No matter what type of candle you’re making or how meticulous you are, candle wax can sink in the middle, creating a sinkhole. Not to be confused with tunneling (which occurs during the first burn of a candle), sinkholes look like a crater around the candle wick and vary in depth and size.
So, why do candles sink in the middle? When making homemade candles, you melt the wax and pour it into the jar with the wick, then wait for it to harden. During this process, the hot wax expands and then starts to cool and contract.
The sides cool quickest, and because the wax needs something to stick to, it will stick to the sides first. When this happens, the wax starts to sink in the middle. The wax may also stick to the wick. However, it usually starts to sink as it continues to cool down.
How to Fix a Sinkhole in a Candle
It’s possible to fix sinkholes in your candle, starting with proper preparation.
Prepare your Containers Correctly:
Using jars and molds that are too cold causes the wax on the outside of the candle to harden too quickly, resulting in a sinkhole in the candle. To avoid this, try the following:
- Store jars and molds at room temperature before beginning the melting and pouring process.
- If you forget this step or your containers are too cold, place them on a cookie sheet and gently warm them in the oven at the lowest setting for between 15 to 20 minutes.
Pour the Wax at a Lower Temperature:
Another way to prevent sinkholes is to pour your candle wax at a lower temperature. However, there’s a knack for this method and it’s not recommended for beginners. If you pour your wax at a temperature that’s too cool, your batch may not solidify correctly.
Use a Heat Gun to Fix Candle Sinkholes
Try investing in a heat gun. Use the heat gun to warm the surface of the candle and fill any cavities in the candle.
A couple of hours after pouring, when the wax is cooled and beginning to set, poke holes in the top of the wax using a chopstick, bamboo stick, or skewer. Carefully poke the wax around the middle of the candle as it cools to look for air pockets or cavities. If you find one, gently heat the wax, allowing the liquid wax to fill any holes. You can also use the heat gun to even up the surface of your candle.Â
If you can’t get your hands on a heat gun, get creative with a hairdryer to heat the wax on the surface of the candle and fill any holes, or pop your candle in the oven on low heat and slowly melt the wax, checking regularly. Use a stick to remove air pockets and ensure all holes are completely filled with wax.
Do a Second Pour
A second pour is another way to fill up a sinkhole in your candle. Simply set aside some wax when pouring your candles so you have enough for two pours.
With this method, you shouldn’t do the second pour too soon after the first one. This could ruin the look of your candle or create another sinkhole. Make sure the candle has completely hardened and cooled down before the second pour, using a chopstick to open the holes and fill them entirely.
A trick to ensure the wax cools down evenly without sticking to the sides is to gently heat the glass before pouring. While heating the glass too much will stop the wax from solidifying, gently warming it in the oven for a few minutes should be just enough to ensure the wax cools evenly.
How to Get a Smooth Top on Soy Candles
If your soy candle looks a bit lumpy on top, this is most likely due to the pouring temperature. For smooth tops on your soy candles, you will need to invest in a good thermometer.
Many people aren’t aware of how crucial temperature is when it comes to making candles. Changes in the weather and humidity levels can affect how the wax dries and result in sinkholes or lumpy surfaces on your candles.Â
To get a smooth top on soy candles, try gradually increasing the pouring temperature until the result is smooth. The recommended pour temperature serves as a guideline, but you may need to experiment to find the perfect result.
Certain essential oils and fragrances, such as vanilla and lavender, can cause the top of soy candles to curdle and go lumpy. This can be solved by reducing the amount of essential oil or fragrance you add or by adjusting the pour temperature slightly.
How to Stop a Beeswax Candle Sinkhole
While not 100% fool-proof, there are some ways to stop sinkholes forming on beeswax candles. Try the following:
- Start by poking relief holes around the wick using a bamboo stick, chopstick, or skewer to find holes or air pockets (the depth of the relief holes should be about an inch less than the candle).
- Use a heat gun or hair dryer to gently heat the candle.Â
- As the candle heats up and the wax melts, it will begin to trickle down into the relief hole.  Â
- Once the hole is filled, gently heat the candle again to remove any divots and get a completely smooth surface on your candle.
