When a Candle Is Done
The signs are there. Most people miss them because no one has ever explained what to look for.
Reading the End of a Candle
Every candle has a natural endpoint, and most people walk right past it in both directions — abandoning a candle that had plenty of life left, or grinding away at one that had stopped being useful several burns ago.
The clearest sign you should stop is the wax level itself. When the melt pool starts reaching within roughly half an inch of the vessel's base, the game has changed. That shallow layer of liquid wax heats the glass or tin rapidly from below. The vessel gets hotter than it was designed to handle, any surface it sits on is now at risk, and the wick — with nothing to cool it — burns hotter and less steadily. This is not a theoretical problem; it is the point where a candle that has behaved perfectly for twenty hours can suddenly become a nuisance.
A related signal is wick position. If the wick has shifted, tilted or burned down to the point where it is practically lying against the side of the vessel, the flame will scorch the glass and the remaining wax will burn unevenly. At that point the candle is not really functioning anymore — it is just smouldering in an expensive container.
Scent is another honest indicator. Many candles lose fragrance noticeably in their final third as the fragrance-loaded upper wax has been consumed and the base wax has held less scent through the whole pour. If you're burning a candle primarily for its smell and the throw has dropped off sharply, the candle has largely done what it can.
What about the wax left behind? Almost every container candle ends its life with a disc of solid, unburnable residue at the bottom — wick sustainer visible in the centre. This wax is perfectly usable in a wax melt warmer. Scoop it out, warm it gently, and you'll usually recover some fragrance. It is not waste unless you treat it as waste.
What you should not do is add water, pour in more wax on top, or try to rewick a finished candle — all of these create more problems than they solve.
Stop at the right moment. The last half inch of wax is not a personal failure.