11. Procedure
11.1 Unworked Penetration - Place the cup on the penetrometer table, making certain that it cannot teeter. Set the mechanism to hold the cone in the zero position, and adjust the apparatus carefully so that the tip of the cone just touches the surface at the center of the test specimen. Watching the shadow of the cone tip, from a low angle with backlighting, is an aid to accurate setting. For greases with penetrations over 400, the cup must be centered to within 0.3 mm (0.01 in.) of the tip of the cone. One way to center the cup accurately is to use a centering device (Fig. 1). Release the cone shaft rapidly, and allow it to drop for 5.0 more or less 0.1 s. The release mechanism should not drag on the shaft. Lock the shaft in position at the end of the 5-s period. Gently depress the indicator shaft until stopped by the cone shaft and read the penetration from the indicator.
11.1.1 If the sample has a penetration over 200, center the cone carefully in the cup; this sample can then be used for only one test. If the sample has a penetration of 200 or less, perform three tests in a single cup, spacing these tests on three radii 120° apart and midway between the center side of the cup so that the cone will neither strike the side of the container nor impinge on the disturbed area made in a previous test.
11.1.2 Additional Tests - Make a total of three tests on the specimen (either in three cups or in one, in accordance with 11.1.1), and report the average of the three tests, to the nearest 0.1 mm, as the unworked penetration of the specimen.
11.2 Worked Penetration - Determine the penetration of the specimen in accordance with 11.1.
11.2.1 Additional Tests - Immediately make two more tests in succession on the same specimen. Return to the cup the portion previously removed with the spatula, then repeat the operations in accordance with 8.4.2.2. Report the average of the three tests, to the nearest 0.1 mm, as the worked penetration of the specimen.
11.3 Prolonged Worked Penetration - Determine the penetration of the specimen in accordance with 11.1.
11.3.1 Additional Tests - Immediately make two more tests in succession on the same specimen. Return to the cup the portion previously removed with the spatula, then repeat the operations in accordance with 8.4.2.2. Report the average of the three tests, to the nearest 0.1 mm, as the prolonged worked penetration of the specimen.
11.4 Block Penetration - Place the test specimen on the penetrometer table with one of the prepared faces upward, and press it down by the corners to make it rest level and firmly on the table so that it cannot teeter during the test. Set the mechanism to hold the cone in the zero position, and adjust the apparatus carefully so that the tip of the cone just touches the surface at the center of the test sample. Determine the penetration in accordance with 11.1. Make a total of three tests on the exposed face of the specimen, locating the tests at least 6 mm (1/4 in.) from the edge and as far apart as possible without impinging on any touched portion, air hole, or other apparent flaw in the surface. If the result of one of these tests differs from the others by more than three units, make additional tests until three values agreeing within three units are obtained. Average these three values for the face being tested.
11.4.1 Additional Tests - Repeat the procedure described in 11.4 on each of the other prepared faces of the specimen. Report one third of the sum of the averages for the three faces, to the nearest 0.1 mm as the block penetration of the specimen.
