Candle Sinkholes Explained: How To Prevent Them In Candle Containers
There is nothing more frustrating than lighting a candle you’ve purchased or carefully made only to notice a large hole forming around the wick. This issue is known as a candle sinkhole, it can make a candle look unfinished. The good news is that they are usually easy to understand, prevent and fix once you know what causes them.
What Is a Candle Sinkhole?
A candle sinkhole is a hole that forms in the wax, usually around the wick when the candle cools and solidifies. Sinkholes are seen during the candle making process, particularly with candles in containers such as metal tins and glass jars. This is because the container can affect how quickly the wax cools around the edges. The outer layer of wax hardens first while the wax below continues to cool and shrink, leaving an empty space beneath the surface.
Sinkholes can vary in size, from small dips that are barely noticeable to deep cavities that affect the candle’s appearance and may require correction before sale. Certain waxes, such as paraffin and soy blends. Understanding why sinkholes happen is the first step towards producing smooth, professional looking candles every time.
What Causes Candle Sinkholes?
Several factors can contribute to candle sinkholes:
Natural Wax Shrinkage
All candle waxes shrink to a degree when they cool. Paraffin is prone to shrinking, while soy and other natural waxes can also develop sinkholes under certain conditions.
Cooling Too Quickly
When candles cool too fast, the surface hardens before the wax underneath has a chance to settle. This increases the chance of air pockets developing within the candle. Cold workspaces can contribute to uneven cooling.
Size of Candle Containers
The size, shape and material of the candle container can influence how the wax cools. Metal tins conduct heat differently to glass, which means they cool the wax more quickly, especially if the tin is cold before pouring.
Pouring Wax at the Wrong Temperature
Wax that is poured either too hot or cold can affect how the candle sets. Hot wax may experience greater shrinkage as it cools, while wax poured too cool may solidify unevenly, creating imperfections in the finished candle.
Air Trapped
Air bubbles can become trapped around the wick when pouring. As the candle cools and the wax settles, these pockets of air may leave a visible hole.
Fragrance Oils
Adding fragrance oils or dyes can change how the wax cools and hardens. These ingredients may affect the wax structure.
How To Fix A Sinkhole
Candle sinkholes are more common than you would think, even the most experienced candle makers deal with sinkholes from time to time. They can be fixed simply by following any of these methods:
Use a Heat Gun: A heat gun can be used to gently melt the layer of wax making it level. Move the heat gun slowly across the candle’s surface. Create small holes around the wick before applying more wax, this will allow trapped air to escape and prevent new sinkholes from forming. A hairdryer on a low setting may also work.
Second Pour: For deeper sinkholes, a second pour is the best option. Once the candle has fully cooled and the sinkhole can be seen, melt a small amount of the same wax and carefully pour over the surface. Using the same wax helps ensure consistency.
Carefully pour a thin layer of melted wax over the surface, without overflowing the container. In most cases it would only be a small top-up required.
Repair holes: If you think there are air pockets underneath the surface, use a wick pin or similar tool to create small holes around the wick. This will help any trapped air to escape and prevent new sinkholes forming after the repair.
Once the repair holes have been created either apply a heat gun or add a small amount of melted wax to fill the gaps. This step is important for larger container candles as the air pockets can cause recurring sinkholes if not treated properly.
Warm metal tins before pouring: To reduce the risk of sinkholes when using metal tins, it can help to gently warm the tins before pouring. They do not need to be hot, just slightly warm to reduce the temperature shock when the melted wax is added. After pouring, allow the candles to cool slowly at room temperature.
How to Prevent Future Sinkholes
Preventing sinkholes starts with controlling how the wax cools and sets. Sinkholes are created by wax shrinking as it cools so the aim is to encourage an even, gradual cooling process and give trapped air a way to escape before the candle fully hardens.
Test Your Combinations
Test your candle making combinations. Waxes, containers and wicks can all change how the candle cools, so it’s really important to do lots of testing. Make small test batches and record your results, that way you will have reliable methods for producing professional looking candles.
Cool candles slowly
When the candle cools down too quickly sinkholes tend to appear. Avoid placing freshly poured candles near open windows, draughts or cold worktops. A consistent room temperature helps the candle cool gradually. The ideal room temperature for making candles is 22°C and 24°C (or 72°F to 75°F) . Avoid moving them too soon as this can disturb the wax structure.
Conclusion
Candle sinkholes are a common part in the candle making process, they are usually easy to understand and fix. While they may be frustrating, they do not always mean that the candle is ruined.
With a little trialing and perfection, candle makers can create more consistent candles that look good when they burn. Whether you’re making candles as a business or as a hobby, understanding sinkholes are a crucial part of improving your quality of candles. When looking for new candle containers, explore Tinware Direct’s range of candle tins available in a variety of sizes and finishes.
