Rocks & mirror
Encyclopedia of Marine and Energy Technology



Smoke can be black, blue, white, yellow or brown in colour. Black smoke is mainly comprised of carbon particulates (soot). Blue smoke indicates the presence of the products of the incomplete combustion of the fuel or lubricating oil. White smoke is usually condensed water vapour. Yellow smoke is caused by NOx emissions. When the exhaust gas is cooled significantly prior to discharge to the atmosphere, the condensed NOcomponent can take brown colour.