How do you measure softness?

Answer 1

One way to measure softness is to use a machine that records how much force is required to deform a sample of the material by a certain amount. The less force, the softer the material is.

Another way to measure softness is to have people feel a sample of the material and compare it to samples of other materials that already have softness ratings assigned to them.

The mechanical testing works very well for materials that are very uniform and are deformed in simple ways. The human sensory method works best for less uniform materials that are handled in more complicated ways (like bathroom tissue, for instance).