Dead Foam :

Foam that has a low resiliency and only slowly regains its original shape after deformation.

Deflect:

To compress, usually by a specified amount or percentage.

Densified :

A material that has been made more dense by permanently compressing a unit mass into a smaller volume.

Density :

A measurement of the mass per unit volume. It is measured and expressed in pounds per cubic foot (pcf) or kilograms per cubic meter (kg/m3) (Test Method ASTM D3574).

Die Cutting :

The ”stamping out” of foam into parts, useful for long runs of cut parts requiring consistency in size.

Discoloration :

The gradual yellowing of foam due to a photochemical reaction. It is faster in sunlight than in artificial light, although it occurs in both. Fresh foam may discolor in the center of the block as a result of thermal or chemical events. (Does not affect physical properties.)

Dish :

Description of what occurs when a weight is placed on the center of a cushion or mattress and the corners rise up in response.

Durability :

As applied to flexible foams, the term refers to how well a foam retains its load bearing capacity and shape with use. Most measures of durability are done with laboratory-scale tests.

Dynamic Fatigue :

A durability test performed in the laboratory using roller-shear or pounding type mechanisms. A roller, longer than the foam width, is rolled back and forth across the foam. The roller is mounted in an offset position to impart a shearing action. (ASTM D3574).