Example of wood which has been subject to high heat but where combustion was incomplete. During the combustion process, the visible flames within the fire come from the volatile compounds that are released from the wood, but the char itself burns without any flames and appears as glowing red embers. The composition of char is primarily carbon as the combustion of wood removes the oxygen and hydrogen constituents. The rate at which wood chars is a valuable means of establishing its fire rating in fire protection engineering.