(a) All grapes in the sample shall be completely crushed without unnecessary crushing of the stems. The juice shall be poured through a sieve or metal screen strainer that will permit the juice to escape rapidly and at the same time not permit, under pressure, any pulp or solids to go through. In no case shall the screen or sieve be less than 8 mesh per lineal inch.

(b) When making a soluble solids test, a temperature compensated hand refractometer shall be used, the juice shall be thoroughly mixed and a small sample of the juice shall be placed upon the prism and read immediately to avoid evaporation. When the hand refractometer is used as a dipping instrument, the juice shall be thoroughly mixed and the refractometer shall be immersed to a depth that will ensure complete coverage of the prism for a period of 2 to 3 minutes for temperature equilibrium prior to reading.

(c) Prior to each grape season, hand refractometers shall be checked for optical accuracy by using a standard solution. If the instrument is not accurate, it shall not be used in any official testing procedure.

(d) When a test has been completed, the juice shall be drained or dried from all equipment before the juice from a subsequent test is used. The refractometer shall be washed and dried after each use.