What are sinkholes?
A "sinkhole" refers to bubbles or gaps that are formed inside the candle, below the surface, as the candle cools and sets.
These bubbles create a trap of air under the surface of the candle, which are then revealed during burn time. This can result in an uneven melt pool, as the liquid wax fills the air pockets as the candle burns.
A very sad (but perfect and fixable) sinkhole
How do I avoid sinkholes?
The double-pouring technique is a great trick for various issues - including avoidance of sinkholes. To follow this method, one first fills around 90% of the candle with scented wax. Once this has cooled and developed a slight surface, the second pour fills the candle to the desired level.
Double pouring reduces the risk of sinkholes, as it allows more area for air bubbles to rise, before the candle begins to solidify.
Sinkholes can be avoided by pouring your candles in a temperature-controlled room, and ensuring an even temperature and environment as the candles set.
How can I fix sinkholes?
Unlike some other candlemaking mistakes, sinkholes are very easily fixed.
In the case that you suspect your candles have a sinkhole beneath the surface, we recommend creating a relief hole.
A relief hole can be created by simply puncturing the wax above the sinkhole, after the first pour of the candle.
A relief hole can be created either before the candle has completely set, or once the candle is cured. In the latter case, you'll want to heat the surface so it can re-melt smoothly.
Can I use a heat gun?
Heat guns are a very popular tool in candle-making, as they are a quick fix to uneven surfaces and setting.
However, heat guns work by heating the surface of your wax far above the temperature expected through regular candle use.
As a result, it can "burn" the fragrance contained in that wax, rendering the surface effectively scentless.
At Vuur, we never use heat guns. In addition to making the wax too hot, heat guns can also cause candles to sweat - both of which we aim to avoid with our candles.