Why Do Candles Get A Layer Of Oil On Top?

Written by Jewel Within


Posted on September 28 2021

Out of all the available candle wax, soy wax provides the best balance between the burn and its fragrance. But on some candles, you might notice that a layer of oil forms at the top as it stays lit. This pooling is called “sweating,” and it affects how well your candle burns, how it looks, and the scent it gives off.

Sweating can happen on the top of a candle for two reasons. One of these can be prevented by burning the candle in the right part of your home; the other is an indication of an improper wax mixture and cheap scent!

What Causes The Layer Of Oil On Candles?

The first reason you might see the fragrance oil pool at the top comes from temperature change around the candle. Soy wax is very sensitive to extreme temperature changes. Moving a candle suddenly from one temperature to another can cause the fragrance to sweat out. As well, it can happen if the candle is in a spot with inconsistent temperature (like by an open window with a cool breeze). The natural oils will separate from the wax and leaving oil on top.

The second way sweating happens is when too much fragrant oil has been added to the wax. The worst effect of too much fragrance is the wax curdling when setting, but this is something a candlemaker can notice. A more subtle side effect is that a thin layer of oil forms on the top of the candle. If the candlemaker doesn’t mix the oil and wax well enough, adds the fragrance at too low a temperature in the process, or chooses one that isn’t suited for the candlewax, the oil won’t bind to the wax surrounding it.

Sweating isn’t just a nuisance – it can make the candle look ugly. When the fragrance bleeds out, it can create small “pockets” between the glass container and the wax. Sweating also changes the look of the surface, creating unwanted crystallization or mottling as the melted fragrance migrates to the candle’s exterior.

How To Avoid Sweating

You don’t have to worry about sweating caused by temperature change. The oil layer that forms at the top doesn’t affect the quality of the candle, the way it burns, or the effectiveness of the scent. You can just wipe the excess oil off with paper towels or tissue after the wax has cooled. To avoid it, keep the candle away from drafts and open windows, direct sunlight, and rooms that have a wide temperature variance.