What is the difference between hardness and support? Hardness is the measurement of the surface touch or feel of the foam. Support, on the other hand, is the ability of the foam to push back against weight and prevents the foam from bottoming out under pressure. Hardness and support together affect foam comfort. The measurement that can determine foam support is defined as the Support Factor. It is the value obtained by dividing the hardness value at 65% compression by the hardness value at 25% compression. If the support factor is high, the foam is more comfortable and cozy. For load-bearing applications like cushions, foams with a support factor of 2 and above are suitable.

The hardness of the foam is one of its most important properties. If the foam is too hard or too soft, it can cause various problems in the customer's process. Consumers may encounter some problems regarding the hardness of the foam. This is of primary importance, especially in comfort applications. The fact that foam is hard does not mean it is durable and long-lasting. What matters is that the hardness value of the foam is evaluated together with other physical properties.

There are two methods to determine the hardness of the foam; these are ILD (Indentation Load Deflection) and CLD (Compression Load Deflection).

1. CLD (Compression Load Deflection): In measurements made using this method, the compressed sample must be larger than the disk where the compression is made. In this method, the sample is compressed 3 times up to 70% of its original thickness to perform pre-softening. Then, it is compressed to 40% of its original thickness and the hardness value is measured. For the accuracy of measurements, 4 samples are taken. The hardness obtained in measurements is expressed as kPa, which is the force on the surface. CLD measurements are performed in accordance with the ISO 3386-1 standard.

2. ILD (Indentation Load Deflection): In measurements made using this method, the compressed sample must be smaller than the disk where the compression is made. The sample should be 40cm * 40cm * 5cm in dimensions. First, the sample is compressed 3 times to 70% of its original thickness and preflexing is performed. Then, the hardness value at 25% of the original thickness is measured. Subsequently, the hardness value at 40% of the original thickness is measured, and finally, the hardness value at 65% is measured. 30 seconds should be waited before all hardness measurements. Generally, the hardness value at 40% compression is taken as the basis. Hardness measured with the ILD method is defined and unitized as force (Newton). In the ILD method, measurements are carried out in accordance with the ISO 2439 standard.