Scented soy candles are a wonderful natural alternative to paraffin candles, but there are a few things about natural waxes like soy that cause them to perform quite differently from paraffin candles.
Soy wax is made entirely from soy beans, which are crushed and then processed to extract the wax. Soy wax burns at a cooler temperature than paraffin wax, and relies on a "melt pool" to disseminate fragrance. As the wax melts, the fragrance in the candle is heated and evaporates into the air.
When burning a soy jar candle for the first time, make sure to let the wax melt until the melt pool reaches the sides of the jar. This should take about one hour for every inch of the diameter of the top of the jar - in other words, if the top of the jar is 2 inches across, it will take around two hours for the wax to melt to the sides of the jar.
When you burn your candle again, it will take much less time for the wax to melt to the sides of the jar. This is because soy wax has a "melt memory". Your soy jar candle will always melt outward to the same point that you allowed it to the very first time you burned it.
Sometimes your soy candle wick may have a "mushroom" on top of the wick after you have burned it. This mushroom cap is unburnt fragrance and wax that has been "wicked up" to the top of the wick, and has cooled before being completely burned off.
The mushroom cap will not hurt your candle unless you allow it to become too large. If the mushroom cap is too big then your candle will have a large flame and burn less efficiently. You can dispose of the mushroom cap by very gently crushing it with a tissue. Don't pull or twist.
Then dump the "cap" pieces into the trash.
The best way to avoid having a big mushroom cap is to always keep your wick trimmed to 1/4" between burnings, and not to burn your soy jar candle for more than about 3-5 hours at a time.
Some soy candle manufacturers claim that soy candles do not produce soot. Of course, anything that burns produces some soot. Soy candles do not produce as much soot as paraffin candles, nor do they produce "black soot" like paraffin (the greasy black film on the sides of a paraffin candle jar is "black soot").
Soy candles produce a very small amount of "white soot", which won't discolor your jar or furniture or walls, and doesn't have the same greasy properties which make black soot so difficult to clean up.
Soy jar candles are a terrific natural alternative to paraffin candles, producing much less soot than paraffin and no black soot. Although soy candles represent only about 2% of the total candle market at this time, they are a growing influence in the candle industry. With a few simple steps and proper maintenance, a soy jar candle can be enjoyed and remain fragrant through the life of the candle.