Most knife-sharpening instructions only cover smooth-edged knives like chef’s and paring. Serrated knives don’t require as much maintenance as those other knives, but they do dull after a while. How do you sharpen them?
Since serrated blades have points and valleys, the key to sharpening them is reaching the valleys, since they make up the majority of the blade’s edge. That two-level design also explains why serrated knives don’t have to be sharpened as often as smooth blades: Because their pointed teeth do most of the work and the finer scallop-shaped serrations follow the points through the food, the edges endure less friction and degrade more slowly.