Rust is never covered by warranty, but you can prevent it. And if your knife does rust, you can usually remove it easily yourself.
How does my knife get rusty?
Any knife can rust, even one made from stainless steel. Moisture, acid and salt, such as sea air or fruit acid, are almost always the cause. There are a few types of rust:
- Surface rust: small spots on the surface. It can form in the dishwasher, for example, when your knife is washed alongside rusty cutlery or a rusty pan. The rust effectively travels through the dishwasher and settles on your knife.
- Pitting corrosion: a rust spot around a small pit. Around 15% chromium gives stainless steel a protective layer of chromium oxide. This prevents it from rusting at humidity levels up to 70%. If the layer is damaged, a new one normally forms. But a small area of damage combined with a drop of water can cause pitting corrosion.
- Patina: steel with a high carbon content (carbon steel) is very hard, but not stainless. A knife made from it discolours quickly, especially when exposed to fruit acid. Think of knives by Robert Herder, Opinel and Eden Kanso Aogami. This discolouration is called patina and is nothing to worry about: over time, it even makes your knife a little less prone to rust.
How do you prevent rust?
Wash your knife by hand after use and dry it straight away. Keep it away from fruit acid and salt, including sweat, and store it somewhere dry. Add a drop of oil to the blade and handle now and then, and the chance of rust will be very small.
How do you remove rust from your knife?
Rub the rust away with the Naniwa Rust Eraser or an ordinary eraser. Be careful: the eraser also polishes the metal, so it may leave small scratches or a dull patch.
You can also polish away the rust with a cloth and a little Flitz polishing paste.
We do not recommend home remedies such as vinegar, lemon juice, cola or leaving the knife in an onion or potato overnight.
Not working?
Send us a photo of your knife through the contact form and we'll help you find a solution. For more about what is and is not covered by warranty, read Warranty explained.