A chimney fire is the combustion of resiue deposits referred to as creosote, on the inner surfaces of chimney tiles, flue liners, stove pipes, etc. The process begins with the incomplete combustion (burning) of fuel in the attached appliance, usually a wood or coal stove. The unburned volatiles are heated to the vapor state but not consumed due to a lack of adequate heat and oxygen within the appliance. These volatile distillates escape into the chimney, where they contact cooler surfaces and condense into tar-like deposits. Successive layers accumulate until either the chimney plugs completely, or the chimney reaches a temperature and oxygen level at which the deposit will ignite. Due to the concentrated level of volatile material now present, these fires tend to burn very hot. The high temperatures stress the mechanical strength of the chimney causing distortion of metal structures, and failure of ceramic structures.