Editing Combustion (section)

===Solid fuels===
[[File:disfig1.svg|thumb|upright=1.5|A general scheme of [[polymer]] combustion]]

The act of combustion consists of three relatively distinct but overlapping phases:
* '''Preheating phase''', when the unburned [[fuel]] is heated up to its flash point and then [[fire point]]. Flammable gases start being evolved in a process similar to [[dry distillation]].
* '''Distillation phase''' or '''gaseous phase''', when the mix of evolved flammable gases with oxygen is ignited. Energy is produced in the form of heat and light. [[Flame]]s are often visible. Heat transfer from the combustion to the solid maintains the evolution of flammable vapours.
* '''Charcoal phase''' or '''solid phase''', when the output of flammable gases from the material is too low for the persistent presence of flame and the [[charring|charred]] fuel does not burn rapidly and just glows and later only [[Smouldering|smoulders]].