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A candle is an ignitable wick embedded in wax, or another flammable solid substance such as tallow, that provides
light Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...
, and in some cases, a fragrance. A candle can also provide
heat In thermodynamics, heat is energy in transfer between a thermodynamic system and its surroundings by such mechanisms as thermal conduction, electromagnetic radiation, and friction, which are microscopic in nature, involving sub-atomic, ato ...
or a method of keeping
time Time is the continuous progression of existence that occurs in an apparently irreversible process, irreversible succession from the past, through the present, and into the future. It is a component quantity of various measurements used to sequ ...
. Candles have been used for over two millennia around the world, and were a significant form of indoor lighting until the invention of other types of light sources. Although
electric light Electric light is an artificial light source powered by electricity. Electric Light may also refer to: * Light fixture, a decorative enclosure for an electric light source * Electric Light (album), ''Electric Light'' (album), a 2018 album by James ...
has largely made candle use nonessential for illumination, candles are still commonly used for functional, symbolic and aesthetic purposes and in specific cultural and religious settings. Early candles may be made of beeswax, but these candles were expensive and their use was limited to the elite and the churches. Tallow was a cheaper but a less aesthetically pleasing alternative. A variety of different materials have been developed in the modern era for making candles, including
paraffin wax Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and melting poi ...
, which together with efficient production techniques, made candles affordable for the masses. Various devices can be used to hold candles, such as candlesticks, or candelabras,
chandelier A chandelier () is an ornamental lighting device, typically with spreading branched supports for multiple lights, designed to be hung from the ceiling. Chandeliers are often ornate, and they were originally designed to hold candles, but now inca ...
s,
lantern A lantern is a source of lighting, often portable. It typically features a protective enclosure for the light sourcehistorically usually a candle, a oil lamp, wick in oil, or a thermoluminescence, thermoluminescent Gas mantle, mesh, and often a ...
s and sconces. A person who makes candles is traditionally known as a chandler. The combustion of the candle proceeds in a self-sustaining manner. As the wick of a candle is lit, the heat melts and ignites a small amount of solid fuel (the wax), which vaporizes and combines with
oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
in the air to form a flame. The flame then melts the top of the mass of solid fuel, which moves upward through the wick via
capillary action Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of external forces like Gravitation, gravity. The effe ...
to be continually burnt, thereby maintaining a constant flame. The candle shortens as the solid fuel is consumed, so does the wick. Wicks of pre-19th century candles required regular trimming with scissors or " snuffers" to promote steady burning and prevent smoking. In modern candles, the wick is constructed so that it curves over as it burns, and the end of the wick gets trimmed by itself through incineration by
fire Fire is the rapid oxidation of a fuel in the exothermic chemical process of combustion, releasing heat, light, and various reaction Product (chemistry), products. Flames, the most visible portion of the fire, are produced in the combustion re ...
.European Candle Association FAQ
.


Etymology

The word candle comes from
Middle English Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman Conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old English pe ...
, from
Old English Old English ( or , or ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the Early Middle Ages. It developed from the languages brought to Great Britain by Anglo-S ...
and from Anglo-Norman , both from
Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
, from 'to shine'.


