Your beeswax candle likely sank due to the natural shrinkage of the wax as it cooled and solidified, especially when different parts of the candle cooled at varying rates. This phenomenon often results in depressions or "sinkholes" on the candle's surface.
Understanding Wax Shrinkage and Sinkholes
When candle wax is heated, it expands. Conversely, as wax cools down, it shrinks. This natural property of wax is the primary reason for sinking. The issue becomes prominent during the candle's setting process, particularly when the wax at the edge of the container and around the wick cools and solidifies faster than the bulk of the wax in the center.
Here's a breakdown of the process:
- Rapid Outer Cooling: The wax touching the cooler container walls and surrounding the wick solidifies first, forming a rigid outer shell and a solid layer around the wick.
- Inner Wax Shrinkage: The wax in the center, which remains liquid longer, then begins to cool and shrink.
- Void Formation: As the inner wax contracts, it pulls away from the already solidified outer layers, creating a hollow space, a depression, or a sinkhole beneath the surface, or causing the entire surface to dip. Beeswax, being a harder wax, can exhibit significant shrinkage compared to softer waxes.
Common Causes of Beeswax Candle Sinking
Several factors can contribute to your beeswax candle sinking:
- Pouring Temperature: Pouring wax that is too hot can lead to more significant shrinkage as it cools over a longer period.
- Rapid Cooling: Placing candles in a cold environment, near a draft, or using cold jars can accelerate the cooling of the outer wax, exacerbating the problem.
- Wax Type: Beeswax naturally has a higher melt point and can have more pronounced shrinkage compared to other waxes.
- Container Size: Larger diameter candles have more liquid wax in the center, increasing the potential for shrinkage and sinkholes.
- Wick Size: An improperly sized wick can also affect how the wax cools and melts, contributing to uneven burning or sinking over time.
Preventing Sinkholes in Beeswax Candles
To achieve a smooth, even candle surface, consider these practical tips during the candle-making process:
- Optimal Pouring Temperature: Research and adhere to the recommended pouring temperature for beeswax. This is typically lower than its maximum melt temperature, allowing for more even cooling. You can find general guidelines from candle supply companies like CandleScience or Lone Star Candle Supply.
- Slow and Even Cooling:
- Room Temperature: Allow candles to cool slowly at a consistent room temperature, away from drafts, open windows, or air conditioning vents.
- Insulation: Place cooling candles on a protected surface, like a thick towel or cardboard, to insulate them from a cold countertop.
- Covering: Lightly cover the candles with a box or towel after pouring to help trap heat and slow down the cooling process.
- Multiple Pours: For larger candles, you might consider pouring the wax in two stages:
- Pour the majority of the wax, allowing it to cool and form a slight depression.
- Reheat a small amount of the same wax and pour a second, thin layer to fill the sinkhole once the first layer has almost fully set but is still warm.
- Heat Gun/Hair Dryer: After the candle has fully cooled, if a small depression still appears, you can use a heat gun or hair dryer on a low setting to gently melt the top layer of wax, allowing it to level out. Be careful not to overheat the wax or damage the wick.
By understanding the science behind wax shrinkage and implementing careful pouring and cooling techniques, you can significantly reduce the occurrence of sinking in your beeswax candles.
