Asphalt cement, like most other materials, volatilizes (gives off vapor) when heated. At extremely high temperatures (well above those experienced in the manufacture and construction of HMA) asphalt cement can release enough vapor to increase the volatile concentration immediately above the asphalt cement to a point where it will ignite (flash) when exposed to a spark or open flame. This is called the flash point. For safety reasons, the flash point of asphalt cement is tested and controlled. The fire point, which occurs after the flash point, is the temperature at which the material (not just the vapors) will sustain combustion.