History

Prior to the invention of candles, ancient people used open fire, torches, splinters of resinous wood, and lamps to provide artificial illumination at night. Primitive
oil lamp An oil lamp is a lamp used to produce light continuously for a period of time using an oil-based fuel source. The use of oil lamps began thousands of years ago and continues to this day, although their use is less common in modern times. The ...
s in which a lit wick rested in a pool of oil or fat were used from the
Paleolithic The Paleolithic or Palaeolithic ( years ago) ( ), also called the Old Stone Age (), is a period in human prehistory that is distinguished by the original development of stone tools, and which represents almost the entire period of human prehist ...
period, and pottery and stone lamps from the
Neolithic The Neolithic or New Stone Age (from Ancient Greek, Greek 'new' and 'stone') is an archaeological period, the final division of the Stone Age in Mesopotamia, Asia, Europe and Africa (c. 10,000 BCE to c. 2,000 BCE). It saw the Neolithic Revo ...
period have been found. Because candle making requires a reliable supply of animal or vegetable fats, it is certain that candles could not have developed before the early
Bronze Age The Bronze Age () was a historical period characterised principally by the use of bronze tools and the development of complex urban societies, as well as the adoption of writing in some areas. The Bronze Age is the middle principal period of ...
; however, it is unclear when and where candles were first used. Objects that could be candlesticks have been found in Babylonian and middle Minoan cultures, as well in the
tomb of Tutankhamun The tomb of Tutankhamun (reigned ), a pharaoh of the Eighteenth Dynasty of Egypt, Eighteenth Dynasty of ancient Egypt, is located in the Valley of the Kings. The tomb, also known by its List of burials in the Valley of the Kings, tomb number KV ...
. The "candles" used in these early periods would not have resembled the current forms; more likely they were made of plant materials dipped in animal fat. Early evidence of candle use may be found in Italy, where a depiction of a candlestick exists in an Etruscan tomb at
Orvieto Orvieto () is a city and ''comune'' in the Province of Terni, southwestern Umbria, Italy, situated on the flat summit of a large butte of volcanic tuff. The city rises dramatically above the almost-vertical faces of tuff cliffs that are compl ...
, and the earliest excavated Etruscan candlestick dates from the 7th century BC. Candles may have evolved from taper with wick of oakum and other plant fibre soaked in fat, pitch or oil and burned in lamps or pots. Candles of antiquity were made from various forms of natural fat, tallow, and wax, and Romans made true dipped candles from tallow and beeswax. Beeswax candles were expensive and their use was limited to the wealthy, so oil lamps were the more commonly used lighting devices in Roman times.
Ancient Greece Ancient Greece () was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity (), that comprised a loose collection of culturally and linguistically r ...
used torches and oil lamps, and likely adopted candle use in a later period from Rome. Early record in China suggests that candles were used in the
Qin dynasty The Qin dynasty ( ) was the first Dynasties of China, imperial dynasty of China. It is named for its progenitor state of Qin, a fief of the confederal Zhou dynasty (256 BC). Beginning in 230 BC, the Qin under King Ying Zheng enga ...
before 200 BC. These early Chinese candles may have been made from whale fat. In Christianity, candles gained significance in their decorative, symbolic and ceremonial uses in churches. Wax candles, or ''candela cerea'' recorded at the end of the 3rd century, were documented as Easter candles in Spain and Italy in the fourth century, the Christian festival Candlemas was named after it, and Pope Sergius I instituted the procession of lighted candles.
Papal bull A papal bull is a type of public decree, letters patent, or charter issued by the pope of the Catholic Church. It is named after the leaden Seal (emblem), seal (''bulla (seal), bulla'') traditionally appended to authenticate it. History Papal ...
