HOW TO
Clean a Japanese Knife
Without Damaging It
A well-made Japanese knife will serve you for years—if you take care of it properly. One of the most crucial aspects of Japanese knife care is washing it correctly. Unlike stainless steel kitchen knives, high-carbon steel blades require extra attention to prevent rust and maintain sharpness. Follow these simple steps to keep your knife clean, rust-free, and always razor-sharp.
Step-by-Step Cleaning Guide
1. Rinse the knife with warm water.
This helps loosen any food particles and prepares the blade for proper cleaning.
2. Apply dish detergent to a wet sponge.
Use a mild detergent—nothing too harsh. Your knife needs cleaning, not a chemical bath.
3. Support the blade with a stable base.
When cleaning, it’s best to rest the blade on a secure surface to avoid slipping or unnecessary flexing.
4. Scrub the blade using the soft side of the sponge.
Pay close attention to both sides of the blade, the spine, and the junction between the blade and handle—an often-overlooked spot that deserves extra care.
5. Don’t forget the handle.
Give it a good scrub along its length, at the junction with the blade, and the end. Whether it’s wood or synthetic, a clean handle means a clean grip.
6. Rinse thoroughly with warm water.
Cold water is a knife’s worst enemy! (More on that below.)
7. Dry immediately.
Wipe the blade with a dry cloth, ensuring no moisture remains. Give the handle a good squeeze to remove excess water, especially if it's wooden.
Why You Should Never Wash a Japanese Knife with Cold Water
Warm water is used to heat the blade to ensure better evaporation of any micro-pockets of water on the blade. Cold water cannot effectively wash away grease and other food residues, and a blade washed with cold water retains a greater amount of micro-moisture, which can lead to bacterial growth and even rust.
Did you know? Hot water cannot destroy the blade, as it takes a minimum of 160°C to loosen the HRC hardness of the knife, let alone destroy the blade. Your hands will not withstand such high temperatures that damage could occur, but we hope you don't forget your steel pet in the oven. ;)
Knife Cleaning Practices for Professional Chefs
In high-level culinary environments—especially in Japanese cuisine—knife cleanliness is treated with the same precision as knife sharpness. For chefs working in open kitchens or preparing delicate raw foods like sushi, a knife must appear not only clean but immaculately maintained, free of any visible oxidation, staining, or patina.
To achieve this, many professionals use a rust eraser—a high-abrasion rubber compound designed to remove rust, food residues, and surface stains from carbon steel blades. When used thoroughly, a rust eraser can strip away grime, discoloration, patina, and even traditional kuro-uchi finishes. This process will inevitably leave fine scratch marks on the blade surface, particularly on softer cladding or dark-forged finishes.
Why accept the cosmetic trade-off?
In traditional Japanese kitchens, especially among sushi chefs, any sign of patina or oxidation is considered unacceptable, both for hygienic and aesthetic reasons. The knife is a visible tool—often used in front of guests—and it must reflect the same level of care and cleanliness as the chef's workspace. In this context, patina is not seen as a protective layer, but as a blemish. The blade must look and feel sterile, polished, and pristine at all times.
While this approach may not be suitable for every kitchen or every type of knife, it remains a standard among chefs who demand absolute cleanliness and visual perfection from their tools—even at the expense of surface finishes.
Here’s how to clean your knife after a long, hard day in the (pro) kitchen
Cleaning Knives for Professional Chefs
Note: For maximum cleanliness, professionals often use a rust eraser to remove all grime, rust, and patina. While highly effective, this method leaves scratch marks and can strip finishes like patina or kuro-uchi.
1. Rinse the knife with warm water.
2. Provide the blade of the knife an additional, higher surface for added stability.
3. Pour some dish soap on the blade.
4. Use a rust eraser to spread it over the blade and rub to remove any spots.
5. Don’t forget to do the same to the spine, the heel and the machi of the blade.
6. Apply dishs soap to a sponge and scrub the blade vigorously - on both sides, the spine, and the junction between the blade and the handle (this spot needs extra attention).
7. Scrub the entire handle—along its length, at the junction with the blade and its end.
8. Rinse off the foam with warm water (cold water is a knife’s enemy!)
9. Wipe the blade dry.
10. “Wring out” the handle.
For pro chefs, a spotless blade isn't just about hygiene—it reflects their professionalism, discipline, and respect for the craft. A clean knife is one of the first signs of a clean kitchen and a conscientious chef. This level of cleaning is standard among elite chefs who demand not only peak performance from their tools but also flawless presentation.
FAQs: Japanese Knife Cleaning & Care
Absolutely not! The heat, detergent, and water pressure can damage the blade, dull the edge, and warp wooden handles. Always hand-wash your knife.
Every time you use it! Never leave your knife dirty, especially if you’ve been cutting acidic foods like citrus, tomatoes, or onions.
No—soaking can lead to rust and handle damage. Wash it quickly and dry it immediately.
Use a rust eraser to gently remove rust spots. Regular oiling (especially for high-carbon steel knives) helps prevent future rusting.
The patina is a thin protective layer that forms on oxidized steel, preventing further oxidation. Rust, however, is a thicker, corrosive layer that accelerates deterioration. If you notice rust on the blade, you should remove it before using the knife.
Store it in a knife block, on a magnetic strip, or in a protective saya (wooden sheath). Avoid tossing it in a drawer where it can get damaged.
Final Thoughts
Keep Your Japanese Knife in Top Shape
Proper Japanese knife maintenance isn’t complicated, but it does require attention to detail. By washing, drying, and storing your knife correctly, you’ll ensure it stays sharp, rust-free, and ready for action for years to come.
Taking a few extra seconds to wash your knife properly will keep it in peak condition for years to come. Treat it well, and it will return the favor every time you step into the kitchen.
Looking for more tips on Japanese knives? Explore our guides on How to sharpen your Japanese knife and the Maintenance of kitchen knives for expert advice!
