It is very essential to have a good oil-stone. They can be found of many degrees of fineness. Those of very fine and hard grain, which give a keen edge but cut very slowly, will not be found so well adapted to your use as those of moderate coarseness and softness, which cut faster. The stone known as Red Washita is good to use for wood-working tools, as it cuts rapidly. It should be free from hard spots. The Arkansas stone produces a very fine edge, but is of so fine texture that it is not so well adapted for your tools as a coarser stone, unless you happen to find a quick-cutting one. The Turkey stone will produce a keen edge, but is not so good for your use.

Some stones (and excellent ones) cut best with water. When first trying a new stone use water, and if the surface does not become at all glazed or polished it will not be necessary for you to use oil.

The stone should always be kept covered when not in use, to protect it from the dust and dirt. Set it in a block with a cover or make a box for it. Always wipe it clean after using, to remove the paste of ground stone, steel, and oil left on the surface.

When an oil-stone becomes unevenly worn, it can be trued by rubbing it around on a sheet of sandpaper fastened on a fiat surface, like the side of a board. Water can be used in this operation.

In addition to the ordinary flat oil-stone, slips of stone of various shapes are useful, a common and useful form being that shown in Fig. 612, wedge-shaped on one edge and convex on the other. If you have V-tools, carving gouges, or other tools sharpened on the inside, you must have slips of stone of various shapes with which to sharpen them. See Oil and Sharpening.