Knife handle materials need special attention and care. Do not allow kitchen knives to soak at the bottom of a sink full of water and dirty dishes as it will destroy the surface texture. Automatic dishwashers are not good for knives as the temperature in the machines are too high and this will affect the steel as well as organic handle material like wood, bone, ivory, horn etc. Natural wood handles need to be tended carefully with polish and cleaning regularly. As most of the wood used for handles has been treated with tung oil and coated many times until it developed a nice sheen, the best way to preserve the wood is to restore the finish with an occasional coat of tung oil and wiping it with a clean, dry cloth. It will be good to let the knife dry overnight and buff it with another clean dry cloth before using it. It is not a good idea to soak knifes with natural handles in hot soapy water. Micarta and other artificial material that are impervious to moisture can be soaked thus, but natural material will be affected by such a practice.