【Reading】あらといし

【English Name】Coarse Whetstone

The arato (coarse whetstone) is the coarsest-grit type of whetstone, with a grit number of roughly #80 to #600, typically around #200. It has high cutting power and is used to repair chips in a knife edge or to reshape the blade.

Whetstones are generally divided into three stages—coarse (arato), medium (nakato), and finishing (shiageto)—and the arato handles the first of these steps. Because medium and finishing stones alone lack the power to correct an edge that has rounded over with long use, the role of the arato is considered significant.

Most stones in circulation today are synthetic whetstones (such as ceramic stones), characterized by uniform quality and stable abrasive power. Natural arato, on the other hand, are said to have been used since before the Jomon period, and shaped sandstone has been excavated even from Yayoi-period tombs. In the early Meiji era, more than 100 brands were produced nationwide, but due to the difficulty of mining, the decline of high-quality quarries, and the spread of synthetic stones, natural ones have become rare.

For chefs, including sushi chefs, a knife's sharpness is fundamental to the work. The arato is not used daily, but when serious damage occurs to the edge it is an indispensable tool, serving as the starting point of the basic sharpening process that progressively finishes the edge in combination with medium and finishing stones.