The hardness of a foam is defined by the foam's ability to withstand piercing or indentation under force. Hardness is measured by a device called a durometer, which is the name of both the device used to measure hardness and the measurement itself. Durometers place the material's hardness on a scale from 1 to 100. The most common scales used are Shore or Asker. Foam hardness is given on the Shore OO or Asker F scale. While taking the measurement is easy, locating a durometer to use is difficult. Purchasing one is expensive, and they start around $400 dollars.
Things You'll Need
- A durometer
- Testing block
- Foam material
Make sure the durometer is set for the Shore OO or Asker F scale. The user manual provided with the durometer will say which foot -- the part that presses into the material -- and spring set is used for these scales.
Calibrate the durometer. Place the durometer on the testing block. Press down and hold for ten seconds. The measurement displayed on the durometer should match the given hardness of the testing block. If the reading is off, follow the instructions given for your durometer to calibrate it appropriately.
Place the material to be tested on a flat surface. Ensure that the material is thick enough to be tested without the durometer by measuring the hard surface underneath, generally 15 millimeters or greater. Samples may be stacked to achieve the required thickness.
Press the durometer down onto the foam sample. Hold for ten seconds and then record the number displayed by the durometer. Test several times and use an average for the measurement. Make sure to give measurements in the scale used -- for example, 88OO, which is 88 durometers on the Shore OO scale.
- Photo Credit pink foam image by laurent dambies from Fotolia.com
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