s decreed that tallow be excluded for use in altar candles, and a high beeswax content is necessary for candles of the high altar. In medieval Europe, candles were initially used primarily in Christian churches. Their use spread later to the households of the wealthy as a luxury item. In Northern Europe, especially England, rushlight made of greased rushes were commonly used, but tallow candles were used during the Middle Ages, with a mention of tallow candles in English appearing in 1154. Beeswax was widely used in church ceremonies. Compared to animal-based tallow, it burns cleanly without smoky flame, and does not release an unpleasant smell like tallow. Beeswax candles were expensive, and relatively few people could afford to burn them in their homes in medieval Europe. The candles were produced using a number of methods: dipping the wick in molten fat or wax, rolling the candle by hand around a wick, or pouring fat or wax onto a wick to build up the candle. In the 14th century Sieur de Brez introduced the technique of using a mould, but real improvement for the efficient production of candles with mould was only achieved in the 19th century. Wax and tallow candles were made in monasteries in the medieval period, and in rural households, tallow candles were made at home. By the 13th century, candle making had become a guild craft in England and France, with a French guild documented as early as 1061. The candle makers (chandlers) went from house to house making candles from the kitchen fats saved for that purpose, or made and sold their own candles from small candle shops. By the 16th century, beeswax candles were appearing as luxury household items among the wealthy. Candles were widely used in the 17th and 18th centuries, and a party in
Dresden Dresden (; ; Upper Saxon German, Upper Saxon: ''Dräsdn''; , ) is the capital city of the States of Germany, German state of Saxony and its second most populous city after Leipzig. It is the List of cities in Germany by population, 12th most p ...
was said to have been lit by 14,000 candles in 1779. In the Middle East, during the
Abbasid The Abbasid Caliphate or Abbasid Empire (; ) was the third caliphate to succeed the prophets and messengers in Islam, Islamic prophet Muhammad. It was founded by a dynasty descended from Muhammad's uncle, Abbas ibn Abd al-Muttalib (566–653 C ...
and
Fatimid The Fatimid Caliphate (; ), also known as the Fatimid Empire, was a caliphate extant from the tenth to the twelfth centuries CE under the rule of the Fatimid dynasty, Fatimids, an Isma'ili Shi'a dynasty. Spanning a large area of North Africa ...
Caliphates, beeswax was the dominant material used for candle making. Beeswax was often imported from long distances; for example, candle makers from Egypt used beeswax from
Tunis Tunis (, ') is the capital city, capital and largest city of Tunisia. The greater metropolitan area of Tunis, often referred to as "Grand Tunis", has about 2,700,000 inhabitants. , it is the third-largest city in the Maghreb region (after Casabl ...
. As in Europe, these candles were expensive and limited to the elite, and most commoners used oil lamps instead. According to legend, the practice of using lamps and candles in mosque started with Tamim al-Dari who lit a lamp he brought from Syria in the
Prophet's Mosque The Prophet's Mosque () is the List of the oldest mosques, second mosque built by the Prophets and messengers in Islam, Islamic prophet Muhammad in Islam, Muhammad in Medina, after the Quba Mosque, as well as the second List of large mosques, la ...
in Medina. The
Umayyad The Umayyad Caliphate or Umayyad Empire (, ; ) was the second caliphate established after the death of the Islamic prophet Muhammad and was ruled by the Umayyad dynasty. Uthman ibn Affan, the third of the Rashidun caliphs, was also a membe ...
caliph Al-Walid II was known to have used candles in the court in Damascus, while the Abbasid caliph al-Mutawakkil was said to have spent 1.2 million silver
dirham The dirham, dirhem or drahm is a unit of currency and of mass. It is the name of the currencies of Moroccan dirham, Morocco, the United Arab Emirates dirham, United Arab Emirates and Armenian dram, Armenia, and is the name of a currency subdivisi ...
s annually on candles for his royal palaces. In early modern Syria, candles were in high demand by all socioeconomic classes because they were customarily lit during marriage ceremonies. There were candle makers' guilds in the Safavid capital of
Isfahan Isfahan or Esfahan ( ) is a city in the Central District (Isfahan County), Central District of Isfahan County, Isfahan province, Iran. It is the capital of the province, the county, and the district. It is located south of Tehran. The city ...
during the 1500s and 1600s. However, candle makers had a relatively low social position in Safavid Iran, comparable to barbers, bathhouse workers, fortune tellers, bricklayers, and porters. In the 18th and 19th centuries, spermaceti, a waxy substance produced by the
sperm whale The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the Genus (biology), genus ''Physeter'' and one of three extant species in the s ...
, was used to produce a superior candle that burned longer, brighter and gave off no offensive smell. Later in the 18th century, colza oil and rapeseed oil came into use as much cheaper substitutes.


