Glossary of Most Used Candle Terms

Additive
A substance blended with wax to enhance its burning qualities or alter its properties. Additives may include vybar, stearic acid, or UV inhibitor to name a few.

Afterglow ( or Aftersmoke ) 
The light emitted after removal of an energy source. A wick may tend to “glow” and burn down slightly even after it has been extinguished.When the wick continues to smoke or glow after you have blown out the flame.

Aroma Compound 

A chemical chemical that gives off a fragrance or odour, typically used in fragrance oils. Not to be confused with aromatic compounds, which contain a specific chemical sub-structure and have no particular association with the fragrance industry

Bridging

The term used when a burning wick curls to such an extent that the tip of the wick makes contact with the surface of the melt pool

Burn Cycle

The act of burning a candle for 4 hours and blowing it out to let it cool. This process is used for evaluating wick performance and calculating burn time.

Burn Rate
The amount of wax consumed per hour in grams. Also known as the hourly burn rate, this is the rate at which a candle burns, typically measured in grams per hour (g/h). To calculate the burn rate, a candle is weighed at the start of a burning period, then weighed again at the end of the burning period. The difference in weight represents the quantity of wax consumed. This weight is divided by the number of hours that the candle has burned to give the burn rate of the candle in grams per hour. For example, a candle that consumes 16.8g of wax over a 4-hour burning period will have a burn rate of 16.84 = 4.2

Burn time 

The amount of time it takes for the wax in a candle to be consumed completely.lso known as the hourly burn rate, this is the rate at which a candle burns, typically measured in grams per hour (g/h).

Burn Test 

Informal term for process used to assess the burning performance of a candle

Burn Test Cycle

The total time of a burning period and the pause after the burning period. The process of burning a full candle from start to finish consists of a series of burn test cycles.

Burning Period 

The length of time between lighting a candle and extinguishing the flame

Cavity ( or Sink Hole ) 

Cavity that is formed when a wax hardens and contracts.A gap or void that is formed inside or on the surface of a candle as the wax contracts during the cooling and curing process. air pockets that are trapped in the wax while it is cooling.

CLP 

General term for the label that displays the pictograms, signal words and standard statements for hazards etc. for candles and diffusers. The label is a legal requirement under the Classification, Labelling and Packaging (CLP) Regulation ((EC) No 1272/2008). The CLP label must be visible at the point of purchase, and it must be present on the box if the product is packed.

Clubbing ( or Mushrooming ) 

Seen at the top of a candle wick, this is a small amount of carbon caused by incomplete combustion. Often the wrong wick size, wax additives or fragrance contribute to this problem.

Cold Throw

Term used to describe the strength of fragrance before a candle has been burned for the first time. This evaluation depends on the type of wax you are using. For paraffin after 24h, for vegetal waxes like soy or soy blends after 48h to two weeks, for coconut blends after 48hrs.

Container candle
Any candle poured directly into the container from which it will be burned.

Core
Refers to the interior of a candle.  Also used to reference the inner material of a candle wick (may include zinc, cotton or paper).

Coreless
Used to refer to wicks, this indicates there is no core material.

Crystallisation  The process where a poured candle mixture changes from a liquid to a solid mass which then “cures” to a stable form. See also curing time.

Curing time ( Cure)
To allow a candle to set, or age, to help enhance the fragrance.The period of time between pouring the candle and the candle reaching a state where it can be lit to give optimum performance. The curing time will differ for each wax/fragrance oil mixture

Diameter
The measurement of a candle, container or mold at its widest point.

Double boiler
Two nested pans with water in the lower one, designed to allow slow, even heating.

Double scenting
Adding 65 ml of fragrance per kg of wax.

Essential oil
An oil derived from a natural substance (plant material, flowers, leaves, wood, grass)An oil obtained by distillation of plant extracts, intended to capture the characteristic fragrance or “essence” of the plant. Essential oils are often marketed as blends of different oils.

Fire Test Safety 

An informal term used for the series of tests and measurements performed on a candle to ensure that it meets the requirements of BS EN 15493:2019 (Candles - Specification for Fire Safety)

Flame height

The distance between the base of the flame and the top of the flame

Flashpoint

The temperature at which a substance can ignite if it comes in contact with an open flame or spark.The flash point of a liquid (e.g., a fragrance oil) is the temperature at which the liquid gives off enough vapour that could cause it to ignite (althoug briefly) if exposed to a source of ignition.

Floater (floating candle)
A shallow candle with a significantly tapered base that will float in water.

Fragrance Content 
Term is defined as the percentage of fragrance oil relative to the total mass of the candle formula.  So, in a 220g (net) candle, a fragrance content of 10% would mean the candle contained 22g of oil.  The remaining 198g would be wax/base. More info here.

Fragrance Load 
Term is defined as the percentage of fragrance oil relative to the mass of wax only.  So, in a 220g (net) candle, a fragrance load of 10% would mean the candle contained 20g of oil.  The remaining 200g would be wax/base. More info here.

Fragrance oil
A blend of synthetic and/or natural components used to create scented oil.

