User:KDS4444/List of shore durometers
The durometer score of a substance is a measure of its ability to resist permanent indentation as measured by an instrument also referred to as a durometer. Such measurements are usually applied to various polymers including elastomers, thermoplastics, and thermosets.
The durometer scale actually consists of 12 overlapping scales, each intended to measure a hardness in a different range of applications. According to the American Society for the Testing of Materials standard number D2240, "Hardness", these scales have the following names ranging from softest to hardest: A, B, C, D, DO, E, M, O, OO, OOO, OOO-S, and R. Because the ranges of these tables overlap, a material can have a score on more than one table. The most commonly encountered scores are shore A (for rubbers) and shore D (for heat formed plastics and thermosetting resins). Only these two shore scales are included in the table below.
Scores are achieved by with an indenter loaded by a spring. The indenter pushes down on the material with a given force that depends on its scale of measurement. A shore A indenter, for example, pushes downward with a force equal to 1.812 pounds (822 g), while a shore D indenter uses 10 pounds (4,500 g). Results are indicated in degrees (°) of difference between a small, initial force and the final force. The maximum penetration of a scale ends at 0.097-0.100 inches (2.5 mm) of penetration, corresponding to a theoretical score of zero° on that scale, while a score of 100° means no penetration was observed°. Scores are inherently somewhat ambiguous, and a variation of 5° between different measurements of the same material is common.
Note that shore hardness is only one measure of a material's characteristics. Stiffness and compressive modulus are other equally important qualities of an elastomer.
The following table represents typical shore hardnesses of various materials measured at given scales.
| Material | Shore A | Shore D |
|---|---|---|
| Rubber band | 35° | 7° |
| Art gum eraser | 30° | 6° |
| Nitrile | 50-90° | |
| Viton, sheet | 65-75° | |
| Shoe heel | 70° | 22° |
| Golf ball | 60° | |
| Polysulfide rubber | 12-20° | |
| Tin-cure silicone rubber | 10-60° | |
| Platinum-cure silicone rubber | 15-50° | |
| High-density urethane tooling resin | 82° | |
| Vibram rubber, soft | 65-70° | |
| Vibram rubber, firm | 75-80° | |
| Neolite styrene-butadeine rubber | 93-96° |