Don’t burn a new candle for only a few minutes.
The first time you burn a container candle, you should allow it to form a complete pool of melted wax across the surface of its container, from rim to rim. This is because wax has a memory, and on subsequent lightings, the wax pool will struggle to go beyond the circumference of the previous burn. The candle will most likely tunnel down into the wax from then on. The wick will sink deeper and deeper into the candle, and the wax on the sides will never burn, shortening the life of your candle.
Keep wicks trimmed. A trimmed wick will give you a nice bright flame. A long or a crooked wick can result in uneven burning, which can lead to bursts of high flames or smoking. Wicks should be about one-fourth-inch high for best burning; don’t trim them lower than that. Slatkin’s method is to wait for the candle to cool 100 percent and turn it upside down. Take off the charred part with a tissue, and your wick will be good to light.
Avoid putting burning candles in the path of vents, fans or drafts. Currents of air can cause candles to burn unevenly or produce excessive smoke or soot that can leave messy black stains on your container. If a wick becomes too long or an air current disturbs the flame’s teardrop shape, small amounts of unburned carbon particles can escape.
Keep the wax pool clear of any debris. Don’t mess up the candle pool with pieces of cut-off or charred wicks or used matches. Introducing debris into the wax will interfere with the chemistry of the candle and may cause it to burn unevenly. This could clog the wick and prevent it from drawing up the fragrance oil and diffusing the scent.
Let a candle completely cool before lighting again. A candle in a container takes about two hours to completely cool down, but it’s worth the wait both for safety and function. It’s much safer to trim the wick when the wax pool has hardened. A hot pool of melted wax can burn your fingers if you dive in for a wick before it’s cooled and solidified.