Resisting Energy Transfer The Thermos bottle also called a Dewar flask is designed to minimize Vacuum energy transfer by conduction convection and radiation the standard flask is a double-walled Pyrex glass with silvered walls and Silvered the space between the walls is surfaces evacuated Hot or cold liquid Physics 121: Lecture 25, Pg 10Physics 121: Lecture 25, Pg 10 Resisting Energy Transfer The Thermos bottle, also called a Dewar flask is designed to minimize energy transfer by conduction, convection, and radiation. The standard flask is a double-walled Pyrex glass with silvered walls and the space between the walls is evacuated. Vacuum Silvered surfaces Hot or cold liquid