Homemade candles sink in the middle primarily due to the wax cooling too quickly, making it difficult for the wax to adhere uniformly to the wick. Pouring at a more optimal temperature or a second pour may solve this problem.
Understanding Sinkholes in Candle Making
Sinkholes can occur in various forms—small surface craters, larger internal pockets, or uneven cooling points across the wax. Addressing the type of wax and the pouring method significantly minimizes these issues.
Key Factors Contributing to Candle Sinkholes
1. Wax Density and Cooling Time
Dense waxes are prone to cooling slowly and developing air pockets that lead to sinkholes. Testing the optimal pour and cooling temperatures for your specific wax type can be essential to avoid this.
2. Fragrance Oils and Additives
Certain fragrance oils, particularly thicker or incompatible ones, can alter wax density, making it harder for the wax to cool evenly. Opt for compatible fragrance oils to prevent sinking issues.
3. Wick Placement and Sizing
Improper wick sizing for large candle molds or misaligned wicks may cause uneven wax distribution, leading to sinking or even tunneling. Ensure wicks are centered and of appropriate thickness to match the candle diameter for a balanced cooling process.
4. Environmental Factors, Like Altitude and Air Pressure
Environmental elements, including altitude, air pressure, and even humidity, can also lead to sinking. High-altitude areas often experience quicker cooling rates, which may increase the likelihood of sinkholes.
5. Wax Blends and Additives
Certain wax blends, such as paraffin-soy mixtures, have specific cooling and setting requirements that help reduce the risk of sinkholes. Additives like stearic acid may also be beneficial to improve texture and durability, leading to a more stable cooling process.
Container Shape and Dye Effects
Container shapes, particularly narrow or deep vessels, can lead to uneven cooling, promoting sinkholes. Additionally, thick candle dyes can interfere with cooling, causing irregular solidification. Choosing the right container shape and dye consistency are preventive measures.
Practical Tips to Prevent Sinkholes in Candles
Here are steps to improve candle structure and avoid dips:
Preparation
Ensure molds and containers are at room temperature. Pre-warm them by placing them in the oven on low heat for 15-20 minutes if needed. Containers too cold during pouring lead to uneven cooling, trapping air within.
Pouring Temperature
A slower pour at a moderate temperature helps prevent air bubbles and allows wax to adhere better. Avoid pouring too hot, as it may cause rapid cooling and sinking. Testing the temperature on small batches can help you find the ideal range.
Correct Wick Positioning
Using wick stabilizers and double-checking wick alignment during the pour reduces uneven wax cooling and improves burn performance.
Cooling Time
Extending cooling times, especially for larger candles, helps achieve an even surface. Avoid placing candles in refrigerators or cool environments directly after pouring, as quick temperature drops create a hardened outer shell with a soft interior.
Fixing Candle Sinkholes
If sinkholes form, here are reliable methods to repair them:
Heat Gun Method
Using a heat gun, gently melt the candle’s surface. Insert a stick to release trapped air, and let the melted wax settle evenly. This approach is fast and ensures an even surface finish.
Second Pour Method
After initial hardening, a second pour at a slightly lower temperature fills in gaps, improving candle stability. Allow enough cooling time after the first pour (typically about two hours) to ensure no new sinkholes form.
Alternative: Hairdryer or Oven Method
If a heat gun isn’t available, a hairdryer on low heat or an oven set to low can work similarly. Always monitor closely to avoid melting more than intended.
Recognizing and Fixing Sinkholes in Specific Wax Types
Different wax types behave differently during the cooling process. For instance, votive waxes are more prone to sinkholes and often require a second pour to smooth out air pockets.