Abstract: Thermal insulator is formed by adding a sufficient quantity of water to a superabsorbent polymer in a flexible container to form a gel. The polymer is lightly crosslinked potassium polyacrylate. The gel-holding flexible container may then be wrapped around or otherwise positioned to envelop a vial containing a temperature-sensitive specimen. The gel-holding flexible container is an effective thermal insulator which protects the specimen from potentially harmful extremes of temperatures, and also cushions the specimen-containing vial against mechanical shock.