oilstone

An oilstone is a sharpening stone that uses oil as a lubricant between the blade and the abrasive surface. It is used to sharpen and hone edges on knives, chisels, plane irons, and other cutting tools. Oilstones can be natural stones, such as Arkansas stones, or synthetic stones made with aluminum oxide or similar abrasives.

Natural Arkansas stones are quarried novaculite and come in soft, hard, and translucent varieties. They are valued for a fine, smooth cut and their ability to produce very sharp edges with careful use. Synthetic oilstones rely on a hard abrasive substrate bound in resin and are produced in a wide range of grits, from coarse to fine, to suit rough stock removal or premium honing.

Oil is used as a lubricant and coolant, carried into the cut by the stone and the blade. A light coat of honing oil or mineral oil is applied before sharpening. The blade is drawn across the stone at a consistent angle, with even pressure. For repairs and reestablishing a bevel, a coarse oilstone is used; for honing, a fine or extra-fine stone follows.

Maintenance includes keeping the stone flat, removing swarf, and occasionally flattening the surface with a lapping plate or coarse grit. After use, wipe away oil and metal particles and store in a dry place. Advantages of oilstones include effective lubrication, long life, and suitability for a variety of steel types; limitations include slower cutting and the need to manage oil and swarf, compared with water stones.

Oilstones have a long history in metalworking and woodworking and remain popular among traditional tool users for their control and edge retention, especially on chisels, plane blades, and straight razors.