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Joint Presentation for Alafave Workshop 2005
Alafave WorkshopBurning of Candle Blends
Buenos Aires, July 5 – 8, 2005
Marc Prüsmann – Sasol Wax, C.A.Steven West – Wedo
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Overview Introduction
– Definition of a candle / The system candle– Quality parameters of a burning candle
Candle blends– Raw materials and their characteristics – Blends– Parameters which influence the combustion process– Importance of purity / Quality requirements
Wicks– Different raw materials require different wicks– Wick quality – raw materials, chemical treatment, braiding– Factors influencing wick selection– The correct position
Soot testing Conclusion
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Introduction − Definition of a Candle
“One or more combustible wicks supported by a material that constitutes a fuel, which is solid, semisolid or quasi-rigid at room temperature (20 - 30 °C). It can also contain additives, which are used for colour, odour, stability, or to modify the burning characteristics; the combined function of which is to sustain a light- producing flame.“ (ASTM Definition)
Types of candlesCandle / Light
Burning Outdoors Burning Indoors
Fuel in container Fuel free standing
Grave light Others
Fuel in container Fuel free standing
Container light Votiv / Tealight Cylindrical Non Cylindrical Floating
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The system candle
Burning Properties
Container & Jars Fragrances Colours
Production Process Wicks Lacquers
Specialized Products
Blends
Paraffin WaxesSoft HardParaffin Waxes Paraffin Waxes Waxes35 - 40 °C 45 - 60 °C 70 - 100 °C
PolymersBeeswaxesAdditives
StearicAcidFats
6Quality parameters of a burning candle
Visible– Drip-fastness– Uniformity of burning– Appropriate flame– Burning bowl– No visible smoking / sooting
Non visible – Development of harmful
substances
Candle Blends
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0
1
2
3
4
5
6
7
8
9
10
C18
C19
C20
C21
C22
C23
C24
C25
C26
C27
C28
C29
C30
C31
C32
C33
C34
C35
C36
C37
C38
C39
C40
C41
C42
C43
C44
n-alkanes75,5%iso-alkanes24,5%
Raw materials used for candle production
There is no such thing as ONE paraffin, ONE stearic acid or ONE vegetable wax. These terms stand for a whole group of substances each, and in any of these groups you can find a variety of species with many different characteristics.
Raw materials used as candle fuels
90%
2%1%1%6%
Paraffin WaxStearic AcidBeeswaxFatsOthers
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Characteristics of Candle Fuels
All processes ofcandle manufacturing
drawing, dipping, pressing,pouring, extrusion
Soft,ductile,
hard
Saturated linear andbranched as well ascyclic hydrocarbons
Petroleum, coal,natural gas
Paraffin wax
Pouring,pressing
Hard,brittle
Mixture of fatty acids(palmatic acid /
stearic acid)
Hardened oils and fats ofvegetable andanimal origin
Stearic acid
Pouring(without blending)
Sticky,kneadable,
ductile
Wax esterswax alcohols
wax acids
Metabolite of honey bees
Beeswax
Pouring
Hard toductile
at low melting point
Mixture of triglyceridesand fatty acids
Hardened oils and fats ofvegetable andanimal origin
Hardened fats
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Why not one blend? Factors influencing the
selection of a blend– Production process– Different uses, purposes,
shapes, designs, sizes of candles
– Climatic and ambient conditions in which the candle is produced and used.
– Raw material– Cost considerations
11Paraffin wax blends used for candle productionApplication Typical paraffin
wax / data Properties required
Jar filling Complex special blend CP: 40 – 55 °C Pen (25 °C): > 50 1/10 mm
Low shrinkage, good wall adhesion, defined melting and burning
Powder pressing (Tealights)
CP: 50 – 54 °C Oil: max. 1.5% Pen (25 °C): 20 – 35 1/10 mm
Adhesion to powder drum, no lumping of powder, transport, bonding
Molding CP: 58 – 64 °C Oil: max. 0.5% Pen (25 °C): max. 18 1/10 mm
Good radial contraction, detachment from walls homogeneous crystallization
Extrusion CP: 58 – 64 °C Oil: max. 0.8% Pen (25 °C): max. 20 1/10 mm
Plasticity, resistance to bending, good bonding, smooth surface
Overdipping Complex special blend, CP: 58 – 62 °C Pen (25 °C): 12 – 18 1/10 mm Visc. (100 °C): 5 – 15 mm²/s
Homogeneous film and color distribution, opacity, smooth surface, adhesion to core, stability
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Combustion process 1. Melting of the fuel 2. Transport of the fuel by
the capillary action of the wick
3. Conversion of the liquid fuel into gas
4. Thermal decomposition (pyrolysis) of the fuel
5. Oxidisation of the pyrolysis products
1400 °C
1000 °C
1200 °C
800 °C
Temperatures in the perfect flame
13How do the characteristics of the candle fuel influence the burning process?
