While most heat treaters temper or draw in air or "products of combustion", there are a group of heat treaters that process work in vacuum temper furnaces. These furnaces remove air and water vapor prior to heating the work using a vacuum pump. Much of the work is done at 800 to 1200°F and once the tempering process is complete, the work must be cooled to prevent oxidation that would occur if it was pulled from the furnace at these high temperatures. This paper will review both an internal style cooling system as well as a blower assisted externally cooled system. A review of different materials that can benefit from vacuum tempering will also be discussed.