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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: venezuela@sasolwax.comwww.sasolwax.com

Westdeutsche Dochtfabrik GmbH & Co. KGP.O. Box 25 46D-41312 NettetalGERMANY

Tel.: (+49) 2157 1206 0 Fax: (+49) 2157 6362e-Mail: info@wedowick.dewww.wedowick.de