Intuitively you may think that burning a candle for a longer time will mean it burns out faster, however in reality permitting a jar candle to burn across its full surface before snuffing it enables it to last longer.
Letting your jar candle burn longer helps to prevent tunnelling. Tunnelling occurs when the candle melts down the middle leaving a “wall” of unmelted wax all the way around the candle container. If your candle begins to tunnel, use a hairdryer to melt the wax until it has melted across the jar.
The second important step is to trim your wick to 6mm just over half a cm. Once you do this your candle will be ready for lighting again. By keeping the wick trimmed, your candle will last longer and burn cleaner! Every time you re-light your candle, trim the black mushroom off that forms on the tip of the wick. This will prevent the black particles from falling into your candle. A wick trimmer is specially designed with a tray that catches the wick particles and cuts the wick evenly. Be careful in trimming the wick evenly for the best burn.
Finally where possible avoid blowing out a candle and use a snuff instead. This extinguishes the candle without creating any soot or smoke. It also helps prevent any wax spill out of the jar.