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A candle is an ignitable
wick Wick most often refers to: * Capillary action ("wicking") ** Candle wick, the cord used in a candle or oil lamp ** Solder wick, a copper-braided wire used to desolder electronic contacts Wick or WICK may also refer to: Places and placename ...
embedded in
wax Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to giv ...
, or another flammable solid substance such as
tallow Tallow is a rendered form of beef or mutton fat, primarily made up of triglycerides. In industry, tallow is not strictly defined as beef or mutton fat. In this context, tallow is animal fat that conforms to certain technical criteria, includ ...
, that provides
light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 te ...
, and in some cases, a
fragrance An aroma compound, also known as an odorant, aroma, fragrance or flavoring, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficiently ...
. A candle can also provide
heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...
or a method of keeping
time Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, ...
. A person who makes candles is traditionally known as a chandler. Various devices have been invented to hold candles, from simple tabletop
candlestick A candlestick is a device used to hold a candle in place. Candlesticks have a cup or a spike ("pricket") or both to keep the candle in place. Candlesticks are less frequently called "candleholders". Before the proliferation of electricity, candl ...
s, also known as candle holders, to elaborate candelabra and chandeliers. For a candle to burn, a heat source (commonly a naked flame from a
match A match is a tool for starting a fire. Typically, matches are made of small wooden sticks or stiff paper. One end is coated with a material that can be ignited by friction generated by striking the match against a suitable surface. Wooden matc ...
or
lighter A lighter is a portable device which creates a flame, and can be used to ignite a variety of items, such as cigarettes, gas lighter, fireworks, candles or campfires. It consists of a metal or plastic container filled with a flammable liquid or ...
) 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 the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
in the atmosphere to ignite and form a constant
flame A flame (from Latin '' flamma'') is the visible, gaseous part of a fire. It is caused by a highly exothermic chemical reaction taking place in a thin zone. When flames are hot enough to have ionized gaseous components of sufficient density they ...
. 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, or even in opposition to, any external forces li ...
; the liquefied fuel finally vaporizes to burn within the candle's flame. As the fuel (wax) is melted and burned, the candle becomes shorter. Portions of the wick that are not emitting vaporized fuel are 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. Some wicks require regular trimming with scissors (or a specialized wick trimmer), usually to about one-quarter inch (~0.7 cm), to promote slower, steady burning, and also to prevent smoking. 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 constructed so that it curves over as it burns. This ensures that the end of the wick gets oxygen and is then consumed by
fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. At a certain point in the combustion reaction, called the ignition point, flames a ...
—a self-trimming wick.


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 ...
, from
Old English Old English (, ), 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 was brought to Great Britain by Anglo-Saxon settlers in the mid-5th c ...
and from
Anglo-Norman Anglo-Norman may refer to: *Anglo-Normans, the medieval ruling class in England following the Norman conquest of 1066 * Anglo-Norman language **Anglo-Norman literature * Anglo-Norman England, or Norman England, the period in English history from 10 ...
, both from
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
, from 'to shine'.


