The Resilience/Elasticity is measured to ASTM 3574 standard this is measured by using a steel ball. The    height of rebouncing of the ball is measured. On a latex foam core the rebounce factor is higher than 60% to    70%. This is much higher compared to synthetic foams.

   It is important that the surfers of the mattress core is soft and when apply    pressure it increasingly shows the    resistance and come to the stop point. The sag factor is described through the ISO 2439 standard. The higher    this index, the better the foam supports the body contour. The natural latex foam performs obviously better    with a sag factor than synthetic products.

  The most accepted method is to test the mattress core    to the standards of EN 1957. A weight of 1400 Newton    is rolled 30000 times up and down on the mattress    core. Afterwards the height, the hardness and elasticity    is measured. This is repeated once again and the    results are compared with the original values. The    average incline of the hardness is determined at 210 N,    275 N and 340 N in the load deformation curve.
   The test of natural latex core by LGA Germany as per EN    1957 specifications the results were about 3 mm loss    in thickness and 3 % loss in hardness for a latex    mattress core.
   The other method is to test according to ISO 3385 (DIN    5374) standard, a foam sample of 40 x 40 cm forced    with a weight of 750 N for 80000 times at 70 strokes in    the minute. Afterwards, the loss of height and the    hardness is compared with the original value.

   The hysteresis can be determined by measuring the “banana foam” curve via loading and de-loading of a    mattress. The load deformation curve is measured by means of a circular plate of 355 mm diameter, that    gradually builds a force max. up to 1000 Newton.
   The hysteresis is calculated with the load and de-load curve by the load surface. The hysteresis indicates the    amount of energy that is absorbed by the latex core during loading / de-loading. The higher the absorption of    energy by a mattress core, the more strength / energy is required to change the position on the mattress. The    Mattress cores which is to soft, has a low hysteresis, results higher energy requirement for changing the    position on the mattress core. This results to a poor sleeping quality. The mattress core with the results of the    hysteresis between 20 - 30 % is a comfortable mattress.