Gardner/Sward Hardness Rocker

1. Energize the digital counter. This is done by placing the black switch on the back of the instrument in the "up” position.
2. Normally, when energized, one or more of the “0” digits will change to another number.
3. Place the rocker on a test surface and rotate it to the left to an angle greater than where count starts. This is over 22 degrees. All numbers on the display will return to zero.
4. Release the rocker. As soon as the swing amplitude reaches the high set limit, the counter automatically registers each swing cycle and continues to do so until the swing amplitude drops below the low set limit. This count of swing cycles between the high and low set limits remains on the display until further action is taken by the operator.
5. To repeat a reading, simply rotate the rocker, as in step three above, and repeat step four.
6. At the conclusion of a series of tests, return the switch on the back of the instrument to the lower position and place the instrument in secure storage.
7. Replace the battery if the count is erratic or becomes dim. Under normal conditions, a fresh battery should provide about 400 hours of count operation.

Procedure for Calibration

The Rocker is calibrated by the manufacturer to record 50 ±1 swing cycles in 60 ±5 seconds on the plate glass surface of the leveling plate used by the manufacturer and when operated in accordance with the detailed instructions furnished with the instrument. The hardness rocker is very sensitive and may not give exactly the same readings on other plate glass surfaces even when cleaned in the same manner or when readings are taken in different directions on the same glass surface.