Modern era

A number of improvements were made to candle in the 19th century. In older candles, the wick of a burning candle was not in direct contact with air, so it charred instead of being burnt. The charred wick inhibited further burning and produced black smoke, so the wick needed to be constantly trimmed or "snuffed". In 1825, a French man M. Cambacérès introduced the plaited wick soaked with mineral salts, which when burnt, curled towards the outer edge of the flame and become incinerated by it, thereby trimming itself. These are referred to as "self-trimming" or "self-consuming" wicks. In 1823,
Michel Eugène Chevreul Michel Eugène Chevreul (; 31 August 1786 – 9 April 1889) was a French chemist whose work contributed to significant developments in science, medicine, and art. Chevreul's early work with animal fats revolutionized soap and candle manufacturing ...
and Joseph Louis Gay-Lussac separate out
stearin Stearin , or tristearin, or glyceryl tristearate is an odourless, white powder. It is a triglyceride derived from three units of stearic acid. Most triglycerides are derived from at least two and more commonly three different fatty acids. Like ...
in animal fats, and obtained a patent in 1825 to produce candles that are harder and can burn brighter. The manufacture of candles became an industrialized mass market in the mid 19th century. In 1834, Joseph Morgan, a pewterer from
Manchester Manchester () is a city and the metropolitan borough of Greater Manchester, England. It had an estimated population of in . Greater Manchester is the third-most populous metropolitan area in the United Kingdom, with a population of 2.92&nbs ...
, England, patented a machine that revolutionised candle making. It allowed for continuous production of molded candles by using a cylinder with a moveable piston to eject candles as they solidified. This more efficient mechanized production produced about 1,500 candles per hour. This allowed candles to be an affordable commodity for the masses. In the mid-1850s, James Young succeeded in distilling
paraffin wax Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and melting poi ...
from coal and oil shales at
Bathgate Bathgate ( or , ) is a town in West Lothian, Scotland, west of Livingston, Scotland, Livingston and adjacent to the M8 motorway (Scotland), M8 motorway. Nearby towns are Linlithgow, Livingston, and West Calder. A number of villages fall under ...
in West Lothian and developed a commercially viable method of production. Paraffin could be used to make inexpensive candles of high quality. It was a bluish-white wax, which burned cleanly and left no unpleasant odor, unlike tallow candles. By the end of the 19th century, candles were made from paraffin wax and
stearic acid Stearic acid ( , ) is a saturated fatty acid with an 18-carbon chain. The IUPAC name is octadecanoic acid. It is a soft waxy solid with the formula . The triglyceride derived from three molecules of stearic acid is called stearin. Stearic acid ...
. By the late 19th century, Price's Candles, based in London, was the largest candle manufacturer in the world. Founded by William Wilson in 1830, the company pioneered the implementation of the technique of steam distillation, and was thus able to manufacture candles from a wide range of raw materials, including skin fat, bone fat, fish oil and industrial greases. Despite advances in candle making, the candle industry declined rapidly upon the introduction of superior methods of lighting, including
kerosene Kerosene, or paraffin, is a combustibility, combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in Aviation fuel, aviation as well as households. Its name derives from the Greek (''kērós'') meaning " ...
and lamps and the 1879 invention of the incandescent light bulb. From this point on, candles came to be marketed as more of a decorative item.


Use

Before the invention of
electric light Electric light is an artificial light source powered by electricity. Electric Light may also refer to: * Light fixture, a decorative enclosure for an electric light source * Electric Light (album), ''Electric Light'' (album), a 2018 album by James ...
ing, candles and oil lamps were commonly used for illumination. In areas without electricity, they are still used routinely. Until the 20th century, candles were more common in northern Europe. In southern Europe and the Mediterranean, oil lamps predominated. In the developed world today, candles are used mainly for their aesthetic value and scent, particularly to set a soft, warm, or romantic ambiance, or for emergency lighting during electrical
power failure A power outage, also called a blackout, a power failure, a power blackout, a power loss, a power cut, or a power out is the complete loss of the electrical power network supply to an end user. There are many causes of power failures in an el ...
s. Candles, however, are still commonly used in religious and ceremonial contexts. Examples include votive candles, Paschal candles and yahrzeit candles. In the days leading to Christmas, some people burn a candle a set amount to represent each day, as marked on the candle. The type of candle used in this way is called the '' Advent candle'', although this term is also used to refer to a candle that are used in an
Advent wreath The Advent wreath, or Advent crown, is a Christian tradition that symbolizes the passage of the four weeks of Advent in the liturgical calendar of the Western Christianity, Western church. It is traditionally a Lutheran practice, although it ...
. Symbolic use of candles has extended from the religious to the secular, for example, a candlelight vigil may be held in remembrance for a person, for a cause or an event, or as a form of political action or protest. In a social setting, candles are commonly used on birthday cakes. In the 21st century, there has been a huge spike in sales of scented candles in recent years. The
COVID-19 pandemic The COVID-19 pandemic (also known as the coronavirus pandemic and COVID pandemic), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began with an disease outbreak, outbreak of COVID-19 in Wuhan, China, in December ...
and the ensuing lockdowns led to a dramatic increase in the sales of scented candles, diffusers and room sprays.


Other uses

With the fairly consistent and measurable burning of a candle, a common use of candles was to tell the
time Time is the continuous progression of existence that occurs in an apparently irreversible process, irreversible succession from the past, through the present, and into the future. It is a component quantity of various measurements used to sequ ...
. The candle designed for this purpose might have time measurements, usually in hours, marked along the wax. The
Song dynasty The Song dynasty ( ) was an Dynasties of China, imperial dynasty of China that ruled from 960 to 1279. The dynasty was founded by Emperor Taizu of Song, who usurped the throne of the Later Zhou dynasty and went on to conquer the rest of the Fiv ...
in China (960–1279) used candle clocks. By the 18th century, candle clocks were being made with weights set into the sides of the candle. As the candle melted, the weights fell off and made a noise as they fell into a bowl.


