Sharpening Your Knives with a Stone
Knives are often sharpened by grinding against a sharpening stone. The smaller the angle between the blade and stone, the sharper the knife will be, but the faster it will dull. Very sharp knives sharpen at 12-15 degrees. Typical knives sharpen at 22 degrees. Knives that chop may sharpen at 25 degrees. In short, the harder the material to be cut the higher the angle of the edge. The composition of the stone affects the sharpness of the blade (finer grain produces sharper blades), as does the composition of the blade (some metals take/keep an edge better than others).
Once sharpened on the stone, you need to remove a wire edge (burr) if one forms during sharpening. Use a slightly steeper angle with very light pressure to do so. If not removed, it will break off in use, and the knife will instantly become dull.
Traditional stones are Arkansas stones, which come in soft (coarse) and hard (fine) varieties. However, the more common stone is less expensive India stone which is very similar in function and end result as the Arkansas stone. These are traditionally used with water or honing oil.
Oil is used to lift the metal dust, called swarf, off the stone. This is usually recommended for natural stones, but some say that detergent and a brillo pad will have the same effect. Diamond stones should NOT be used with oil. They can be washed off with water.
Stropping a knife is an excellent finishing step. This is traditionally done with a leather strap impregnated with abrasive compounds, but can be done on paper, cardstock, or even cloth in a pinch. It will not cut the edge significantly, but produces a very sharp edge with very little metal loss. It is useful when a knife is still sharp, but has lost that 'scary sharp' edge from use.