What to Do When Your Candle’s Glass Turns Black on Top

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You’ve been burning a candle and loving the new fragrance when you notice a thin, grey film forming on the top of the container. The buildup gets worse with every burn, until you have a black ring around the top of the candle. While unsightly, this black deposit has a perfectly normal explanation, and it’s very easy to both prevent and clean. Read on to discover what causes candle glass to turn black, as well as how to prevent it from happening and how to clean off the buildup.

handheld lamps

What causes candle glass to turn black?

Candle glass turns black due to the accumulation of soot. Any type of candle can create soot, though it’s more common with certain types of waxes, such as paraffin wax. Soot is created as a result of an incomplete combustion reaction, and it can be caused by several different factors. One of the main reasons is having a candle flame that is too large, which is, in turn, caused by a longer wick. A longer wick and a larger flame means that more wax will be melted, which gives the candles more fuel. This increased fuel can result in incomplete combustion, which leads to soot.

An uneven burn can also create soot. Long candle wicks tend to curl over or form a mushroom at the top, which creates a lumpy flame that burns some parts of the candle wax more than others. The candle wick may also move off center when the wax is melted, which will also result in an uneven burn and create soot. Finally, placing the candle near a draft or vent can cause the flame to move around, yet again resulting in an uneven burn and causing still more soot.

one candle flame

How can you prevent candle glass from turning black?

Thankfully, soot formation is not inevitable, and there are several steps that you can take to stop soot from forming before it even starts. The first is trimming your candle wick down to one-eighth to one-fourth inch before each burn (make sure the candle has completely cooled before doing this). You can do this with scissors to start, though you might want to get a dedicated wick trimmer so you can continue to do it as the candle burns down. Trimming the wick keeps the flame small and  ensures that it is evenly shaped, helping to prevent incomplete combustion.

If the wick moves during burning, you should also recenter it while the wax is still soft. You can use the wick trimmers or another tool to nudge it back into place. Don’t use your fingers or you might burn yourself. You should also keep the candle away from vents, drafts and other things that might cause the flame to sputter or burn unevenly. Place the candle in a secure location where it won’t be disturbed. A little bit of bobbing is normal for a candle flame, but if it’s really going in and out, or it’s not shaped evenly, try moving the candle to a new location.

Blowing out candle

How can you clean black candle glass?

Despite your best precautions, your soy wax candle may form soot anyway. If your candle glass is turning black, it’s best to clean it periodically to keep the soot from building up. The more soot there is, the harder it will be to clean. Before cleaning the candle, blow out the flame and let the wax and the container cool completely. Dampen a paper towel and rub it over the soot until it dissipates. If the soot is really stubborn, you can use rubbing alcohol instead, which will cut through the buildup. Let the candle dry completely before burning again.

If you have already burned the candle all the way down and are looking to repurpose the jar, you can also use soap and water to remove the candle wax. First, you’ll need to remove the candle wax from the jar (check out the linked guide for instructions on how to do that). Soak the candle container in some soapy water and then wipe with a soft cloth until all the soot comes off. Let the container dry before repurposing.

If all your candles have a black ring of soot, never fear. This unsightly buildup is easy to both prevent and clean up. Follow these tips to keep your candles soot-free and looking good.