Abstract: An instant reusable gel compress for applying cold or heat to a human or animal body part. The compress contains crystals of ammonium nitrate or calcium chloride, a water soluble acrylic polymer and an enclosed bag of water within a sealed, durable, flexible, plastic, bag-like container. When the interior water bag is broken, an immediate thermal reaction and simultaneous gel formation results. The resulting gel compress is then applied to the body part for cold or heat treatment. When the cold or heat is dissipated the gel compress itself may be chilled or heated again by an external source and then reused.

Abstract: A method of applying heat or cold to human or animal parts and a reusable compress utilized therein. The method involves saturating crystals of a water soluble acrylic polymer and a thickening agent through the porous fabric of a compress bag containing the acrylic polymer and the thickener. The compress is heated in a warm water or a microwave oven or cooled in a cool environment. The compress is applied to a human or animal part to warm or cool the body part. When the compress is no longer needed the gel is de-hydrated and the compress is easily stored for safe reuse.

Abstract: A heat pack comprised of a supercooled aqueous solution of sodium acetate and hydroxyethyl cellulose together with a plastic or glass disk or ampule containing sodium acetate crystals in a sealed, flexible container. Activation or crystallization of the sodium acetate portion of the solution is produced by breaking the disk or ampule and exposing the solution to the sodium acetate crystals.