Although your serrated knives will still cut as they grow dull, you will begin to notice a tearing or shredding action rather than smooth cuts. If this is happening, then it is time to sharpen your knife. Sharpening dull serrated blades can be a bit more difficult than sharpening plain blades. Maintaining serrations is important if you want your knife to cut well, but they do require a bit more experience to sharpen. Serrated blades can also take longer to sharpen than a similarly sized plain blade.
The good news is that because of the design of a serrated edge, the serrations actually take longer to become dull than a plain edge, even on the same knife. The sharp points on the serrations start the cut, and the curved parts between these points are relatively protected, experiencing less pressure, which keeps them sharper for a longer period.
To sharpen serrated blades you’ll need to find the right knife sharpener. Look for a sharpener that is specifically designed to be used with serrated blades. They may come in the form of a pull-through sharpener, a sharpening stick, or a sharpening stone. What makes them different than regular knife sharpeners is that they have a small “V” shaped cross-section that can be worked inside each serrated tooth. Some of the serrated knife hones are triangular in their shape in order to accommodate the serrations, and they can be tapered to accommodate many differently sized serrations. The same principles apply to choosing a serrated knife sharpener as choosing a regular knife sharpener, including materials and sharpener styles.
Some of these sharpeners can be used both for plain blades and for serrated ones. Gut hooks and fishhooks, found on some knives designed for hunting or other outdoor uses, can be sharpened using this type of sharpener. Pocket-sized serrated knife sharpeners are perfect if you carry a pocketknife with a serrated blade section.
When using the knife sharpener on a serrated blade, regardless of what type of sharpener you choose, keep the angle in mind. On a knife with a partially serrated blade, the serrations are nearly always ground at the same angle as the plain edge portion of the same blade. When sharpening the serrated edge, it should be kept at this same angle to give it as close to the original factory edge as possible. Some styles of knife sharpeners have a system for holding the knife at a specified angle so that you can be sure each of the teeth is sharpened at the angle you choose.
When sharpening serrated knives, you can’t just draw the knife across a sharpening stone like a plain knife blade. To sharpen the serrations, work the hone perpendicular to the cutting edge of each serration. A serrated knife should be sharpened one tooth at a time, which can be time consuming. Only move on to the next tooth when you can see or feel a raised burr of metal. Then flip the knife over, and lightly grind the burr off from the backside of the knife.
Although it can take patience to sharpen serrated blades, the actual process is not that difficult. Don’t let fear of the process scare you away from sharpening the serrated knives. As long as you have the right sharpener, specifically one that is designed for serrated blades, it is possible to return your serrated knives to close to their original sharpness.