Technically, Thermo-Trap is referred to as a heat sink. This means that it has an extremely high capacity for absorbing heat. Applied to the metal working surface between the area being heated and the material to be protected, Thermo-Trap soaks up heat and reduces heat transfer. This keeps heat from spreading beyond the work area. Heat-sensitive components, installed fittings, etc., on the other side of Thermo-Trap stay cool and are not damaged by transmitted heat.Apply to copper, steel or other pipe surfaces before welding, brazing or soldering to protect nearby sensitive controls or components. Protect adjacent surface areas from over-heating or damage prior to welding, brazing or soldering. Use to cool down heated surfaces. Prevent fires in adjacent areas when welding, brazing or soldering.