an area approximately 1 in. (25 mm) in diameter shall be marked with a 950℉(510℃) temperature-indicating crayon or paint. The marked area shall be heated with a blowtorch, a Bunsen burner, or similar device to a temperature between 950℉(510℃) and 975℉(524℃). The specimen shall then be immediately quenched in cold water, which produces a network of fine cracks on each face.