Components


Wax

For most of recorded history candles were made from tallow (rendered from beef or mutton-fat) or beeswax. From the mid-1800s, they were also made from spermaceti, a waxy substance derived from the
Sperm whale The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the Genus (biology), genus ''Physeter'' and one of three extant species in the s ...
, which in turn spurred demand for the substance. Candles were also made from
stearin Stearin , or tristearin, or glyceryl tristearate is an odourless, white powder. It is a triglyceride derived from three units of stearic acid. Most triglycerides are derived from at least two and more commonly three different fatty acids. Like ...
(initially manufactured from animal fats but now produced almost exclusively from palm waxes). Today, most candles are made from
paraffin wax Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and melting poi ...
, a byproduct of
petroleum Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring un ...
refining.Franz Willhöft and Fredrick Horn "Candles" in Ullmann's Encyclopedia of Industrial Chemistry, 2000, Wiley-VCH, Weinheim. Candles can also be made from microcrystalline wax, beeswax (a byproduct of honey collection), gel (a mixture of
polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...
and
mineral oil Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum, as distinct from usually edible vegetable oils. The name 'mineral oil' by itself is imprecise, ...
), or some plant waxes (generally palm,
carnauba Carnauba (; ), also called Brazil wax and palm wax, is a wax of the leaves of the carnauba palm '' Copernicia prunifera'' (synonym: ''Copernicia cerifera''), a plant native to and grown only in the northeastern Brazilian states of Ceará, Pia ...
, bayberry, or soybean wax). The size of the flame and corresponding rate of burning is controlled largely by the candle wick. The kind of wax also affects the burn rate, with beeswax and coconut wax burning longer than paraffin or soy wax. Production methods utilize extrusion moulding. More traditional production methods entail
melting Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which inc ...
the solid fuel by the controlled application of heat. The liquid is then poured into a mould, or a wick is repeatedly immersed in the liquid to create a dipped tapered candle. Often fragrance oils,
essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the ...
s or aniline-based dye is added.


Wick

A candle wick works by
capillary action Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of external forces like Gravitation, gravity. The effe ...
, drawing ("wicking") the melted wax or
fuel A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work (physics), work. The concept was originally applied solely to those materials capable of releasing chem ...
up to the flame. When the liquid fuel reaches the flame, it vaporizes and combusts. The candle wick influences how the candle burns. Important characteristics of the wick include diameter, stiffness, fire resistance, and tethering. A candle wick is a piece of string or cord that holds the flame of a candle. Commercial wicks are made from braided cotton. The wick's capillarity determines the rate at which the melted hydrocarbon is conveyed to the flame. If the capillarity is too great, the molten wax streams down the side of the candle. Wicks are often infused with a variety of
chemical A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combin ...
s to modify their burning characteristics. For example, it is usually desirable that the wick not glow after the flame is extinguished. Typical agents are
ammonium nitrate Ammonium nitrate is a chemical compound with the formula . It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, but does not form hydrates. It is predominantly us ...
and ammonium sulfate.


Characteristics


Light

Based on measurements of a taper-type, paraffin wax candle, a modern candle typically burns at a steady rate of about 0.1 g/min, releasing heat at roughly 80 W. The light produced is about 13  lumens, for a luminous efficacy of about 0.16 lumens per watt (luminous efficacy of a source) – almost a hundred times lower than an incandescent light bulb. If a 1 
candela The candela (symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous to radi ...
source emitted uniformly in all directions, the total radiant flux would be only about 18.40 mW. The
luminous intensity In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the huma ...
of a typical candle is approximately one
candela The candela (symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous to radi ...
. The SI unit, candela, was in fact based on an older unit called the '' candlepower'', which represented the luminous intensity emitted by a candle made to particular specifications (a "standard candle"). The modern unit is defined in a more precise and repeatable way, but was chosen such that a candle's luminous intensity is still about one candela.


