So there is this on going debate about soot from candles. The big issue is claims from soy candle manufacturers that soy candles don’t produce any soot or they are soot free. We have been making paraffin candles a long time and soy candles since August 2008. While we have never believed that soy candles do not produce any soot we get asked about it quite often. People want to know if the air quality in their homes will be better burning a soy candle over a paraffin. According to the National Candle Association in an answer to the question “Is candle soot harmful?” they replied:
“No. The minuscule amount of soot produced by a candle is the natural byproduct of incomplete combustion. Candle soot is composed primarily of elemental carbon particles, and is similar to the soot given off by kitchen toasters and cooking oils. These everyday household sources of soot are not considered a health concern, and are chemically different from the soot formed by the burning of diesel fuel, coal, gasoline, etc.”
In response to all the questions, I did my own test. I made two 16oz jar candles with the same fragrance and wicks, and burned them both daily for about 8 hours here at work until they were gone. I maintained both candles by trimming the wicks when they became a little to long from such a long burn period. The idea was to have the only difference be the wax type, 1 was soy, 1 was paraffin and see the amount of soot produced under a normal burn. I took this picture with the worst soot side facing the camera. The soy candle on the left has less soot around the top of the jar than the paraffin candle, but both have soot. Some of the soot around the tops of the jars was a result of blowing the candles out and the smoke that follows. The environment that these two candles were burned in was our factory and therefor quite drafty. Had these been burned in a home there would have been less soot on each jar. A second thing to keep in mind is that container candles have the hardest time burning with a still flame. They fight between hot air going out and cooler air coming in causes the flame to dance, causing more soot.
So what is the short answer to the soot question? Soy candles are not soot free but will produce less soot when burned under the same conditions as a paraffin candle.
U.S. Candle Company Blog 
Great Blog! Very Informative.
Hey John, Im having trouble with wooden wicks creating a lot of soot. I have read through your article and wondering if using such a large jar and wide wick could be hard to manage. My jar is 10cm diameter and the wooden wick is a double wick about 1.7cm wide. So because ether flame is so big due the big jar it is alway dancing as its so wide. I thought it was when I first light it as the flame goes above the jar but it seem st still smoke (but less) as it lowers in the jar. I have a video of it Id love to show you?
Hi Fiona,
I have to admit I don’t have a lot of experience with wood wicks. I have messed around with them a little bit doing some testing but we don’t use them on a regular basis. Is it possible to cut the wick down a little bit before first lighting it? Once the candle has been lit for a while, does it melt out to the edge easily?