One of the most talked about candle attributes is whether or not they burn clean. For those who rarely burn candles, a cleaner burn may not mean that much, but for those who have had black left around candle jars and the gray, sooty residue left behind on walls, drapes or furnishings, a candle that produces less or no soot is a breakthrough.
The science of petro-carbon soot
Soot is a solid particle that results from incomplete combustion of carbon containing fuels, primarily petroleum-based fuels. This is called petro-carbon soot. Most candles where the type of wax is not noted, or it is marketed as a soy-blend contain paraffin wax. Paraffin wax is a petroleum by-product created when crude oil is refined into gasoline. You may think you are buying a natural soy candle, but it could actually be made with a blend of natural soy wax and paraffin or pure paraffin, both of which produce petro-carbon soot.
Furthermore, there are several carcinogenic compounds (cancer-causing agents) found in paraffin candles. Virtually all of them have been considered "toxic air agents" by various environmental agencies. Since soot particles are very small, they can potentially penetrate the deepest area of the lung.
While burning paraffin and soy blend candles both create petro-carbon soot, 100% soy wax candles produce zero petro-soot. Keep in mind the only completely soot- free candle flame is a natural gas flame. The flame is completely blue and has what is called complete combustion. While soy wax candles have incomplete combustion which produces low soot, it is not the toxic black petro-carbon soot that is found in paraffin-based candles. The other benefit of buying 100% soy wax candles is that soy is a natural sustainable source and has contributed to helping farmers.