The majority of people envision a conventional orange fire when imagining flames. There are, however, numerous occasions in which fire does not burn orange. In fact, flames can include the entire range of colours. So, what produces the different hues of flames? What substances can change the colour of fire? And what is the role of temperature? We will shed light on all of the aforementioned and more.
What causes the different colours of flames?
To comprehend the causes of different-colored flames, it is necessary to comprehend the science underlying visible light and fire. First, fire is a chemical reaction that occurs when chemical and gas molecules mix with oxygen during combustion. Furthermore, not all fire resides within the visible light spectrum.
The visible light scale includes all electromagnetic radiation that is visible to the naked eye. As a result of light travelling through a prism, we perceive colours as we know them. We are able to distinguish distinct colours because their wavelengths differ. For instance, the wavelength of red is the longest, while that of violet is the shortest.
When flames display distinct hues, they are reacting to both heat and chemicals. The typical colour spectrum of fire ranges from moderately chilly to extremely hot, which is represented by the colour spectrum acronym ROYGBIV.
Red
Orange
Yellow
Green
Blue
Indigo
Violet
Which Color Best Depicts the Most Fiery Fire?
Despite its chilly appearance, violet is the hottest colour of flame. Violet flames’ extreme temperatures of approximately 1,650 degrees Celsius can easily cut through practically any metal, glass, or rock. As a result, violet and blue flames are frequently visible at the end of welding torches. Although welders use safety eyewear to prevent their eyes from being burned by the light,
It is also crucial to remember that the carbon and hydrogen present in burning wood form violet and blue flames. This is why you may observe blue or violet flickers while gathered around a campfire.
Red flames, which are the coolest, are not as intense as violet flames, which can char the hardest substances. Although red is a characteristically blazing hue, it is not the hottest flame, with temperatures between 600 and 800 degrees Celsius. This may seem like a high temperature, but when compared to the 1,650-degree blue flames, the red flames are very tame. Nonetheless, flames of this temperature are capable of melting aluminium, pure silver, tin, lead, bronze, and brass. Some red flames are so chilly that they are difficult to see with the naked eye, while flames that reach 800 degrees Fahrenheit burn a rosy red colour.
Clearly, there is a correlation between the intensity of a flame and the colour it burns. Compared to a blazing fire or a newly-ignited match, flames that are cooler or beginning to go out have a distinct colour. The colour of the flames indicates the quantity of heat and energy emitted during combustion. The colour spectrum’s hottest flame is violet, while the visible spectrum’s brightest flame is white.
Here is a more detailed analysis of the temperatures of various flame colours and the materials they may burn:
Red flames reach temperatures between 600 and 800 degrees Celsius. The brightest red flames can melt magnesium (657° C), glass (700° C), and borax (740° C), but the coolest red flames can melt lithium (179° C), selenium (220° C), tin (232° C), amber (300° C), and zinc (419° C).
The approximate temperature of orange flames is 1100 degrees Celsius. These flames can melt bronze (910 degrees Celsius), gold (1063 degrees Celsius), and copper (1083 degrees Celsius).
Yellow flames are around 1200 degrees Celsius in temperature. These flames will melt arsenic (815 degrees Celsius), calcium (850 degrees Celsius), brass (900 degrees Celsius), silver (960 degrees Celsius), and radium (960 degrees Celsius).
Intriguingly, green flames have no relation to temperature, but rather to their fuel chemistry, which will be discussed further below.
Blue flames reach temperatures between 1400 and 1650 degrees Celsius. This allows the coolest blue flames to melt asbestos (1300° C), steel (1460° C), and cobalt (1490° C), and the hottest blue flames to melt palladium (1552° C), brown iron ore (1570° C), molten clay (160°0 C), and agate (1600° C).
Indigo flames burn at just around 1650 degrees. These flames may liquefy aluminium bronze (1040 degrees Celsius), quartz (1470 degrees Celsius), iron oxide (1570 degrees Celsius), and sand (1550 degrees Celsius).
White flames reach temperatures between 1300 and 1500 degrees Celsius. These flames are capable of consuming numerous difficult solids, such as uranium (1133° C), nickel (1,452° C), and cobalt (1,490° C).
Violet flames burn beyond 1650 degrees. This renders these flames potent enough to melt materials that are notoriously difficult to melt, such as cast iron/forged iron (1200° C), steel (1460° C), porcelain (1650° C), and titanium (1670° C).
What substances alter the colour of flames?
Flame colour is not solely determined by temperature. Different hues of flames can also result from the presence of various compounds in the burning item. In addition to flame temperature, the type of fuel and its impurities influence the colour of the flame.
Certain compounds in wood, candles, and other fuel sources can produce flames of varied colours when ignited. In other words, both the fire’s temperature and the elements particles illuminating the flame determine its hue. These chemicals and materials are responsible for the distinct hues of fire:
Strontium chloride or strontium nitrate causes this colour. Observed in smouldering flames.
Orange: The result of the combustion of carbon or calcium chloride. Most campfires, charcoal barbecues, and fireplaces include ash.
Causing the colour yellow are sodium chloride, sodium carbonate, or borax.
Green: Attributable to copper or barium. No correlation with temperature.
Copper chloride or the full combustion of carbon in a fuel source produce the colour blue.
Indigo: The result of indium.
White: The result of magnesium sulphate.
Violet: The result of potassium nitrate and potassium sulphate together.
Why are orange flames so prevalent?
Why are orange flames the most prevalent (apparently) colour of fire? Orange flames reach temperatures of roughly 1100 degrees Celsius, placing them in the middle of the temperature spectrum for flames. The majority of organic materials that people burn, including paper, wood, and charcoal, contain carbon. Therefore, when these objects are burned, carbon particles are released into the flame, resulting in orange, “clear” orange, and yellow flames.
When all carbon particles have been eaten from a fuel source and there are no traces left to be consumed, the flame may flash blue or violet. For instance, stovetops and gas grills produce blue flames since their fuel sources are not carbon-based.
