Suheg rubber industries

Durometer Technical Information

Measuring Suggestions

The basic principle used to measure hardness is invariably based on measurement of the resistance force  of the penetration of a pin into the test material put under a known spring load.  The amount of penetration of the pin (maximum 2.5 mm) is then converted to hardness reading  on a scale with 100 units

1. Whenever it is possible, a Durometer measurement  should be taken at least 12 mm (approximately 0.500") in from edge of a  sample, as the hardness characteristic of any sample changes at the edges.

2. Whenever it is possible, the sample thickness should exceed 6 mm  (approx. 0.250"). In case, the sample is thinner than this, the sample can be  backed with a sample of the same material to increase the thickness

3. Test  blocks should not be used for calibration verification. All samples are usually subject to characteristic  changes over a period of time along with temperature as well as lighting conditions, the rated Shore  value when supplied as new can and will vary with age. A proper calibration verification requires  independent confirmation of the internal spring forces along with the pin displacement verification  vs. the value identified on the scale.

Specimens need to be 0.250" thick, with a 1" surrounding area for accurate measurements to qualify for ASTM Durometer testing


Reference Guide & Scale Comparison