Congealing point / Melting curve / Heat conductivity
– Burning pool Viscosity / Enthalpy of evaporation
– Fuel supply by the wick Combustion reaction /
Enthalpy of burning process– Flame temperature– Demand of oxygen
Chemical reactivity– Interaction with wick and other
blend components Presence of impurities
– Formation of undesired, hazardous combustion products
Flash point– Directly safety relevant
0,0
2,0
4,0
6,0
8,0
10,0
12,0
14,0
70 75 80 85 90 95 100 105Temperature in °C
Kin
emat
ic V
isco
sity
in m
m²/s
Paraffin Wax 52/54 °CParaffin Wax 56/58 °CParaffin Wax 58/60 °COverdipping WaxMicro Wax
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26,3°C
104,7°C
40
60
80
100
93,9°C
78,6°C
71,8°C64,1°C59,7°C
60,8°C
59,0°C73,0°C
52,2°C
26,3°C
104,7°C
40
60
80
100
93,9°C
78,6°C
71,8°C64,1°C59,7°C
60,8°C
59,0°C73,0°C
52,2°C
Stearic Acid Jar Wax Paraffin Wax 62/64
Gel Wax BeeswaxParaffin Wax 52/54
Stearic Acid Paraffin Wax 52/54
Temperatures in the burning pool
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Raw materials and their characteristics
Paraffin wax– Softening approx. 15 °C
below melting point– Separation (sweating) of
components with lower congealing point
– Soft edge Stearin
– Defined melting point between 52 °C and 60 °C
– Softening and melting point are almost identical
– Dry pool
27,3°C
55,0°C
30
35
40
45
50
55
28,0°C
41,9°C
50,8°C
51,7°C
27,9°C
16Other raw materials and their characteristics
Microcrystalline waxes– Congealing point 65 – 85 °C– Viscosity (100 °C) 8 – 10 mm/s²
Synthetic paraffin waxes– High congealing point 75 – 110 °C– Viscosity relatively low at high
temperatures Polyethylene waxes / Copolymers
– High cloud point– High viscosity
Vaseline / Petrolatum– High content of branched and
cyclic hydrocarbons Fragrances
– Flash point 50 – 100 °C– Possible chemical interaction with
other components of the candle Color preparations
– May contain high content of pigments and high-melt additives
17Importance of the purity of the candle fuel and the additives
There is no non-sooting candle fuel!
The flame will emit soot if the generated energy is insufficient to heat the carbon particles above 1,000 °C.
Minimize / eliminate the emission of undesired and hazardous combustion products by selecting the correct raw materials (apart from the right relation of the wick to the candle).
Avoid unrefined and non-sufficiently hydrogenated (slack) waxes as these contain unsaturated and/or aromatic hydrocarbons and sulfur– Unfavorable carbon/hydrogen
ratio– Favor the formation of soot
and/or have a very high tendency to release soot.
– Production of PAH– Release of undesirable sulfur
oxides whilst the candle is burning.
Avoid “leaded wicks”– Lead compounds can be
released into the air of a room.
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The European Quality Mark Candles has established stringent quality requirements for paraffin waxes.– Color index– Odor– Ash content– Aromatic polycyclic
hydrocarbons– Sulfur content– UV stability
Quality requirements candle blendSimilar purity criteria have been established for:– Stearic acid– Beeswax– Wicks– Dyes– Lacquers– Fragrances
In addition, other commonly used raw materials are to be specified soon:– Fats– Microcrystalline waxes
Wicks
20Different blends often require different wicks
Basic Example
2 dinner candles both 22 mm Ø
Paraffin Wax FW 3x10 SU
Stearic AcidFW 3x15 STP1. 50% more
threads2. Different
chem.treatment
21To burn any blend well you need the right wick for the job
Good wick quality is essential as a main contributing factor to obtain a good, clean burn of any blend.
