India sharpening stones are manufactured using a proprietary process that impregnates them with a petroleum-based product that allows the lubrication used during the sharpening process to stay on the stone’s surface. As a result, the metal from the object being sharpened and small pieces of abrasive that break off the stone become suspended in the lubricant. This prevents these materials from imbedding into the sharpening stone’s surface, keeping it free-cutting and easy to clean.