Almost every case of a rusty blade or a darkened handle comes down to how the knife is washed, and what happens after washing. On this page, Hayashi Hardware, a knife shop founded in 1872, walks you through everyday washing, washing after sharpening, what not to do, and what to watch for with each material.
Washing After Use: 3 Steps
- Wash right away: Don't leave the knife sitting after use. Wash it under running water with mild dish detergent and a soft sponge. Hold the sponge from the spine (the side opposite the edge) and move it in one direction along the blade
- Dry right away: With a clean, dry cloth, wipe all the moisture off the blade, the handle and the ferrule (where the blade meets the handle)
- Let it air-dry before putting it away: Leave it for a while somewhere well ventilated, then store it
After cutting acidic foods such as citrus, tomatoes or ume plums, or anything salty, be especially sure to wash the knife right away.
Washing After Sharpening
After sharpening on a whetstone, the blade is coated with sharpening slurry, a mix of stone particles and metal filings. If you use the knife as it is, the slurry will end up in your food, so always wash it off.
- Rinse off the slurry under running water. If a thin lip of metal (a burr) remains on the edge, remove it gently with a finishing stone or newspaper
- Wash with mild detergent and a soft sponge. A freshly sharpened edge is very sharp, so never press the sponge straight into the edge
- Wipe it dry and let it air-dry. Carbon-steel knives are most prone to rust right after sharpening, so take care not to miss any spots
Washing Mistakes to Avoid
| Don't | What happens |
|---|---|
| Soak the knife or leave it wet | Rust, a darkened or cracked handle, a loose ferrule |
| Use a dishwasher | Heat and detergent crack the handle and damage the blade too. Not suitable for wooden handles, black fluorine coatings or carbon steel |
| Use steel wool or abrasive cleanser | Scratches the blade. Especially visible on black fluorine coatings and mirror finishes |
| Soak it in bleach | Corrosion and discoloration of the blade |
| Pour boiling water over it and leave it | The sudden temperature change and moisture cause rust and handle deterioration |
| Put it in the sink with other dishes | Chipped edges and injuries |
Notes by Material
- Stainless steel (AUS-8, VG-10, etc.): The basic 3 steps are enough. If left wet overnight, it may develop small rust spots
- Carbon steel (hagane, Aogami, etc.): Wipe it dry right after washing. Apply a thin coat of camellia oil before long-term storage
- Black fluorine coating (Kurokage, etc.): Cleansers and steel wool damage the coating. Use a soft sponge
- Wooden handles (Ho wood, Wenge, Ebony, etc.): Wipe the handle dry too. Once a month, a thin coat of food-safe drying oil helps prevent cracks and darkening
After Cutting Meat or Fish
Fat and salt tend to linger, so wash with lukewarm water and mild detergent. Along with the cutting board, wash all the way to where the blade meets the handle. If odor bothers you, wiping the knife with a dry cloth after washing and letting it dry somewhere well ventilated is enough. Sanitizing with boiling water is fine as long as you wipe the knife dry right away.
Drying and Storage
- After wiping, stand the knife up or put it in a knife block to dry. Keep the blade from touching other metal
- If you keep it in a drawer, fit a blade guard (saya)
- If you won't use it for a month or more, dry it completely, apply a thin coat of camellia oil to the blade and wrap it in newspaper
If Rust Appears
For light spots of rust, put a little cream cleanser on a cloth and rub along the length of the blade (not on knives with a black fluorine coating). For deep rust or chips, don't force it; send the knife in for resharpening. For details, see "What to do if your knife rusts" in our Complete Knife Care Guide.
Frequently Asked Questions
Q. Can I put my knife in the dishwasher?
Not if it has a wooden handle. Heat and detergent crack the handle and damage the blade too. All the knives we carry should be washed by hand.
Q. Do I need to oil the knife after washing?
Not for stainless knives. For carbon-steel knives in daily use, wiping them dry is enough; apply camellia oil only for long-term storage.
Q. Can I use the knife right after sharpening?
Yes. Once you have rinsed off the slurry and wiped it dry, it is ready to use.
Q. What detergent should I use?
Ordinary mild kitchen dish detergent is fine. Avoid detergents containing abrasives, and avoid bleach.
Our Resharpening Service
For knives bought from us, the first resharpening is free (from ¥1,500 per knife after that; mail-in available within Japan). When your knife starts to lose its edge, try our resharpening service.