Making candles is both a science and an art. Even after choosing the right wax, fragrance, wick, and container, you may still encounter problems like frosting, sinkholes, tunneling, wet spots, or uneven candle tops.

The good news is that most candle imperfections have a clear cause and can be fixed with small adjustments to your candle-making process.

In this guide, I’ll cover the most common candle wax problems, why they happen, and how to prevent them.

1. Frosting

Frosting appears as white, cloudy patches or crystal-like marks on the surface and sides of candles. It is especially common with natural waxes like soy wax. While frosting does not affect the candle’s performance, it can make candles look uneven or less polished.

Causes of candle frosting:

• Natural crystallization of soy wax
• Rapid temperature changes while cooling
• Cooling candles too quickly

How to prevent frosting:

1. Pour candles at a consistent temperature recommended for your wax
2. Allow candles to cool slowly at room temperature (do not put them in the fridge)
3. Avoid placing candles near windows when outdoor temperatures differ significantly from indoor temperatures
4. Mix fragrance oil slowly and thoroughly
5. Avoid overheating and repeatedly reheating wax

How to fix frosting?

Frosting cannot usually be completely removed, but you can improve the appearance by using a heat gun to melt the surface layer, improving your cooling process for future batches or if your type of wax is especially prone to frosting and nothing else works, use containers with a less visible surface.

2. Tunneling

Tunneling happens when a candle burns down the middle, leaving a thick ring/tunnel of unmelted wax around the edges.

A properly burning candle should create a melt pool that reaches close to the container edges.

Causes of tunneling:

• Wick is too small for the container
• Wick is too short
• The candle diameter is too wide for one wick, and you need two or more wicks

How to prevent tunneling:

1. Choose the correct wick size for your container diameter (check your manufacturer’s recommendations when buying wicks)
2. Perform a full melt pool test before selling candles
3. During the first burn, allow the candle to burn until the melt pool reaches the edges
4. Use multiple wicks for larger containers

Can you fix tunneling?

You can try removing the excess wax around the wick but the best option would be to just take all wax out, remove the wick, clean your jar and make the candle again using a larger wick size.

3. Sinkholes/Pitting

Sinkholes are holes or cavities that form inside candles as wax cools. They often appear near the wick or underneath the surface and form rough areas on the top of the candle. This issue is more common with paraffin and palm wax.

Causes of sinkholes:

• Wax cooling too quickly
• Pouring wax too hot
• Air trapped during pouring
• Wax shrinking as it cools

How to prevent sinkholes:

1. Pour wax slowly to reduce air bubbles
2. Tap the container gently after pouring to get air bubbles out
3. Use a second pour to fill any gaps and achieve a smooth top (do this with palm wax)
4. Avoid moving candles around while cooling
5. Follow your wax manufacturer’s recommended pouring temperature

How to fix sinkholes?

Apply a second layer of wax on top of your candle or use a heat gun to smooth out the surface. Pour your next batch at lower temperatures.

4. Uneven Candle Tops

After cooling, candles may develop rough, cracked, bumpy, or uneven surfaces. This is one of the most common issues among handmade candle makers.

Causes of uneven tops:

• Wax cooling too quickly
• Temperature fluctuations
• Pouring wax at the wrong temperature
• Fragrance oil percentage too high
• Moving candles before they fully set

How to prevent uneven candle tops:

1. Cool candles slowly in a stable environment
2. Keep room temperature consistent
3. Do not put candles in the refrigerator or freezer

How to fix uneven candle tops?

Thankfully, this is one of the easiest issues to fix. Just use a heat gun to smooth out the top layer or add a thin finishing layer of wax.

5. Wet Spots (Jar Adhesion Problems)

“Wet spots” are not actually wet, but they look like dark patches between the wax and the glass jar where the wax has pulled away from the glass. Wet spots are very common with container candles, especially with soy wax candles. They are a cosmetic issue and do not affect candle performance; in fact, you are likely to find candles in stores with jar adhesion problems. Customers are usually not bothered by this, and they rarely even notice it.

Causes of wet spots:

• Wax shrinking away from the container
• Temperature differences between wax and glass
• Pouring wax too hot or too cold
• Containers not being warmed before pouring (most common)

How to prevent jar adhesion issues:

1. Warm containers before pouring wax
2. Store finished candles at a stable temperature
3. Pour at the correct temperature for your wax
4. Avoid sudden temperature changes during cooling process

How to fix wet spots?

You can try reheating the area or covering the spot with your candle label.

6. Air Bubbles

Small bubbles can appear inside or on the surface of candles, creating an uneven appearance. They occur when air gets trapped inside the wax. The bubbles on the top of the candle can be easily smoothed out with a heat gun. However, trapped bubbles in pillar candles that remain at the bottom of the mold will not be visible until you demold your candle and see empty spots where the bubbles were. These cannot be fixed, but they can be prevented.

Causes of air bubbles in candles:

• Stirring and pouring wax too quickly and aggressively
• Trapped air around decorations or wicks
• Not warming up your containers

How to prevent air bubbles?

• Stir slowly and gently (using a wider/larger spatula is better than stirring with a thin spoon)
• Pour wax carefully down the side of the container
• Warm your containers before pouring wax
• When you are using molds, tap them lightly for air bubbles to escape

7. Cracks in Candle Wax

Cracks usually happen because the wax contracts too quickly while cooling. This is why you should never put your candles in the fridge or freezer. Unfortunately, cracked wax cannot be fixed, and you will need to redo your candle.

Causes of wax cracking:

• Cooling too fast
• Cold room temperature
• Large candle diameter
• Incorrect pouring temperature
• Not warming up your container

How to prevent wax cracking?

• Cool candles slowly at room temperature
• Always heat your containers and molds before pouring
• Keep the workspace temperature stable (do not open windows if it’s colder outside)
• Pour large candles in stages

8. Wax Pulling Away From the Wick

Sometimes wax separates around the wick, creating a hole or gap. For me personally, this is one of the most frustrating issues because it can be so easily prevented.

Causes of wax pulling away from the wick:

• Wick not properly secured
• Wax cooling too quickly
• Poor wick centering

How to prevent wax pulling away from the wick?

• Secure the wick with a wick holder firmly before pouring
• Always use wick stickers or glue
• Pour slowly around the wick
• Avoid moving candles and touching the wick while cooling
• Do not cut the wick before the wax fully hardens

Candle Wax Troubleshooting Guide

Problem	Main Cause	Solution
Frosting	Soy wax crystallization	Cool slowly, reduce temperature changes
Tunneling	Wick too small	Use a larger wick
Sinkholes	Wax shrinking	Do a second pour, tap the container
Uneven tops	Cooling issues	Adjust pouring and cooling temperature, use a heat gun to smooth out the top
Wet spots	Poor jar adhesion	Warm up your jars, stabilize temperature
Bubbles	Air trapped in wax	Stir and pour slowly and carefully
Cracks	Cooling too quickly	Slow down the cooling process, do not put candles in the refrigerator
Wick holes	Air around wick	Secure wick properly with wick tab and wick holder, wait for wax to fully harden before cutting the wick

Summary

Perfect candles rarely happen on the first try. Candle making requires testing because every combination of wax, fragrance oil, wick, container, and environment behaves differently.

To ensure repeatable results, keep notes for every batch, including:

• Wax type and amount
• Fragrance oil percentage
• Pouring temperature
• Wick size
• Room temperature
• Burn test results

Small adjustments can make a huge difference in the final quality of your candles. With proper testing and patience, you can create smooth, professional-looking candles with excellent scent throw and a clean burn every time.