Date of this Version
A hardness tester, especially adapted for grain, was constructed by modifying a commercial portable soft metal tester known as the Barcol Impressor. A preloaded stylus is forced into grain sections prepared by means of a microtome. The displacement of the stylus, measured by a dial micrometer, is used as a hardness index. This has been related to the Vickers diamond pyramid hardness which is a standard metallurgical test. A number of hardness measurements may be made on a single transverse kernel section. The tester may be used for all wheat varieties. Significant variations in hardness within a single wheat kernel section have been demonstrated. While the hardness of a block of lead varied over ±½ hardness lumber, a kernel section of hard winter (Ponca) wheat exhibited hardness numbers ranging from 25 to 40, on the arbitrary scale of this tester.