Fragrance Notes 

A term used to describe the properties of a fragrance in words. There are three types of fragrance notes: Top Notes – these are the citrus or fruity notes. Top notes are volatile and give a powerful first impression of a fragrance. Middle Notes – also known as “heart” notes, these are floral, fruity or spicy components of a fragrance. Base Notes – these are the woody or musky notes that tend to hang around for a while

Frosting
White crystalline structure that forms on the surface of natural waxes such as soy. Also referred to as bloom. The “frosting” often referred to in candle-making is an example of “polymorphism”, where the solid mass of wax and fragrance oil changes into a different crystal form over time, causing a frost-like effect on the surface of the candleThis commonly occurs with soy wax candles. You can reduce frosting by pouring your candles between 43-46 degrees.

Gel Candle
A usually translucent or clear candle that is made from a mineral oil based product.

Glass Adhesion
Also known as Wet Spots or Delamination/Separation. This is when the wax pulls away from the glass. Very common with container candles.A term used to describe how well a particular wax/fragrance mixture adheres to a candle glass. As wax cools, it contracts and pulls away from the glass leaving visible gaps on the inside of the glass. Plant waxes generally have better glass than mineral waxes(eg paraffin)

Gutter
Excess melted wax running down the outside of a self-supporting candle.

Hang-Up
Unburned wax that remains on the wall of jar candles when the candle has expired.

Hot Throw
Term used to describe the strength of fragrance while a candle is burning. This evaluation is typically done after the candle has been burning for at least 2 hours but no more than 4.

Hurricane Candle

An outer shell of wax with a high melt point that may be decorated and is not intended for burning. There will be an inner candle that can be burned and/or replaced.

IFRA  International Fragrance Association

IFRA Statement

Informal name for the “Certificate of Conformity to IFRA Standards”. The IFRA Statement lists the maximum permitted levels of use of each fragrance oil in different product categories, e.g. candles, soaps, lotions

Jump Lines (Chatter Marks)
The unintended visible lines on the sides of a container or pillar candle. These are often caused by pouring the wax at too low of a temperature or pouring into a cold container. When this occurs the wax is congealing immediately and starting to set as more wax is being poured on top of it.Also known as jump marks, these are a series of horizontal lines that can be seen on the inside of a clear candle glass when higher-melting waxes (typically mineral wax) have been used to pour a candle without pre-heating the candle glass. They are formed as the liquid wax solidifies on the cold surface of the glass.

Liquid Dye or Solid Dye
Colorants that are used to give color to wax.

Melt Point
The temperature at which melting wax gets hot enough to turn from a solid into a liquid.

Melt Pool or Full Melt Pool 
This is the liquid layer of wax that forms as the candle burns. When the melt pool in a container candle covers the entire surface of the candle.

Mixing Temperature
The temperature to add color and fragrance to melted wax, ideally this will be 65ºC regardless of wax being used. Informal term used to describe the recommended temperature for mixing fragrance oil or dye with candle wax to ensure that the fragrance oil or dye will dissolve in the wax

Mold plug
Small cone shaped rubber pieces used to close the hole in the bottom of a mold.

Mold release
An agent used to coat the inside of a mold to make removing the candle easier.

Mold sealer
A clay-like substance use to seal the hole on the bottom of a mold, used to block the extra space left around the wick on the outside of the mold.

Mottling
A surface effect in wax that has a snowflake type appearance.

MSDS (Material Safety Data Sheet)
Product safety information sheets prepared by manufacturers and marketers of products.

Mushrooming
Carbon build up on the tip of a wick after burning.

Mushrooming ( or Clubbing ) 
Seen at the top of a candle wick, this is a small amount of carbon caused by incomplete combustion. Often the wrong wick size, wax additives or fragrance contribute to this problem.

Natural wax

A term often used to refer to the mixture plant wax with mineral wax 

Nature Identical 

Used to describe essential oil ingredients that have been made in laboratories rather than extracted from plants. They are chemically identical to the actual molecules found in the plant-based essential oil, but the use of synthetic components ensures batch reproducibility and consistency

Neck
The vertical shaft of a wick tab that secures the tab to the wick. Lengths of wick tab necks can vary.

Opaque
Not transmitting or reflecting light; impenetrable to sight.

Out of Bottle
The first evaluation of a fragrance happens as soon as you open the bottle, this is referred to as out of bottle or OOB evaluation.

Overdip
Coating a finished candle with an alternate wax for color or other effects.

Overwicked

When the wick in a candle causes a burn rate that is higher than expected or desired, the candle is said to be overwicked. See also underwicked

Palm wax
A resinous wax made from a wax palm. A clean burning wax that is a natural alternative to paraffin.

Paraffin wax
Made of refined petroleum; most commonly used wax in candle making.

Pillar candle
A candle made in a mold and meant to be free-standing.

Pouring Temperature
Temperature to pour the fragranced/colored wax into the container or mold.

Power Burn
The act of burning a candle for longer than 4 hours, often 8+ hours. This can be dangerous and it is not recommended.

Pull away  See glass adhesion

Relief holes
Holes poked in candles to release air pockets that can form as wax cools to prepare for a second pour.

