±â¸§¼ýµ¹(Oilstone)

whetstone: natural or manufactured stone used as an abrasive solid to sharpen tools. It is used dry, with water, or with oil. Such a stone of the finer grade used with oil is usually called an oilstone.

Natural Arkansas Whetstones are available in four grades. Users should be aware that color is not the determining factor in grading Novaculite.
Some users have been defining whetstone grades by color, but the same colors may be seen in more than one grade. Color in the stones is caused by trace minerals that dispersed through the rock during the sedimentary formation more than 300 million years ago and subsequent geologic activity. Novaculite is 99.9% pure silica.
Different grades of Novaculite also have a noticeable difference in texture. The softer the stone, the coarser the surface of the stone feels; harder stones have a smoother, even glassy with True Hard and Translucent, feel.
The texture of the finished stone surface may vary from the natural texture of the stone because the stones are produced using fine grit to lap, or finish, the stone. With use, users may notice a slight change as they get through the surface finish and reach the true abrasive quality of the stone.
Soft Arkansas is the most popular of the four grades of Novaculite. It is an all-purpose stone used by wood carvers, sportsmen, butchers, commercial knife sharpeners and even housewives who desire keen, polished edges on knives and tools in a minimum of time. Soft Arkansas stones may be white, gray and black, and pink and gray in color.
Hard Arkansas is most suitable for fine polishing and maintenance of a fine edge on knives or tools. Hard Arkansas is often referred to as White Hard; users should be aware that Hard Arkansas often has color variations, too. This color does not interfere with the honing process by any means. Hard Arkansas stones are popular among woodcrafters and a variety of industries including the dental industry.
True Hard Arkansas is the finest grade abrasive available today. Most commonly used for industrial applications where an extremely fine polish is required. True Hard Arkansas stones are often refered to as Multi-colored Translucent; colors, both opaque and translucent, are random and may include black, red, white, and gray--often within the same stone.
Black and Translucent Arkansas stones are included in the True Hard category according to the Specific Gravity. Black Arkansas stones are black or blue-black in color. Translucent stones may be a uniform, translucent shade of gray , white, yellow, brown and sometimes even pink. True Hard, Black and Translucent stones are available in all published sizes and shapes.