Although kurouchi knives do not resist oxidation as well as stainless knives, any discoloration will not affect performance. If you do not like the patina that your knife develops, then it can be removed by sharpening. Kurouchi knives should be treated with the same respect as other high-performance kitchen cutlery — dried after every use and stored safely so it does not bump into anything. If there is going to be a long time between uses then we recommend using non-toxic oil on the knife to prevent rust. Cooking oils are a good choice since they are safe to consume.