History

Prior to the candle, people used
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. Th ...
s in which a lit wick rested in a container of liquid oil.
Romans Roman or Romans most often refers to: *Rome, the capital city of Italy * Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *''Epistle to the Romans'', shortened to ''Romans'', a lette ...
began making true dipped candles from tallow, beginning around 500 BC. European candles of antiquity were made from various forms of natural fat, tallow, and wax. In
Ancient Rome In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 BC ...
, candles were made of tallow due to the prohibitive cost of beeswax. They may have also existed in
Ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean Sea, Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of Classical Antiquity, classical antiquity ( AD 600), th ...
, but imprecise terminology makes it difficult to determine. The earliest surviving candles originated in
Han China The Han dynasty (, ; ) was an imperial dynasty of China (202 BC – 9 AD, 25–220 AD), established by Liu Bang (Emperor Gao) and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–207 BC) and a war ...
around 200 BC. These early Chinese candles were made from whale fat. During the Middle Ages,
tallow Tallow is a rendered form of beef or mutton fat, primarily made up of triglycerides. In industry, tallow is not strictly defined as beef or mutton fat. In this context, tallow is animal fat that conforms to certain technical criteria, includ ...
candles were most commonly used. By the 13th century, candle making had become a guild craft in England and France. 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.
Beeswax Beeswax (''cera alba'') is a natural wax produced by honey bees of the genus ''Apis''. The wax is formed into scales by eight wax-producing glands in the abdominal segments of worker bees, which discard it in or at the hive. The hive work ...
, compared to animal-based tallow, burned cleanly, without smoky flame. Beeswax candles were expensive, and relatively few people could afford to burn them in their homes in medieval Europe. However, they were widely used for church ceremonies. In the Middle East, during the
Abbasid The Abbasid Caliphate ( or ; ar, الْخِلَافَةُ الْعَبَّاسِيَّة, ') was the third caliphate to succeed the Islamic prophet Muhammad. It was founded by a dynasty descended from Muhammad's uncle, Abbas ibn Abdul-Muttalib ...
and
Fatimid The Fatimid Caliphate was an Ismaili Shi'a caliphate extant from the tenth to the twelfth centuries AD. Spanning a large area of North Africa, it ranged from the Atlantic Ocean in the west to the Red Sea in the east. The Fatimids, a dyna ...
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 ''Tounsi'' french: Tunisois , population_note = , population_urban = , population_metro = 2658816 , population_density_km2 = , timezone1 = CET , utc_offset1 ...
. As in Europe, these candles were fairly expensive, and most commoners used oil lamps instead. Elites, though, could afford to spend large sums on expensive candles. For example, the Abbasid caliph al-Mutawakkil spent 1.2 million silver dirhams 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 during the 1500s and 1600s. However, candle makers had a relatively low social position in Safavid Iran, comparable to
barber A barber is a person whose occupation is mainly to cut, dress, groom, style and shave men's and boys' hair or beards. A barber's place of work is known as a "barbershop" or a "barber's". Barbershops are also places of social interaction and publi ...
s,
bathhouse Public baths originated when most people in population centers did not have access to private bathing facilities. Though termed "public", they have often been restricted according to gender, religious affiliation, personal membership, and other cr ...
workers, fortune tellers, bricklayers, and
porter Porter may refer to: Companies * Porter Airlines, Canadian regional airline based in Toronto * Porter Chemical Company, a defunct U.S. toy manufacturer of chemistry sets * Porter Motor Company, defunct U.S. car manufacturer * H.K. Porter, Inc., ...
s. In the 18th and 19th centuries, spermaceti, a waxy substance produced by the sperm whale, was used to produce a superior candle that burned longer, brighter and gave off no offensive smell. Later in the 18th century,
colza oil Close-up of canola blooms Canola flower Rapeseed oil is one of the oldest known vegetable oils. There are both edible and industrial forms produced from rapeseed, the seed of several cultivars of the plant family Brassicaceae. Historically, ...
and
rapeseed Rapeseed (''Brassica napus ''subsp.'' napus''), also known as rape, or oilseed rape, is a bright-yellow flowering member of the family Brassicaceae (mustard or cabbage family), cultivated mainly for its oil-rich seed, which naturally contains a ...
oil came into use as much cheaper substitutes.


Modern era

The manufacture of candles became an industrialized mass market in the mid 19th century. In 1834, Joseph Morgan, a
pewter Pewter () is a malleable metal alloy consisting of tin (85–99%), antimony (approximately 5–10%), copper (2%), bismuth, and sometimes silver. Copper and antimony (and in antiquity lead) act as hardeners, but lead may be used in lower grades ...
er from
Manchester Manchester () is a city in Greater Manchester, England. It had a population of 552,000 in 2021. It is bordered by the Cheshire Plain to the south, the Pennines to the north and east, and the neighbouring city of Salford to the west. The t ...
, 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. Candlemakers also began to fashion wicks out of tightly braided (rather than simply twisted) strands of
cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor pe ...
. This technique makes wicks curl over as they burn, maintaining the height of the wick and therefore the flame. Because much of the excess wick is incinerated, these are referred to as "self-trimming" or "self-consuming" wicks. 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 begins to ...
from coal and oil shales at
Bathgate Bathgate ( sco, Bathket or , gd, Both Chèit) is a town in West Lothian, Scotland, west of Livingston, Scotland, Livingston and adjacent to the M8 motorway (Scotland), M8 motorway. Nearby towns are Armadale, West Lothian, Armadale, Blackburn, ...
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 Tallow is a rendered form of beef or mutton fat, primarily made up of triglycerides. In industry, tallow is not strictly defined as beef or mutton fat. In this context, tallow is animal fat that conforms to certain technical criteria, includ ...
candles. By the end of the 19th century, candles were made from paraffin wax and stearic acid. By the late 19th century,
Price's Candles Price's Patent Candles, founded in 1830, is an importer and retailer of candles. The firm is headquartered in Bedford in England, and holds the Royal Warrant for the supply of candles. It is today the largest candle supplier in the United Kin ...
, 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, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...
and lamps and the 1879 invention of the
incandescent light bulb An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxid ...
. From this point on, candles came to be marketed as more of a decorative item.


