question: Why do things turn black when burnt?
comment: Most things - 90% of all known chemicals - contain carbon, and carbon is* black. If the thing is completely oxidized all the carbon ends up as colourless CO2, but completely oxidizing a solid object using only atmospheric air and the heat it can produce on its own is quite hard, so some unburnt carbon is often left behind. *) depending on how it's arranged. In a cubic crystal lattice carbon is transparent, while flat sheets of carbon appear greyish. A bunch of carbon atoms jumbled together as happens when they're deposited during fire tends to look black though.
passages: Section::::Electroconductive carbon black production.
  
  Carbon black begins as a byproduct of what is referred to as partial oxidation, a process during which crude oil residues, such as vacuum residues from crude oil distillation or residues from the thermic cracking process, split due to the effects of the mixture of oxygen and water steam under high temperatures around 1,300 °C. 
   BULLET::::- Soot – auxiliary fuel (coal, hydrocarbons, crude oil) combustion product, which is considered to be a hazardous substance with carcinogenic properties.
   Section::::Pigment.
  
  Carbon black (Color Index International, PBK-7) is the name of a common black pigment, traditionally produced from charring organic materials such as wood or bone. It appears black because it reflects very little light in the visible part of the spectrum, with an albedo near zero. The actual albedo varies depending on the source material and method of production. It is known by a variety of names, each of which reflects a traditional method for producing carbon black:
  
  BULLET::::- Ivory black was traditionally produced by charring ivory or bones (see bone char).
   Black carbon particles (a component of soot) originating from combustion processes have been known for some time to absorb sunlight and warm the atmosphere, and pollution controls have been put into place to reduce their emissions and their effects.
   Partial oxidation of various raw materials always creates a gaseous mixture containing CO, CO2, H2O, H2, CH4 and H2S and COS formed from sulfurous compounds. Carbon black is formed as an undesired byproduct. The amount of carbon black grows as the injection's molecular weight increases. Methane gasification produces approx. 0.02% mass, crude oil residue gasification approx. 1-3% mass.
   Section::::Bleaching chemical pulps.:Ozone.
   In terms of surface interactions, chromium oxide is polar. The oxygen atoms on the surface have a permanent dipole moment, and are therefore hydrophilic. This means that water will wet it, but oils or other lipids will not.
  
  Section::::Materials in cooking.:Cast iron.
   While the function of black carbon created by biomass burning in relation to the warming of air has as of now been known, the lesser-known part of brown carbon has recently been discovered.
  
  Section::::Overview.:Discovery.:Brown carbon aerosols.
  
  The way light reflects off brown carbon causes the material to appear brown or yellow. In respect to soot carbon (as an aerosol called black carbon) these light reflecting particles are collectively called brown carbon, highlighting their optical properties.
   The coatings and inks industries prefer grades of carbon black that are acid-oxidized. Acid is sprayed in high-temperature dryers during the manufacturing process to change the inherent surface chemistry of the black. The amount of chemically-bonded oxygen on the surface area of the black is increased to enhance performance characteristics.
  
  Section::::Safety.
  
  Section::::Safety.:Carcinogenicity.
   The equation below displays some examples of roasting oxidation reactions used in refining zinc from sphalerite and other ores.
   Prior to cooking, the iron atom is in a +2 oxidation state, and bound to a dioxygen molecule (O), with a red color. As cooking proceeds, it loses an electron, moving to a +3 oxidation state, and coordinating with a water molecule (HO), turning brown in the process.
  
  Searing raises the meat’s surface temperature to , yielding browning via different reactions: caramelization of sugars, and the Maillard reaction of amino acids. Raised to a high enough temperature, meat blackens from burning.
  
  Section::::Drying.
   Coal and soot or carbon black are informally called amorphous carbon. However, they are products of pyrolysis (the process of decomposing a substance by the action of heat), which does not produce true amorphous carbon under normal conditions.
  
  Section::::Nanocarbons.
  
  Section::::Nanocarbons.:Buckminsterfullerenes.
   Section::::Physical and chemical characteristics of electroconductive carbon black.:Surface characteristics.
  
  Yet another noteworthy characteristic is carbon black's chemical surface composition. Chemisorbed complexes containing oxygen, such as carboxylic, quinonic or phenolic groups appear on carbon black surfaces. These groups, which contain oxygen, can significantly affect chemical reactivity, wettability, carbon black catalytic characteristics, electric conductivity, etc. 
  
  "Picture: Diagram of carbon black structure and texture creation"
  
  Section::::Applications.
  