Temperature

The hottest part of a candle flame is just above the very dull blue part to one side of the flame, at the base. At this point, the flame is about . However, this part of the flame is very small and releases little heat energy. The blue color is due to chemiluminescence, while the visible yellow color is due to radiative emission from hot soot particles. The soot is formed through a series of complex chemical reactions, leading from the fuel molecule through molecular growth, until multi-carbon ring compounds are formed. The thermal structure of a flame is complex, hundreds of degrees over very short distances leading to extremely steep temperature gradients. On average, the flame temperature is about . The color temperature is approximately 1,000 K.


Combustion

For a candle to burn, a heat source (commonly a naked flame from a match or lighter) is used to light the candle's wick, which melts and vaporizes a small amount of fuel (the wax). Once vaporized, the fuel combines with
oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
in the atmosphere to ignite and form a constant flame. This flame provides sufficient heat to keep the candle burning via a self-sustaining chain of events: the heat of the flame melts the top of the mass of solid fuel; the liquefied fuel then moves upward through the wick via
capillary action Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of external forces like Gravitation, gravity. The effe ...
; the liquefied fuel finally vaporizes to burn within the candle's flame. As the fuel (wax) is melted and burned, the candle becomes shorter. The end of the plaited wick bends and get consumed in the flame. The incineration of the wick limits the length of the exposed portion of the wick, thus maintaining a constant burning temperature and rate of fuel consumption. Pre-19th century wicks required regular trimming with scissors (or a specialized wick trimmer), usually to about one-quarter inch (~0.7 cm), to promote steady burning and to prevent it from releasing black smoke. Special candle scissors called " snuffers" were produced for this purpose in the 20th century and were often combined with an extinguisher. In modern candles, the wick is made in such a way that it curves over as it burns, which ensures that the end of the wick gets incinerated by
fire Fire is the rapid oxidation of a fuel in the exothermic chemical process of combustion, releasing heat, light, and various reaction Product (chemistry), products. Flames, the most visible portion of the fire, are produced in the combustion re ...
, thereby trimming itself.


Candle flame

A candle flame is formed because wax vaporizes on burning. A candle flame is widely recognized as having between three and five regions or "zones": * Zone I – this is the non-luminous, lowest, and coolest part of the candle flame. It is located around the base of the wick where there is insufficient oxygen for fuel to burn. Temperatures are around . * Zone II – this is the ''blue zone'', which surrounds the base of the flame. Here the supply of oxygen is plentiful, and the fuel burns clean and blue. It is heat from this zone which causes the wax to melt. Temperatures are around . * Zone III – the ''dark zone'' is a region directly above the wick containing unburnt wax.
Pyrolysis Pyrolysis is a process involving the Bond cleavage, separation of covalent bonds in organic matter by thermal decomposition within an Chemically inert, inert environment without oxygen. Etymology The word ''pyrolysis'' is coined from the Gree ...
takes place here. Temperature is around . *Zone IV – the ''middle'' or ''luminous zone'' is yellow/white and is located above the dark zone. It is the brightest zone, but not the hottest. It is an oxygen-depleted zone with insufficient oxygen to burn all of the wax vapor rising from below it, resulting in only partial combustion. The zone also contains unburnt carbon particles. Temperature is around . * Zone V – The non-luminous ''outer zone'' or ''veil'' surrounds Zone IV. Here, the flame is at its hottest, at around , and complete combustion occurs. It is light blue in color, though most of it is invisible. The main determinant of the height of a candle flame is the diameter of the wick. This is evidenced in tealights where the wick is very thin and the flame is very small. Candles whose main purpose is illumination use a much thicker wick.


History of study

One of
Michael Faraday Michael Faraday (; 22 September 1791 – 25 August 1867) was an English chemist and physicist who contributed to the study of electrochemistry and electromagnetism. His main discoveries include the principles underlying electromagnetic inducti ...
's significant works was '' The Chemical History of a Candle'', where he gives an in-depth analysis of the evolutionary development, workings and science of candles.


