ASTM D531-00 pdf free.Standard Test Method for Rubber Property—Pusey and Jones Indentation.
Make no less than 3 such determinations on thespecimen at least 13 mm (0.51 in) apart and from any edge.6.2.9 The median of the determinations，expressed as awhole number indicating hundredths of millimeters， shall bereported as the Pusey and Jones Indentation Value,refer to8.1.1.
When tests are performed on specimens other thanthose described in 5.1 and without the specimen holder and support the results shall be compared only to those obtained onsimilarly configured specimens under similar conditions.
A small vibrator which is activated prior tothe mass being applied to the indentor and operates continu-ously during a test to overcome any friction in the apparatus.An instrument that vibrates approximately 120 times per s,with an amplitude of vibration of the fixed platform of thetester varying from approximately 0.002 to 0.005 mm (0.0001to 0.0002 in.), has been found satisfactory.Such a vibrator may consist of a simplecored solenoidfastened to the top of a Cshaped piece of strap steel.The lowerpart of the solenoid core is a loose cylindrical piece of steelwith a shoulder at its lower end. When the current is off， theloose-cored section rests on a screw projecting from the bottomof the C-shaped support. When the current is on, the loose-cored section is attached to the solenoid but is restrained by aflat split ring of spring brass through which the cored sectionpasses， and which bears on the shoulder of the cored section.The cored section is caused to vibrate by the alternating forcesof attraction by the solenoid and repulsion by the flat ringacting as a spring. A small plate bearing a toggle switch forclosing the circuit to the solenoid is fastened to the top of theC-shaped piece of strap steel by means of the same bolt thatholds the solenoid. The bottom of the C-shaped piece isfastened by screws to a portion of a brass nut that serves toclamp the vibrator to one upright post of the tester.
The tests shall be conducted in the standard laboratoryatmosphere as defined in D 618,Terminology: “standard labo-ratory atmosphere”.ASTM D531 pdf download.