Repour or double pour 
The action of filling the cavity left after wax has completely cooled to make the top of the candle level.A candle pouring technique in which a container candle is poured in two stages. Typically, the first pour will fill 70-90% of the candle. After cooling, when the wax has contracted, the second pour fills the candle to the desired level.

Safety Data Sheet  ( SDS )

A document that provides safety information about a substance.

Secondary Ignition 

A flame other than that on the actual wick(s) on the candle

Scent Load
Amount of fragrance a wax will hold; usually stated in a percentage.

Scent oil
See Fragrance oil.

Scent throw
The fragrance emitted by a candle. (See also cold and hot throw)

Second pour
See Repour

Secondary Ignition

A flame other than that on the actual wick(s) on the candle

Single pour wax
A wax that does not shrink enough to require a second pour.

Sink hole
Cavity that is formed when a wax hardens and contracts.A gap or void that is formed inside or on the surface of a candle as the wax contracts during the cooling and curing process. air pockets that are trapped in the wax while it is cooling.

Smelly Jelly
Product made from water crystals, used as an air freshener and not intended to be heated.

Soy wax
An all natural wax made of soy beans.  A clean burning wax that is a natural alternative to paraffin.

Soot 

Black powdery carbon deposit caused by incomplete combustion of candle wax and fragrance oils.

Soot Test 

An informal term used for the testing of a candles using specialised soot testing apparatus to ensure that it meets the requirements of BS EN 15426:2018 (Candles - Specification for Sooting Behaviour ) 

Sustainer

The metal support used to secure the wick to the base of the candle glass.

Stearic acid
Used to increase opaqueness, slow burning, and harden wax.

Synthetic oil
Fragrance oil that is man-made.Fragrance oils that are developed by professional perfumers using organic chemical building blocks.

Sweating 

Leaching of fragrance oil (or oil from the wax blend) from the candle onto the surface of the wax.

Taper

A tall, thin candle that becomes more slender at the burning end.  A candle holder must be used with this type candle.

Tart Burner
A device that has a votive or tealight in a lower compartment with an open cupped area on top where a tart can be heated.

Tart
A small portion of scented wax used in a tart burner.  Can be made in various shapes

Technical Data Sheet ( TDS ) 

Document provided by the supplier of a product or raw material that gives useful technical information about the product. While a Safety Data Sheet is intended to give safety information about a product, the role of a Technical Data Sheet is to advise the user on the specification of the product such as its physical properties, uses or origin.

Tealight
A small, self-contained candle usually poured in a tin cup 

Transition Temperature
The temperature or temperature range at which a wax cooling from the liquid to the solid state converts from non-crystalline form to a crystalline one.

Triple Scent
Adding 98 ml of fragrance per Kg of wax.

Tunneling
When the wick burns straight down the center of a candle without creating a full melt pool. This is most often caused by the wick being too small for the container .This is an extreme form of hang-up, indicating that the candle may be under-wicked or that the wick is incompatible with the wax/fragrance oil mixture

Underwicked

When the wick in a candle causes a burn rate that is lower than expected or desired, the candle is said to be underwicked. See also overwicked.

UV stabilizer
An additive used to prevent fading when a candle is exposed to UV rays or fluorescent lighting.

Viscosity
Viscosity is a fluid's ability to resist flow. Ketchup or honey have a high viscosity. Milk or juice has a low viscosity.

Votive candle
A small candle that requires burning in a votive holder; designed to liquefy completely

Vybar
A polymer used primarily to aid in fragrance oil retention, also increases opacity and enhances color.  A modern alternative to stearic acid.

Water bath
A container of water used to accelerate the cooling process of a candle; cool water is usually used.

Wick
Material that delivers fuel to the flame in a candle.The part of a candle that is lit, creating a flame that melts more wax. The liquid wax is then drawn back into the wick via capillary action to fuel the flame and continue the burning process.

Wick Wax The wax that is used to coat the candle wick

Wick bar

A small metal bar used when making candles to stabilize a wick at the top of a candle

Wick clip assembly
A precut length of wick with a wick tab already crimped in place.

Wick Down
To use a wick one size smaller but within the same series. For example: going from an Stabilo 10 to Stabilo 8.

Wick pin
Takes the place of the wick while pouring votive or pillar candles.  It is removed when the candle is completely cool, and a wick is inserted in its place.

Wick Stickum 

The double-sided sticky pad that is used to secure a wick sustainer to a candle glass.

Wick tab
A flat metal disc with a small hole in the center for a wick; holds the wick at the bottom of a candle.

Wick Up
To use a wick one size larger within the same series. For example: going from an Stabilo 8 to Stabilo 10

Wick Yield 

A measure of the thickness of a candle wick. The units used are grams per metre (g/m) or metres per kilogram (m/kg). These values refer to the unwaxed wick. For example, a wick with a yield value of 1.50 g/m means that a 1 metre length of raw wick weighs 1.50 grams. The m/kg system is basically an "inverted" version of the above. A wick with a yield value of 665m/kg means that 1 kg of raw wick will stretch to a length of 665 metres. Learn more here

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