply the oil, place a small amount of product on a lint-free microfiber cloth and carefully rub the surface of your sword’s blade, being very careful not to accidentally cut yourself. You want to apply a generous coat of oil, making sure the entire blade is covered. When you’re done, carefully store your sword.


Regardless of your level of martial arts activity, your katana will likely spend most of the time on display – and that’s okay. A high-quality katana serves as a focal point, sparking conversation with anyone who sees it. But there are some things you need to know about exposing a katana.


There are dozens of different display cases and stands you can place your katana in. One of the most popular, however, is katanakake. The katanakake is basically a wooden rack with pairs of hooks, designed to hold one or two swords. In feudal Japan, samurai warriors placed their swords on the katanakake before entering buildings, although this type of katanakake features a slightly different design.

Sharp edge up

Traditionally, Japanese swords like the katana are presented the same way they are carried. As the katana is worn with the edge up, it must also be presented with the edge up.

Some people think that exposing swords with the edge up helps protect the blade from damage, but that’s not necessarily true. Displaying the katana with the edge up is a way to “respect” the sword. It dates back hundreds of years to feudal Japan, where it was the standard way to display katanas. Since then, the tradition remains, with martial artists and sword collectors continuing to display their katanas in this manner.

Tsuka left or right?

Functionally, displaying your katana with the tsuka left or right makes no difference. You can display your katana with the tsuka on either side without fear of it adversely affecting the blade or other elements.

That said, traditional Japanese etiquette is that displaying the katana with the tsuka on the left signals peace, while displaying the katana with the tsuka on the right signals the will and ability to fight. Assuming you display your katana in your home, either way is perfectly acceptable. However, if you are exhibiting it in a dojo, you should ask your sensei for a recommendation.

However you display your katana, it is important to clean, polish and oil it regularly. Over time, dust, debris, and moisture will settle on the blade, which can lead to rust. However, by cleaning and oiling your katana, you can protect it from such damage.

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