In case the point hasn’t been made strongly enough already, a sharp edge really is the backbone of whittling. Each cut made using your pocket knife will result in the gradual dulling of its blade. Therefore it is necessary to keep a close check on the maintenance of the knife-edge to ensure that it is performing exactly as it should. The simplest (and most pocketable) sharpening tool is a ‘whetstone’. Whetstones can be purchased from numerous high street outlets and online retailers. Ranging in size from 4–20cm (1½–8in), pocket knife whetstones are formed of two contrasting sides: a coarse, rough surface (for sharpening) and a smoother, finely graded surface (for ‘finishing’).
To sharpen your knife, either place the whetstone on a tabletop with the rough surface uppermost, or hold the stone in the palm of your hand with fingers and thumb kept below the top surface of the stone.
Lie your blade on the stone’s rough surface, set at a 30-degree angle (see fig. 1). Draw the blade across the stone first on one side, then turn the blade over and repeat on the other side. The knife-edge should be facing away when being drawn inwardly towards the handler. Repeat this action until the knife feels sharp; check by lightly running your thumb or fingers across the blade from left to right, taking care not to follow the line of the blade.
Turning the whetstone over, use the smoother side in much the same way in order to provide a smooth finish (see fig. 2). Afterwards, wipe the knife using a damp or lightly oiled cloth.
When working with a folding knife, such as a penknife or Swiss Army knife, it is important also to maintain and clean the body of the knife. With frequent use, dust and debris often collects within the handle into which the blade is folded. If left unchecked, remnants like these can cause damage to the blade itself. Knives of this type require a light oiling from time to time in order to lubricate the folding mechanism. Regular 3-in-1 oil is a good choice for this purpose.