When consumers outline the attributes that they would like their hair to have, softness is frequently mentioned. Measuring and quantifying hair softness can be achieved, rather counterintuitively, by measuring hair stiffness.

The 3-point cantilever bending technique is a test used to measure the flexibility of a hair tress. It involves applying a force at a specific point between two supports and measuring the amount of deflection at the middle point. The amount of deflection measured can be used, in this test, as a measure of softness.

The 3-point bend test, when performed on dry hair tresses, responds to changes in fiber bending properties and to changes in inter-fiber friction.  Experiments performed at TRI have shown that hair bleach damage, known to increase hair elastic modulus and surface roughness, increases the dry hair stiffness measured using the 3-point bend test.  In addition, it has been shown that hair conditioning products can reduce hair stiffness, making hair softer.