I learnt something new the other day - how to clean out old candle jars. Despite my best efforts to burn my candles properly sometimes they end up with a hollow through the middle and wax stuck around the sides of the jar after several uses. I love burning scented candles and think it's quite a waste but there's not much you can do about it. So might as well be able to re-use the jar. After the wick has burnt out of an old candle, simply pour boiling water over the wax and watch it melt away and rise to the surface. Once the water has completely cooled there will be a sheet of wax on the top of the water which you can easily lift out.