Use

Before the invention of electric lighting, 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, for emergency lighting during electrical
power failure A power outage (also called a powercut, a power out, a power failure, a power blackout, a power loss, or a blackout) is the loss of the electrical power network supply to an end user. There are many causes of power failures in an electricity ...
s, and for religious or ritual purposes. 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, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identi ...
and the ensuring 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 continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, ...
. The candle designed for this purpose might have time measurements, usually in hours, marked along the wax. The
Song dynasty The Song dynasty (; ; 960–1279) was an imperial dynasty of China that began in 960 and lasted until 1279. The dynasty was founded by Emperor Taizu of Song following his usurpation of the throne of the Later Zhou. The Song conquered the rest ...
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. 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 An Advent candle is a candle marked with the days of December up to Christmas Eve. It is typically used in a household rather than a church setting: each day in December the candle is burnt down a little more, to the mark for the day, to show t ...
'', 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 church. It is traditionally a Lutheran practice, although it has spread to many other ...
.


Components


Wax

For most of recorded history candles were made from
tallow Tallow is a rendered form of beef or mutton fat, primarily made up of triglycerides. In industry, tallow is not strictly defined as beef or mutton fat. In this context, tallow is animal fat that conforms to certain technical criteria, includ ...
(rendered from beef or mutton-fat) or
beeswax Beeswax (''cera alba'') is a natural wax produced by honey bees of the genus ''Apis''. The wax is formed into scales by eight wax-producing glands in the abdominal segments of worker bees, which discard it in or at the hive. The hive work ...
. From the mid 1800s, they were also made from spermaceti, a waxy substance derived from the Sperm whale, which in turn spurred demand for the substance. Candles were also made from stearin (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 begins to ...
, a byproduct of
petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...
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 Microcrystalline waxes are a type of wax produced by de-oiling petrolatum, as part of the petroleum refining process. In contrast to the more familiar paraffin wax which contains mostly unbranched alkanes, microcrystalline wax contains a higher p ...
,
beeswax Beeswax (''cera alba'') is a natural wax produced by honey bees of the genus ''Apis''. The wax is formed into scales by eight wax-producing glands in the abdominal segments of worker bees, which discard it in or at the hive. The hive work ...
(a byproduct of honey collection),
gel A gel is a semi-solid that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state, although the liquid phase may still dif ...
(a mixture of
polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
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 (; pt, carnaúba ), 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 ...
,
bayberry ''Myrica'' is a genus of about 35–50 species of small trees and shrubs in the family Myricaceae, order Fagales. The genus has a wide distribution, including Africa, Asia, Europe, North America and South America, and missing only from Australi ...
, or soybean wax). The size of the flame and corresponding rate of burning is controlled largely by the
candle wick A candle wick is usually a braided cotton that holds the flame of an oil lamp or candle. A candle wick works by capillary action, conveying ("wicking") the fuel to the flame. When the liquid fuel, typically melted candle wax, reaches the fla ...
. 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 Extrusion is a manufacturing process used to make pipes, hoses, drinking straws, curtain tracks, rods, and fibre. The granules melt into a liquid which is forced through a die, forming a long 'tube like' shape. The shape of the die determines the sh ...
. 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 oils or
aniline Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile starti ...
-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, or even in opposition to, any external forces li ...
, drawing ("wicking") the melted wax or fuel up to the flame. When the liquid fuel reaches the flame, it
vaporize Vaporization (or vaporisation) of an element or compound is a phase transition from the liquid phase to vapor. There are two types of vaporization: evaporation and boiling. Evaporation is a surface phenomenon, whereas boiling is a bulk phenom ...
s 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 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, or even in opposition to, any external forces li ...
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 form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., w ...
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 chemical 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, although it does not form hydrates. It is ...
and
ammonium sulfate Ammonium sulfate (American English and international scientific usage; ammonium sulphate in British English); (NH4)2SO4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen a ...
.


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 Luminous efficacy is a measure of how well a light source produces visible light. It is the ratio of luminous flux to power, measured in lumens per watt in the International System of Units (SI). Depending on context, the power can be either the ...
of about 0.16 lumens per watt (luminous efficacy of a source) – almost a hundred times lower than an
incandescent light bulb An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxid ...
. If a 1 
candela The candela ( or ; 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 t ...
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 human e ...
of a typical candle is approximately one
candela The candela ( or ; 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 t ...
. The SI unit, candela, was in fact based on an older unit called the ''
candlepower Candlepower (abbreviated as cp or CP) is a unit of measurement for luminous intensity. It expresses levels of light intensity relative to the light emitted by a candle of specific size and constituents. The historical candlepower is equal to 0.981 ...
'', 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 Soot ( ) is a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons. It is more properly restricted to the product of the gas-phase combustion process but is commonly extended to include the residual pyrolysed ...
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 Color temperature is the color of light emitted by an idealized opaque, non-reflective body at a particular temperature measured in kelvins. The color temperature scale is used to categorize the color of light emitted by other light sources ...
is approximately 1,000 K.


