What can go wrong when making candles

Candle Troubleshooting Guide – Common Issues & How to Fix Them

Even experienced candle makers run into problems from time to time. This guide outlines common candle-making issues, their likely causes, and how you can prevent or correct them. With a little troubleshooting, you'll be back to making beautiful, consistent, and safe candles in no time.

1. Wick Problems

Symptom: Excessive smoke, mushrooming, tunnelling, drowning wick Causes: Wrong wick size or type, high fragrance load, incorrect burn time Solutions:

• Choose wick based on wax type, fragrance load, and vessel size
• Test different wick series (e.g. CDN vs. HTP) for better results
• Trim wicks to 5mm before each burn
• Test burn each batch for at least 3–4 hours

2. Wet Spots

Symptom: Patches where wax pulls away from the glass Causes: Shrinkage during cooling, glass not pre-warmed Solutions:

• Pre-warm glass containers slightly before pouring
• Pour wax at a lower temperature for gentler cooling
• Allow candles to cool in a draft-free area on a flat surface

3. Frosting (Soy Wax)

Symptom: White, chalky film on surface or sides of candle Causes: Natural soy crystal formation Solutions:

• Use smooth, even cooling conditions
• Add a small percentage of paraffin or soy stabiliser (if suitable)
• Accept it as part of soy wax's natural character

4. Sinkholes

Symptom: Sunken or hollow areas inside or under the surface Causes: Air pockets from wax contraction Solutions:

• Poke relief holes after first pour and top off with a second pour
• Pour wax slowly and steadily to reduce trapped air
• Keep wax temperature consistent to slow cooling rate

5. Rough or Bumpy Surface

Symptom: Uneven or cratered tops after setting Causes: Natural wax crystallisation, cooling too fast Solutions:

• Use a heat gun to lightly smooth the top layer
• Pour at optimal wax temperature (not too hot)
• Cool in a room free from drafts and sudden temperature shifts

6. Poor Scent Throw

Symptom: Weak fragrance when cold or burning Causes: Low fragrance load, incorrect temperature, incompatible fragrance Solutions:

• Add fragrance at the right wax temperature (usually 60–70°C)
• Use waxes designed for fragrance retention
• Increase fragrance load gradually, within safe IFRA limits
• Allow proper curing time (especially for soy — 1 to 2 weeks)

7. Discolouration

Symptom: Yellowing or colour fading over time Causes: Fragrance oil oxidation (e.g. vanilla), UV exposure, incompatible dyes Solutions:

• Use UV inhibitors or store candles away from light
• Avoid vanilla-based fragrances if discolouration is an issue
• Test dye compatibility with each fragrance batch

8. Excessive Smoking or Soot

Symptom: Black smoke, residue on jars Causes: Oversized wick, poor wax blend, overloading fragrance Solutions:

• Use a smaller or more suitable wick type
• Keep wick trimmed between burns
• Reduce fragrance load if beyond safe limits

9. Tunnelling

Symptom: Candle burns down the centre, leaving wax on sides Causes: Wick too small, not burning long enough in early stages Solutions:

• Use a larger wick or test a different wick series
• Ensure the first burn lasts long enough to reach full melt pool
• Encourage customers to allow an even burn on first use

10. Glass Breakage

Symptom: Jar cracks during or after burning Causes: Inappropriate container, temperature shock, poor wick placement Solutions:

• Use only heat-resistant, purpose-made candle glassware
• Pre-warm containers before pouring
• Keep wicks centred and away from glass walls

Every candle maker faces challenges, but understanding the root causes allows you to refine your process and create consistent, high-quality candles. Testing is essential — not just once, but every time something in your formula or container changes. With care, documentation, and a bit of patience, these issues can be turned into valuable lessons that strengthen your craft.