Softening

Softening is the process by which a material or substance becomes less stiff or resistant to deformation. It can result from heating, moisture absorption, chemical changes, or time-dependent effects, and is described in many fields as a reduction in stiffness, hardness, or modulus. Softening is the opposite of hardening.

In materials science, softening is observed as a drop in modulus with temperature, often described by the softening point or the glass transition temperature in polymers. Annealing, normalizing, or tempering can soften metals by reducing dislocation density. In polymers, plasticization or aging reduces stiffness and yield strength.

In geology, rocks and soils can soften under elevated temperatures, high pressures, or chemical alteration, becoming more ductile and deforming by creep. Weathering and hydrothermal alteration can reduce stiffness and strength, affecting crustal stability, faulting, and excavation behavior.

In food science, softening occurs during cooking or soaking when water uptake, starch gelatinization, and protein denaturation change texture, making foods easier to chew and digest.

The term is also used metaphorically to describe a decline in intensity or firmness, such as softening demand in a market or a softer stance in negotiations.