Guide to Katana Maintenance

Katanas are exquisite weapons that demand meticulous care to maintain their beauty and functionality. Whether you are a collector or a practitioner, understanding how to clean and maintain your katana properly is essential. This guide combines general maintenance tips with specific cleaning procedures to ensure your katana remains in pristine condition.

How to Clean a Katana?

Regular Cleaning

Frequency:

• If in storage: Clean every few months.
• If handled regularly: Clean after every use.

Tools Needed:

• Uchiko ball (filled with finely ground stone powder)
• Sword oil (choji oil, typically a type of mineral oil)
• Clean, soft cloth (silk or microfiber)
• Rice paper or high-quality tissue paper
• Cotton pads or swabs
• Mekugi-nuki (bamboo or brass hammer for removing the mekugi)

Disassembly

1. Remove the mekugi using the mekugi-nuki.
2. Carefully slide the handle (tsuka) off the tang (nakago).

Cleaning the Blade

1. Removing Old Oil:
   • Use a clean cloth to wipe off any old oil from the blade.
2. Applying Uchiko Powder:
   • Gently tap the uchiko ball along the blade to apply a thin layer of powder. This helps absorb any remaining oil and moisture.
3. Wiping Down the Blade:
   • Use rice paper or high-quality tissue paper to wipe off the uchiko powder, drawing from the back of the blade to the tip.
4. Oiling the Blade:
   • Apply a small amount of sword oil to a clean cloth or cotton pad and gently spread it over the entire blade, ensuring a thin, even coat.

Cleaning the Tang (Nakago)

• Wipe the nakago with a dry cloth. Do not oil the nakago, as oil can cause the wood of the tsuka to deteriorate over time.

Reassembly

1. Carefully slide the tsuka back onto the nakago.
2. Replace the mekugi, ensuring it is securely in place.

Storing the Katana

Environment:

• Store the katana in a dry, cool place away from direct sunlight and moisture. Excessive humidity can cause rust, while excessive dryness can cause the wooden parts to crack.
• Avoid storing the katana in a basement or attic, as these areas often have fluctuating temperatures and humidity levels. 

Position:

• Ideally, store the katana horizontally with the edge (ha) facing upwards to prevent the edge from resting on the scabbard (saya) and causing potential damage.
• If displayed vertically, ensure the katana is in a kake (sword stand) designed to support the blade properly.

Scabbard (Saya) Care

• Ensure the inside of the saya is clean and free from debris. Occasionally clean it by using a saya-nuki (a small piece of cloth attached to a rod) to remove any dust or particles.
• If the saya becomes too loose or too tight, have it adjusted by a professional to ensure a proper fit.

Additional Tips

Handling:

• Always handle the katana with clean hands to avoid transferring oils and sweat to the blade. Consider wearing gloves if you need to handle it frequently.

Inspection:

• Regularly inspect the katana for any signs of rust, corrosion, or damage. Early detection can prevent more significant issues.

Professional Maintenance:

• Periodically have your katana professionally inspected and maintained, especially if you notice any issues beyond regular cleaning and care.

General Maintenance

Material Considerations:

• Katanas are made from materials that rust. Titanium covered katanas are rust resisting. Rusting is an oxidation reaction of steel and can be prevented by keeping the katana away from air and moisture.

Preventive Methods:

• Apply mineral oil to the steel surface, forming an oil film that isolates the air and prevents rust and oxidation.

Preparation Before Oiling:

• Use a dry, soft towel to thoroughly clean the steel surface, removing any stains and moisture. Rubbing for more than three minutes is ideal.

Oiling Frequency:

• Apply oil every 24 hours to ensure the katana is covered. If displaying the katana, you can wipe off the oil temporarily, but reapply oil before storing it in the scabbard. In dry regions, apply oil once a month; in humid regions, apply oil every half month.

Long-term Storage:

• For long-term storage, apply a thick layer of oil and wrap the blade in dry plastic wrap to seal it. Store the blade and scabbard separately. Always wear gloves during this process. If done correctly, the katana can be stored for over six months.

Avoid Rust-Causing Practices:

• Never touch the blade with your fingers, breathe on it, or let it come into contact with body fluids or plant sap. After using the katana for cutting, clean it promptly to prevent rust. For stubborn black spots or stains, use rust removal paste with an old towel.

Rust Removal

Signs of Rust:

• Rust appears as small black spots or brown patches. Regularly inspect the katana for rust and remove it promptly using rust removal paste and an old towel.

For Traditional Katanas:

• If a traditionally polished katana with multi-layer polishing (e.g., “three-color/polishing” or “thirteen-layer polishing”) rusts, removing the rust with paste will turn the polished surface into a mirror finish, ruining the handcrafted effect.

Protective Method:

• Use masking tape to cover non-rusted areas, exposing only the rust spots. Apply and rub the rust removal paste vigorously until the rust is gone. After removing the tape, clean the entire blade with oil and a towel. This minimizes the mirror finish area caused by the paste.

Required Supplies:

• Rust Removal Paste
• Mineral Oil
• Cleaning Cloth (old towels or soft fabrics). Paper towels can be used if layered thickly to avoid cutting your hands.

Note:

• Choji Oil consists of 99% mineral oil and 1% clove oil that gives it a distinctive scent.

Important Handling Instructions

1. Safety Handling:
   • Always keep the katana handle up to prevent the blade from slipping out of the scabbard. Avoid direct contact with the blade, breathing on it, and ensure it is always clean and dry.
2. Storage Conditions:
   • Do not expose the katana to sunlight or humidity. Handle it gently to avoid impacts and scratches.
3. Drawing and Sheathing:
   • Do this slowly and gently, using the back of the blade to touch the scabbard to avoid scratching the edge.

Using Performance Katanas

Practicing:

• Incorrect swinging can damage the blade edge or tip.

Blade Edge:

• The blade tip is thin and has low strength. Avoid stabbing or hitting hard objects.

Traditional Katanas

Avoid Cutting Tests:

• Any cutting tests will scratch and damage the polished edge. Traditional katanas with delicate finishes should be handled with extreme care. If rust develops, the entire katana will need expensive re-polishing.

Handling:

• Use only soft towels to handle the blade. When placing it on a table, use a cloth or paper towel to avoid scratches.

By following these detailed instructions, you can ensure that your katana remains in excellent condition, preserving both its aesthetic beauty and functional integrity for years to come. Regular maintenance and careful handling are key to the longevity of this remarkable weapon.