Electronic Notes in Theoretical Computer Science

A cushion includes a core, a shell surrounding the core, and a flexible membrane interposed between the core and the shell. Both the core and shell are formed from foam material, with the foam material of the core being substantially stiffer upon initial loading than the foam material of the shell. The membrane is also formed from foam material, but is quite a bit denser than the foam material of either the core or shell. The overall effect of the membrane and the different load bearing characteristics for the two foam materials is a cushion which is quite soft to touch, but nevertheless capable of supporting heavy loading without excessive deflection. The cushion is produced by placing the core, which is cut from slab foam, into a mold cavity and then molding the shell about it. The amount of liquid reaction material introduced into the cavity, that is the amount of precursors for the foam of the shell, is in excess of the amount necessary to fill the cavity, and the overfill densifies at the surface of the core, forming the membrane.