With a candle wick trimmer, you'll extend the life of your candle, providing more light or fragrance for your home. Leaving a wick long means that you’ll have a larger flame, which will melt more wax and give the candle more fuel. This larger amount of fuel can lead to incomplete combustion, which in turn creates more soot, making your candle container black and dirty. (Reducing the soot also makes it easier to repurpose the candle jar when you’re done burning the candle.)
 
Every time you burn a candle for four hours, extinguish the flame and let the candle cool to room temperature. This usually takes about two hours for larger candles. Then, trim the candle wick down to one-eighth to one-fourth inch before relighting again.