I approach candles with a set of rules I try my best to adhere to:
Trim the wick to 1/4” before burning, and between burnings
Never burn the candle for less than an hour, about the time it takes to melt the wax evenly across the top for a smaller candle
Gently snuff the candle’s flame when done burning to prevent a waxy mess
Despite these recommendations, sometimes it’s just not possible (or safe) to leave a candle burning as long as it needs to burn evenly, or the wick was initially off-center in the candle, or the quality of the wax does not allow for an even burn, or there was a draft in the room…
In order to remedy a candle that’s still full of wax, but just won’t burn anymore, I got a set of new wicks from Amazon (thanks, Christina!) and a candle warmer. Melt the candle until the wax is completely melted, and insert a new wick. Melting the candle fully may take several hours, but as it melts, you still get to enjoy the aroma of the candle! Tape the wick to a pencil set across the top of the candle to keep it in place, and once the wax has set, trim the wick to 1/4” and you’re ready to burn.
Life Hack: Use the candle warmer to keep your coffee warm in the morning as you get ready and you’ll never suffer cold coffee again!