Factors influencing wick quality– Raw Materials– Chemical Treatment– Braiding Techniques
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Raw Materials Cotton − approx. 42 types world-wide. Main producing countries − China, USA, India, Uzbekistan, Pakistan and Egypt. Decisive for capillary action and stability of the wick are:
– Purity – Cleanliness– Length of fibers
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Raw Materials Oeko-Tex Standard 100
regulates the maximum allowed levels of defined substances which may be present in textiles and dangerous to health. [Example − Pesticides]
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Chemical Treatments One of the most important factors when burn testing
different blends is the selection of the right chemical treatment for the blend in question!
SUXC
NST 2STP
NST 4
100 % Paraffin 100 % Stearic Acid
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Chemical Treatments Choose the wrong treatment and get this:
Stearic acidcandle - butwick treated forparaffin wax(excessive trim)
Paraffin waxcandle - butwick treated forstearic acid (insufficient trim)
Choose the right treatment and get this:Stearic acidcandle + wick treated forStearic acid
Paraffin waxcandle + wick treated forParaffin wax
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Chemical Treatments Sometimes adding colors and fragrance to a paraffin
wax blend can make it react with the candle material in the same way as stearic acid does. Better results maythen be achieved with treatments for stearic acid.
+ + = = STP NST2
= X C SU
S o m e t i m e s
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Wick Braiding TechniquesFlat wicks = 3 bundles with an equalnumber of threads e.g. FW 3x10 =3 bundles, 10 threads per bundle.
Flat wicks with extra stability threadse. g. LX, HZL, TL
Round wicksAt least 8 bundles with an equal number of threads e. g. RRD+ Core bundle (Material variations
possible)+ Tension threads
28Suitability of different wick types (braids) for different materials
Basic rule
For candles with a diameter < 25 mm – Flatwicks
For containers, pillars, votives, tealights etc.– Flatwicks with stability threads or– Round wicks
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Suitability of different wick types (braids) for different materials
Flatwicks are not normally suitable for paraffin wax pillar candles...
...but are often suitablefor stearic acid pillarCandles (with the rightchemical treatment).
Paraffin Wax Pillarwith LX wick =stability threads
FW 3x10 SU
FW 3x16 STP
LX-16
FW 3x14 STP
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Why Flatwicks stand up better in Stearic Acid than Paraffin Wax candles
20 °C 60 °C40 °C 50 °C30 °C
Solid
Liquid
Paraffin Wax Stearic Acid
At 40 °C the short-chain hydrocarbons in the paraffin wax have already started to melt
How different blends melt
Stearic Acidstarts to melt at approx. 52 °C
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The critical “relighting” phaseStearic Acid Paraffin
No glow point at wick tip.
Wick does not trim immediately
Glow point appears at wick tip.
Wick trims
Glow point appears immediately at wick tip.
Wick trims
Glow point disappears as wick becomes saturated.
(Once saturation phase has passed, wick continues to burn with glow point)
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Factors influencing wick selection To start selecting a wick for testing you need to know
– Type of candle material (i. e. blend)– Color / fragrance– Diameter of candle– Method of candle manufacture– Free standing or in container
33Before burn testing, wick tension and stance must be correct
Poured
Pressed
Soot testing
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Soot Testing Device (Quantitative) Emission and Absorbtion Detection Method
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Soot Testing Device (Quantative)
Soot IndexEv (Glass after Burn Cycle)
100 x 1-Ev (Cleaned Glass)
Example1390
100 x 1- = 0.71400
37Factors which influence burning behavior
Use of high quality rawmaterials
Optimal constellationfuel - wick
Consideration of burning conditions(if necessary care of flame)
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Conclusion Paraffin and wick manufacturers supply good
products.
The candle manufacturer must play his part to ensure that a good quality, clean burning candle leaves his factory.
A candle is a system and can only function well as a system. Good ingredients alone do not guarantee a good candle.
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Contact
Sasol Wax C.A. Av. Francisco de Miranda Torre Pequiven, Piso 13 Chacao, CaracasVENEZUELA
Tel: (+58) 212 201 3102 (+58) 212 201 3103
Fax: (+58) 212 201 3199e-Mail: [email protected]
Westdeutsche Dochtfabrik GmbH & Co. KGP.O. Box 25 46D-41312 NettetalGERMANY
Tel.: (+49) 2157 1206 0 Fax: (+49) 2157 6362e-Mail: [email protected]