The Norton Crystolon 100/280-grit combination oilstone is made of silicon carbide with 100 grit on one face for repairing cutting edges and 280 grit on the opposite face for sharpening and maintaining them; it sharpens to moderate tolerances with minimal loading when it is more important to sharpen the blade quickly than to produce a fine cutting edge. This oilstone is used to restore cutting edges on straight-edged tools, such as chisels, knives, plane blades, and precision instruments. The stone is prefilled with oil to save time and eliminate the need to presoak it prior to use. The oil prevents metal from bonding with the abrasive surface by flushing away dislodged abrasive and metal chips. This silicon carbide stone is fast cutting, and offers effective sharpening, even under light pressure. It is created by grading silicon carbide to a consistent particle size and blending it with bonding agents. It is then molded and surface-finished. This 1 x 8 x 2 inch (H x W x D) stone, suitable for bench use, is harder and more durable than a waterstone. (H is height, the vertical distance from lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back.) It conforms to the American National Standards Institute (ANSI) abrasive grit standards. Sharpening stones, or whetstones, are abrasive surfaces used to sharpen and hone the edges of steel cutting implements, such as chisels, knives, scissors, hand scrapers, and plane blades. Sharpening is the process of creating or re-establishing a cutting edge by grinding away portions of the metal to adjust the angle of the edge and reform the shape. Honing removes small imperfections. Stones can be flat, for working flat edges, or shaped, for edges that are more complex. Sharpening stones are made of natural or synthetic materials that range from softer to harder, and are categorized by the size of their abrasive particles, known as grit. A stone with a coarser grit is used when more metal needs to be removed (e.g., when sharpening a nicked or very dull blade); the stone with the finest grit produces the sharpest edge. Where numbers are assigned to specify grit, they range from coarser grit (low) to finer grit (high). Some sharpening stones are designed for use with a lubricating liquid, some can be used dry, and others can be used either wet or dry. When used with lubricating liquid, a sharpening stone can be called a waterstone or an oilstone, based on the lubricant required. Norton Abrasives manufactures sanding, grinding, and polishing abrasives, and has been located in the United States since 1885. Norton, now a brand of Saint-Gobain, meets ISO 9000 and 14001 certification for quality and environmental management standards.