  "Composite applications" 
  
  BULLET::::- "polymers (compounds, concentrates)"
  
  BULLET::::- "resins"
  
  BULLET::::- "rubbers"
  
  BULLET::::- "varnishes, paints, glues"
  
  Section::::Electroconductive carbon black producers.
   BULLET::::- At 200-300 °C, if oxygen has not been excluded, the carbonaceous residue may start to burn, in a highly exothermic reaction, often with no or little visible flame. Once carbon combustion starts, the temperature rises spontaneously, turning the residue into a glowing ember and releasing carbon dioxide and/or monoxide. At this stage, some of the nitrogen still remaining in the residue may be oxidized into nitrogen oxides like and . Sulfur and other elements like chlorine and arsenic may be oxidized and volatilized at this stage.
   Condensed aromatic ring structures indicate black carbon degradation in soil. Saprophytic fungi are being researched for their potential role in the degradation of black carbon.
  
  Section::::Policy options.
  
  Many countries have existing national laws to regulate black carbon emissions, including laws that address particulate emissions. Some examples include:
  
  BULLET::::- banning or regulating slash-and-burn clearing of forests and savannas;
  
  BULLET::::- requiring shore-based power/electrification of ships at port, regulating idling at terminals, and mandating fuel standards for ships seeking to dock at port;
   Like hot black oxide, mid-temperature black oxide converts the surface of the metal to magnetite (FeO). However, mid-temperature black oxide blackens at a temperature of , significantly less than hot black oxide. This is advantageous because it is below the solution's boiling point, meaning there are no caustic fumes produced.
  
  Since mid-temperature black oxide is most comparable to hot black oxide, it also can meet the military specification MIL-DTL-13924, as well as AMS 2485.
  
  Section::::Ferrous materials.:Cold black oxide.
   Section::::History.
  
  Section::::History.:Early years and formation (2001–2005).
   Absorption of light is contrasted by transmission, reflection and diffusion, where the light is only redirected, causing objects to appear transparent, reflective or white respectively. A material is said to be black if most incoming light is absorbed equally in the material. Light (electromagnetic radiation in the visible spectrum) interacts with the atoms and molecules, which causes the energy of the light to be converted into other forms of energy, usually heat. This means that black surfaces can act as thermal collectors, absorbing light and generating heat (see Solar thermal collector). 
  
  Section::::Science.:Chemistry.
  
  Section::::Science.:Chemistry.:Pigments.
   It was seen that particles from combustion or from residential coal usage can contain substantial amounts of brown carbon. This particulate matter appears light brown, and not black as would be expected for pure soot particles.
  
  Section::::Effects.
  
  Section::::Effects.:Influence on Earth's atmosphere.
   Sputtering observed to occur below the threshold energy of physical sputtering is also often called chemical sputtering. The mechanisms behind such sputtering are not always well understood, and may be hard to distinguish from chemical etching. At elevated temperatures, chemical sputtering of carbon can be understood to be due to the incoming ions weakening bonds in the sample, which then desorb by thermal activation. The hydrogen-induced sputtering of carbon-based materials observed at low temperatures has been explained by H ions entering between C-C bonds and thus breaking them, a mechanism dubbed "swift chemical sputtering".
  
  Section::::Applications and phenomena.
   Section::::Physical and chemical characteristics of electroconductive carbon black.:Surface.
   Soot is composed of a complex mixture of organic compounds which are weakly absorbing in the visible spectral region and a highly absorbing black component which is variously called “elemental”, “graphitic” or “black carbon”. The term elemental carbon has been used in conjunction with thermal and wet chemical determinations and the term graphitic carbon suggests the presence of graphite-like micro-crystalline structures in soot as evidenced by Raman Spectroscopy. The term black carbon is used to imply that this soot component is primarily responsible for the absorption of visible light. The term black carbon is sometimes used as a synonym for both the elemental and graphitic component of soot. It can be measured using different types of devices based on absorption or dispersion of a light beam or derived from noise measurements.
   Charcoal may be used as a source of carbon in chemical reactions. One example of this is the production of carbon disulphide through the reaction of sulfur vapors with hot charcoal. In that case the wood should be charred at high temperature to reduce the residual amounts of hydrogen and oxygen that lead to side reactions.
  
  Section::::Uses.:Purification and filtration.
   Section::::Physical and chemical characteristics of electroconductive carbon black.:Texture.
   Blackening (cooking)
  
  Blackening is a cooking technique used in the preparation of fish and other foods. Often associated with Cajun cuisine, this technique was popularized by chef Paul Prudhomme. The food is dipped in melted butter and then sprinkled with a mixture of herbs and spices, usually some combination of thyme, oregano, chili pepper, peppercorns, salt, garlic powder and onion powder. It is then cooked in a very hot cast-iron skillet. The characteristic brown-black color of the crust results from a combination of browned milk solids from the butter and charred spices.
  