Where there's smoke...
Customers often ask us why we don't label our candles as 'smokeless', since they burn without smoking. Our answer is that although a well-made candle indeed shouldn't smoke, whether or not it does depends on the conditions in which it is burned.
As a result of misinformed or misleading marketing, people often incorrectly believe their candles can or cannot smoke (soot) because of the wax type, fragrance, colorants or additives used in the candle’s formulation, but sooting is primarily due to flame and combustion disturbances.
When burnt in proper conditions, a well-made candle shouldn't smoke. However, if you expose a candle, any candle, to a draught, it will start to smoke. Likewise, blowing out a candle will cause it to smoke. This is regardless of the type of candle; it is a result of incomplete combustion.
So assuming you have a well-made candle, be it of beeswax, coconut, palm, paraffin or soy wax, or a mix of these, let's look at how to make it smokeless by addressing the causes of smoke and the ways to remedy them.
Wick : Keep your wick trimmed to 6mm. This goes for all wicks, whether they're cotton, paper-core or wood wicks. A wick that is too long won't be able to draw wax all the way to the top, and the wick itself will start to burn, causing it to smoke. A wick that is too long can also cause a candle flame to grow too long and flare, again producing smoke.
Draught : If a draught disturbs the ideal teardrop shape of the flame, small amounts of unburned carbon particles will escape from the flame as a visible wisp of smoke (soot). Any candle will soot if the flame is disturbed. To avoid this, move your candle out of the draught, or shield it from any draughts.
Jar candle : Jar candles, for instance your standard scented soy candle, often start smoking as the flame goes deeper into the jar. As hot air rises up out of the jar, and cold air gets sucked in to the jar to feed the flame, the air flow gets disrupted, causing the flame to flicker and smoke. You can see the results of a soot-producing candle on the rim of your glass container in the form of a black ring. A candle capper or lid can help by separating the air flows.
Small container : If your candle is inside a container that is too small, the air flow can get disrupted for the same reason as in a jar candle, and smoking can occur. To avoid this, choose a bigger container or smaller candle, to allow more space for the air to flow undisturbed.
Tunnelling : Tunnelling has the same effect on a candle as a container that is too small or a jar; in this case, the unburnt rim of the candle itself acts as a jar and causes smoking. To avoid tunnelling, make sure the initial burn is long enough to melt the candle all the way to the edge, and avoid single-wick pillar candles over 10cm in diameter.
Wax purity : Always choose candles with high-purity wax. Any impurities mixed into the wax, including scent oils, can impair combustion conditions and cause sooting. Try to avoid candles that are soft to the touch, as well as overly scented candles, as these generally have oil mixed into the wax.
Extinguishing : The greatest amount of sooting from a candle generally occurs when the flame is extinguished, interrupting the combustion process. Instead of blowing out your candle and ending up with a smouldering and smoking wick, dip the wick: extinguish your candle by pushing the wick into the pool of hot wax and pulling it back out.
So even though there's no such thing as a smokeless candle, you can burn well-made candles in a smokeless way and enjoy a clean candle experience by following the above tips.
For more advice on how to burn candles, please read here.
- Report on the Ökometric Wax and Emissions Study - Bayreuth Institute of Environmental Research in Germany (Ökometric GmbH), 2007
- Characterization of Fine Particle Emissions from Burning Church Candles - Fine, P, Cass, G, Simoneit BRT, Environmental Science & Technology, Vol. 33, No. 14. 1999
- Fine Particulate Matter Emissions from Candles - Guo Z, Mosely R, McBrian J, and Fortmann R, Proceedings from The Symposium on Engineering Solutions to Indoor Air Quality Problems, Raleigh NC, 2000
- Levels of Selected Organic Compounds in Materials for Candle Production and Human Exposure to Candle Emissions - Lau, C., H. Fiedler, O. Hutzinger, K.H. Schwind, and J. Hosseinpour, Chemosphere 34:1623–1630, 1997