Patent ID: 7980242

Claim:
A method of making a hot/cold pack product comprising the steps of: providing an outer wall of water-proof sheet material allowing ready transmission of heat or cold therethrough; providing an inner wall of porous sheet material allowing the passage of water therethrough; sealing said outer wall of water-proof sheet material to said inner wall of porous sheet material with the outer wall of water-proof sheet material and said inner wall of porous sheet material being in face-to-face relationship to form a multi-laminate first sheet structure defining a plurality of spaced compartments therebetween, each of said compartments being completely sealed about the outer periphery thereof and the compartments being spaced from one another, and said outer wall of water-proof sheet material and the inner wall of porous sheet material sealed about the entire periphery of the first sheet structure and forming a peripheral seal between said outer wall of water-proof sheet material and said inner wall of porous sheet material extending entirely about all of said plurality of compartments; placing dehydrated gel material in said compartments; attaching insulating and water-proof second sheet structure to said first sheet structure at the peripheral seal between said outer wall of water-proof material and said inner wall of porous sheet material to define an interior between said first sheet structure and said insulating and water-proof second sheet structure, with said inner wall of porous sheet material and said compartments facing said insulating and water-proof second sheet structure; providing an opening between said first sheet structure and said insulating and water-proof second sheet structure communicating with said interior; introducing water through said opening into said interior to submerse said compartments in said water; and allowing water in said interior to enter the compartments through said porous sheet material and hydrate the dehydrated gel material therein; and selectively heating or cooling said hot/cold pack product after the step of hydrating the dehydrated gel material to heat or cool the hydrated gel material in said compartments.