We purposely created a “problem” candle to demonstrate a sinkhole. In this example, the wick is not centered, the wax was poured at too hot of a temperature, and too high in the jar. We also purposely used a pillar wax (instead of a container wax that we should have used). Result: Massive tunneling sinkhole! YUCK!
What Causes Sinkholes in Candles?
Regardless of whether you are making container, pillar, or votive candles, sometimes sinkholes will occur regardless of how cautious and meticulous you are when crafting your candles.
Sinkholes are the arch nemesis of any candle. You pour your heart and soul into your perfectly executed craft only to find after your long awaited set up time has elapsed that you have a dreaded sinkhole. Ohhh the hatred.
Sinkholes are the crater like openings around your wick. They vary in size and depth, and have a direct effect on how your candle wick functions. Sinkholes occur naturally from the process of the wax setting up. As wax is heated to melt it into liquid form, the wax expands literally taking up more space as it changes form from solid to liquid. On the flip side then, as wax is cooling, hardening back to it’s original solid state; it begins to retract and in essence shrink. If the wax cools too quickly though, the liquid will begin to harden where it sits without filling in the open areas from retracting. This is the reasoning as to why sink holes can appear in your candles. However, this is only one factor to consider. Although sinkholes are easily fixed with re pours, there are a few precautions and tips that we have found to help minimize sinkholes in candles.
The key to remember: Temperature is Everything
The best working environment for setting up your candle making station is somewhere with ventilation as well as a controlled 70 degree temperature, without any drafts or breezes.
In order to achieve the best candle possible temperature must be monitored. We know the effects of pouring a candle below the suggested degree, adding a fragrance at an incorrect temperature, and even melting/pouring wax too hot. Containers and molds are just as finicky when it comes to sinkholes in candles. In order to truly allow your candle to set up naturally, there must be no variances in temperature. Any containers or molds that touch the melted wax must be at room temperature. Natures Garden suggests two options in prepping your molds and containers. If applicable, place your container/mold in a room temperature setting with enough time prior to their use to allow them to naturally come to that degree. This is especially true for those of you that keep your glassware in the basement or garage in the winter months. Your second option is to place your containers/molds on a cookie sheet, and then in the oven on the lowest setting for 15-20 minutes. This is the quick way to warm your containers/molds.
When pouring your melted wax into your room temperature container/mold, it is just as important that your candle has a chance to cool in a uniform matter. What this means is that the outside portion of the container/mold should cool in its own natural time. Shocking the wax to harden by means of refrigeration or a fan will allow for the candles exterior to harden too quickly before the inside area of the candle wax has a chance to naturally release trapped air. This trapped air is another factor that causes sinkholes in candles or small pin sized bubbles in your finished votives.
Because temperature plays such a crucial role in candlemaking, anytime you need to do a second pour the magical time is 2 hrs. Doing a second pour too early or too late on a cooling candle can have big flaws on the physical look of your completed candle. In some cases, it may even result in second sinkhole.
Other Ways to Reduce Chances of Sinkholes
One Natures Garden tip to preventing sinkholes in candles is to stop the pour right where the sides of your container start to change shape. Never expect to pour a candle up the neck of your jar and not get a sinkhole.
Make sure in all of your candlemaking excitement that you do not rush the pour of the candle. Remember, it is not a race to see how fast you can fill your containers/molds. Filling your glassware/molds too fast will cause sinkholes in candles.
What Are the Odds:
Although sinkholes can occur in any candle style, typically single pour pillar and container waxes are less likely to get them as long as you are using the correct wax for your candle style. All waxes are not created equal; using the wrong wax for your intended candle will produce a sinkhole.
It is the nature of the beast that votive waxes will always require a second pour. The key to remember when making votive candles is to only leave 1/16″ open from the top of your votive mold for the second pour. What this does is allows the votive to harden and shrink with just the right amount of open surface area to allow for the second pour to cool in a uniform manner, both preventing sinkholes from occurring again, as well as not showing the second pour line on the finished votive. Also, only leaving 1/16″open in your votive mold for the re pour will prohibit the small air bubbles from occurring on the outside area of your votive candle.
In the instance where a container or pillar candle needs a re pour, it is a wise to poke relief holes half way down the candle before completing the second pour. This gives the cooling wax a final chance to release any air bubbles that may be trapped in the hardening wax before they too become a sinkhole.
On a final note, sinkholes are never fun (that is unless you do it on purpose for a fun test your candle knowledge segment on Facebook). Now that you have an arsenal of sinkhole preventative measures to use, sinkholes may never be a problem for your candles again.