Hazards

According to the
National Fire Protection Association The National Fire Protection Association (NFPA) is a U.S.-based international nonprofit organization devoted to eliminating death, injury, property damage, and economic loss due to fire, electrical, and related hazards. , the NFPA claims to have 5 ...
, candles are a leading source of residential fires in the United States with almost 10% of civilian injuries and 6% of fatalities from fire attributed to candles. A candle flame that is longer than its laminar smoke point will emit soot. Proper wick trimming will reduce soot emissions from most candles. The liquid wax is hot and can cause skin burns, but the amount and temperature are generally rather limited and the burns are seldom serious. The best way to avoid getting burned from splashed wax is to use a candle snuffer instead of blowing directly on the flame. A candle snuffer is usually a small metal cup on the end of a long handle. Placing the snuffer over the flame cuts off the oxygen supply. Snuffers were common in the home when candles were the main source of lighting before electric lights were available. Ornate snuffers, often combined with a taper for lighting, are still found in those churches which regularly use large candles. Glass candleholders are sometimes cracked by thermal shock from the candle flame, particularly when the candle burns down to the end. When burning candles in glass holders or jars, users should avoid lighting candles with chipped or cracked containers and discontinue use once a half inch or less of wax remains. A former worry regarding the safety of candles was that a
lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
core was used in the wicks to keep them upright in container candles. Without a stiff core, the wicks of a container candle could sag and drown in the deep wax pool. Concerns rose that the lead in these wicks would vaporize during the burning process, releasing lead vapors – a known health and developmental hazard. Lead core wicks have not been common since the 1970s. Today, most metal-cored wicks use
zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...
or a zinc
alloy An alloy is a mixture of chemical elements of which in most cases at least one is a metal, metallic element, although it is also sometimes used for mixtures of elements; herein only metallic alloys are described. Metallic alloys often have prop ...
, which has become the industry standard. Wicks made from specially treated paper and cotton are also available. Candles emit
volatile organic compound Volatile organic compounds (VOCs) are organic compounds that have a high vapor pressure at room temperature. They are common and exist in a variety of settings and products, not limited to Indoor mold, house mold, Upholstery, upholstered furnitur ...
s into the environment, which releases carbon into the air. The combustion process of lighting a candle includes the release of light, heat, carbon dioxide and water vapor, to fuel the flame. Candle use can be unsafe if fragrances are inhaled at high doses Non-toxic candles have been created as an alternative to prevent these volatile organic compounds from being released into the environment. Candle companies such as "The Plant Project" have created candles that are more environmentally sustainable and better for lung health. These alternatives include non-toxic wax blends, safe fragrances and eco-friendly packaging. Safer candles include candles made from coconut, soy, vegetable, and beeswax. Users who seek the aesthetics of a candle sometimes install an electric flameless candle to avoid the hazards.


Regulation

International markets have developed a range of standards and
regulation Regulation is the management of complex systems according to a set of rules and trends. In systems theory, these types of rules exist in various fields of biology and society, but the term has slightly different meanings according to context. Fo ...
s to ensure compliance, while maintaining and improving
safety Safety is the state of being protected from harm or other danger. Safety can also refer to the control of recognized hazards in order to achieve an acceptable level of risk. Meanings The word 'safety' entered the English language in the 1 ...
, including: * Europe: GPSD, EN 15493, EN 15494, EN 15426, EN 14059, REACH, RAL-GZ 041 Candles (Germany), French Decree 91-1175 * United States: ASTM F2058, ASTM F2179, ASTM F2417, ASTM F2601, ASTM F2326 (all are federal and applies in all 50 states), California Proposition 65 (
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
only),
CONEG The Coalition of Northeastern Governors (CONEG) is a non-partisan organization of seven governors of the Northeastern United States. The organization was founded in 1976 and is headquartered in Washington, D.C. The organization deals with regional i ...
(
New England New England is a region consisting of six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the ...
and New York states only) * China: QB/T 2119 Basic Candle, QB/T 2902 Art Candle, QB/T 2903 Jar Candle, GB/T 22256 Jelly Candle


