There are countless ways of testing knives and tools for sharpness. We believe the easiest way to test sharpness is to use the tool or knife. If it doesn’t cut fast and cleanly, it needs sharpening. On a kitchen knife, the knife should be able to cut vegetables with almost no downward pressure. On a woodworking tool, the tool should cut wood fibers cleanly without leaving marks or crushing the wood fibers. On a fillet or skinning knife, it should be able to cut very quickly without having to saw through the meat.