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 The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''py ...
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
tealight A tealight (also tea-light, tea light, tea candle, or informally tea lite, t-lite or t-candle) is a candle in a thin metal or plastic cup so that the candle can liquefy completely while lit. They are typically small, circular, usually wider than ...
s 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 scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic inducti ...
's significant works was ''
The Chemical History of a Candle ''The Chemical History of a Candle'' was the title of a series of six lectures on the chemistry and physics of flames given by Michael Faraday at the Royal Institution in 1848, as part of the series of Christmas lectures for young people found ...
'', where he gives an in-depth analysis of the evolutionary development, workings and science of candles.


Hazards

According to the National Fire Protection Association, 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 Soot ( ) is a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons. It is more properly restricted to the product of the gas-phase combustion process but is commonly extended to include the residual pyrolysed ...
. 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 A candle snuffer, candle extinguisher, or douter is an instrument used to extinguish burning candles, consisting of a small cone at the end of a handle. The use of a snuffer helps to avoid problems associated with blowing hot wax and it avoids ...
instead of blowing 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 candle-holders 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 stop 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 with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
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 with the symbol Zn and atomic number 30. Zinc 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 periodi ...
or a zinc
alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductilit ...
, which has become the industry standard. Wicks made from specially treated paper and cotton are also available. Candles emit volatile organic compounds 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 Flameless candles are an electronic alternative to traditional wick candles. They are typically utilized as aesthetic lighting devices and come in a variety of shapes, colors and sizes. A flame-effect lightbulb contains multiple small light-emittin ...
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 "safe", the condition 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 There are two slightly dif ...
, 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 state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
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 ...
(
New England New England is a region comprising 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 Can ...
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
candlestick A candlestick is a device used to hold a candle in place. Candlesticks have a cup or a spike ("pricket") or both to keep the candle in place. Candlesticks are less frequently called "candleholders". Before the proliferation of electricity, candl ...
s; if multiple candle tapers are held, the term ''candelabrum'' is also used. The root form of '' chandelier'' is from the word for candle, but now usually refers to an electric fixture. The word ''chandelier'' is sometimes now used to describe a hanging fixture designed to hold multiple tapers. 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 significant ...
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 A votive offering or votive deposit is one or more objects displayed or deposited, without the intention of recovery or use, in a sacred place for religious purposes. Such items are a feature of modern and ancient societies and are generally ...
. 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 A bobèche is a cup or ring at the top of a candlestick A candlestick is a device used to hold a candle in place. Candlesticks have a cup or a spike ("pricket") or both to keep the candle in place. Candlesticks are less frequently called "can ...
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 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 candle Altar candles are candles set on or near altars for religious ceremonies. Various religions have regulations or traditions regarding the number and type of candles used, and when they are lit or extinguished, for example during the liturgies. ...
s.


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".


See also

*
Candle-making Candle making was developed independently in many places throughout history. Dipped candles made from tallow were made by the Romans beginning about 1000 BCE. Evidence for candles made from whale fat in China dates back to the Qin Dynasty (221 ...
*
Candle warmer A candle warmer is an electric warmer that melts a candle or scented wax to release its scent. The candle warmer shown is intended to be used with jar candles or candles in cups, not with taper candles or candles without containers large enough ...
* Candelabra *
Julleuchter Julleuchter (; "Yule lantern") or ''Turmleuchter'' ("tower lantern") are modern terms used to describe a type of earthenware candle-holder originating in 16th-century Sweden, later redesigned and manufactured in Nazi Germany. Swedish artefact ...
*
Outdoor candle An outdoor candle, which is also known a pitch torch or a garden candle (, , fi, soihtukynttilä) is a large (usually 10 cm wide) tealight-like candle that are lit outside. They are commonly found in Scandinavia, and are used as an ou ...
*
Rushlight A rushlight is a type of candle or miniature torch formed by soaking the dried pith of the rush plant in fat or grease. For several centuries, rushlights were a common source of artificial light for poor people throughout the British Isles. The ...
* Singing candle * Trick candles * Trudon *
Unity candle Unity may refer to: Buildings * Unity Building, Oregon, Illinois, US; a historic building * Unity Building (Chicago), Illinois, US; a skyscraper * Unity Buildings, Liverpool, UK; two buildings in England * Unity Chapel, Wyoming, Wisconsin, US; ...
*
Yahrzeit candle A yahrzeit candle, also spelled yahrtzeit candle or called a memorial candle, ( he, נר נשמה, ''ner neshama'', meaning "soul candle"; yi, יאָרצײַט ליכט , meaning "anniversary candle") is a type of candle that is lit in memo ...


References


External links

*
National Candle Association
of the
U.S. The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

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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