Accessories


Candle holders

Decorative candleholders, especially those shaped as a pedestal, are called candlesticks; if multiple candle tapers are held, the term '' candelabra'' is also used. The root form of ''
chandelier A chandelier () is an ornamental lighting device, typically with spreading branched supports for multiple lights, designed to be hung from the ceiling. Chandeliers are often ornate, and they were originally designed to hold candles, but now inca ...
'' is from the word for candle, but now often refers to an electric fixture. The word ''chandelier'' is used to describe a hanging fixture designed to hold multiple lights. Other forms of candle holders include the wall-mounted sconces,
lantern A lantern is a source of lighting, often portable. It typically features a protective enclosure for the light sourcehistorically usually a candle, a oil lamp, wick in oil, or a thermoluminescence, thermoluminescent Gas mantle, mesh, and often a ...
s, and girandoles. Many candle holders use a friction-tight socket to keep the candle upright. In this case, a candle that is slightly too wide will not fit in the holder, and a candle that is slightly too narrow will wobble. Candles that are too big can be trimmed to fit with a knife; candles that are too small can be fitted with aluminium foil. Traditionally, the candle and candle holders were made in the same place, so they were appropriately sized, but
international trade International trade is the exchange of capital, goods, and services across international borders or territories because there is a need or want of goods or services. (See: World economy.) In most countries, such trade represents a significan ...
has combined the modern candle with existing holders, which makes the ill-fitting candle more common. This friction-tight socket is only needed for the federals and the tapers. For tea light candles, there is a variety of candle holders, including small glass holders and elaborate multi-candle stands. The same is true for votives. Wall sconces are available for tea light and votive candles. For pillar-type candles, the assortment of candle holders is broad. A fireproof plate, such as a glass plate or small mirror, can be a candle holder for a pillar-style candle. A pedestal of any kind, with the appropriate-sized fireproof top, is another option. A large glass bowl with a large flat bottom and tall mostly vertical curved sides is called a hurricane. The pillar-style candle is placed at the bottom center of the hurricane. A hurricane on a pedestal is sometimes sold as a unit. A bobèche is a drip-catching ring, which may also be affixed to a candle holder, or used independently of one. Bobèches can range from ornate metal or glass to simple plastic, cardboard, or wax paper. Use of paper or plastic bobèches is common at events where candles are distributed to a crowd or audience, such as Christmas carolers or people at other concerts or festivals.


Candle snuffers

Candle snuffers are instruments used to extinguish burning candles by smothering the flame with a small metal cup that is suspended from a long handle, and thus depriving it of oxygen. An older meaning refers to a scissor-like tool used to trim the wick of a candle. With skill, this could be done without extinguishing the flame. The instrument now known as a candle snuffer was formerly called an "extinguisher" or "douter".


Candle followers

These are glass or metal tubes with an internal stricture partway along, which sit around the top of a lit candle. As the candle burns, the wax melts and the follower holds the melted wax in, whilst the stricture rests on the topmost solid portion of wax. Candle followers are often deliberately heavy or weighted to ensure they move down as the candle burns lower, maintaining a seal and preventing wax escape. The purpose of a candle follower is threefold: * To contain the melted wax, making the candle more efficient, avoiding mess, and producing a more even burn. * As a decoration, either due to the ornate nature of the device, or (in the case of a glass follower) through light dispersion or colouration. * If necessary, to shield the flame from wind. Candle followers are often found in churches on altar candles.


Gallery

File:Tutankhamun tomb photographs 5 452.jpg, Object in the tomb of Tutankhamun File:Washington National Cathedral (photo 2).jpg, Candlelight vigil File:Sham' Gardani in Ardabil 2019-09-09 14.jpg, Candles used in Iran in a mourning ceremony File:Sandakan Sabah SamSingKungTemple-22.jpg, Candles used in a Chinese temple File:Cera (46362656605).jpg, Multi-wick candles used in a Sicilian festival File:Woman lighting the candles for the Festival of Lights in India (cropped).jpg, Lighting candles for the Indian festival of
Diwali Diwali (), also called Deepavali (IAST: ''Dīpāvalī'') or Deepawali (IAST: ''Dīpāwalī''), is the Hindu festival of lights, with variations celebrated in other Indian religions such as Jainism and Sikhism. It symbolises the spiritual v ...
File:Gamla Stan, Södermalm, Stockholm, Sweden - panoramio (231).jpg, A candelabra with candles in a Swedish cathedral File:Kerzenpeng1.jpg, Handmade candles File:RamirezLopezCandle02.JPG, A decorative candle in Mexico File:Candle With Gold Stand.jpg, A small ornamental candle with a gold stand


See also

* Candle-making * Candle warmer * Candelabra * Eulachon * Julleuchter * Outdoor candle * Rushlight * Trick candles * Trudon * Unity candle * Yahrzeit candle


References


Bibliography

* * * *


External links

*
National Candle Association
of the U.S.
The Chemical History of a Candle
by Michael Faraday
Association of European Candlemakers(AECM)

European Candle Association (ECA)

Latin American Candle Manufacturers Association (ALAFAVE)

Guide To Candle Safety At Home - Osmology
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