For consistent performance and a safer, more professional product, Wick testing isn’t optional.
Whether you’re launching your first collection or refining an existing range, correct wick selection directly impacts burn quality, scent throw and safety. There is no universal wick that works across every wax, fragrance and vessel combination. Every candle formulation must be tested.
This guide covers exactly what you need to know about wick testing.
Why Wick Testing Matters
A Wick controls how your candles burn. If it’s wrong, everything else suffers
Poor wick selection can lead to:
- Tunnelling
- Excessive mushrooming
- Sooting
- Weak scent throw
- Overheating containers
- Failed safety assessment
For growing brands, inconsistent burn performance can quickly erode customer trust. For new makers, it can result in wasted stock and avoidable reformulation.
Professional candle makers test every new combination of:
- Wax
- Fragrance
- Dye
- Vessel size
Even small adjustments can change how a wick performs.
What affects Wick Performance?
Understanding the variables in Candle Making makes testing more efficient.
Wax Type
Different waxes burn at different rates and viscosities.
- Soy wax typically needs a stronger wick than paraffin.
- Rapeseed and blended waxes behave differently.
- Additives change the melt pool behaviour.
Fragrance Load & Composition
It’s not just percentage – Fragrance composition matters.
- Heavy vanillin or resinous oils can clog a wick
- Higher fragrance loads often require wicking up
- Some essential oils burn hotter
Vessel Diameter
Wicks are selected based on internal diameter, not volume.
A 30cl and a 20cl may need the same wick if their diameters match.
Dye usage
Heavily dyed candles can require a stronger wick.
Cure Time
Testing too early leads to inaccurate results.
- Soy wax: Ideally 10-14 days
- Blends: Differ. Always check manufacturers’ guidance.
Testing before full cure can give misleading performance data.
How To Conduct a Proper Wick Test
This is where many candle makers go wrong – the only test is one wick. To find the perfect wick can take a few tries.
Step 1: Choose 3 wick sizes
Always test:
- Your expected size
- One size down
- One size up.
This will give you a clear performance comparison.
Check out our blog post on our Wick Size Chart to find out more.
Step 2: Keep everything else identical
Pour test candles using:
- The same wax batch
- The same fragrance percentage
- The same vessel
- The same pour temperature
The only variable you need to change is the wick.
Step 3: Allow to cure
Label the candle with:
- Wick size
- Pour Date
- Fragrance Load
Do not rush this step. This will allow the wax and fragrance to combine fully.
Step 4: Conduct a controlled burn test:
Follow a structured schedule:
- Burn for 4 hours
- Allow full cool down
- Repeat
- Continue testing throughout the candle’s life.
Record after every burn:
- Melt pool diameter
- Flame height
- Mushrooming
- Sooting
- Container tempature
- Time to full melt pool.
We recommend running multiple burn times to get as much data as possible.
How To Read Your Results
You may need to wick up if:
- The melt pool doesn’t reach the edge within 3-4 hours
- Tunnelling begins
- Flame appears weak
- Scent throw feels underpowered
You may need to wick down:
- Flame is excessively tall
- Heavy mushrooming forms
- Soot appears on the vessel
- The melt pool is too deep
- The container becomes very hot
You are looking for:
- Full melt pool by hour 3-4
- Stable, moderate flame
- Minimal carbon buildup
- No visible soot
- Safe container temperature
Common Wick Test Mistakes
Even experienced makers make these errors:
- Testing only one wick size
- Changing fragrance load mid-test
- Burning for longer than 4 hours
- Not allowing a full cool-down
- Not testing to the bottom of the candle
- Failing to document results
Good record-keeping builds a repeatable system for your brand.
Why Every New Fragrance Needs Testing
Even if everything else is the same, a new fragrance oil can completely alter burn behaviour.
There are no safe shortcuts here. Reformulating without testing increases risk and product returns.
Frequently Asked Questions & Answers about Wick Testing
How long should you leave candles to cure?
The recommended time is:
- Paraffin: 24-48 hours
- ProSoy: 10-14 days
- ParaSoy: 5-7 days
- KeraSoy: 10-14 days
- CocoPro: 7-10 days
Do I need to re-test if I change the fragrance percentage?
Absolutely.
Increasing fragrance load can:
- Slow down capillary flow
- Reduce flame stability
- Require wicking up
Reducing fragrance load can:
- Increase burn rate
- Lead to overheating
- Require wicking down
Even a 1–2% change can impact performance.
Should I only test one wick size?
No — always test at least three:
- Your expected size
- One size down
- One size up
This comparison approach prevents costly bulk purchases of the wrong wick size and allows you to make data-led decisions.
Wick sample packs are designed specifically for this purpose — enabling structured testing before committing to full reels.
What’s the ideal flame height during testing?
You’re looking for a stable, moderate flame — typically around 10–15mm.
Signs of imbalance:
- Excessively tall, dancing flame → likely need to wick down
- Small, struggling flame → may need to wick up
Consistency across multiple burns matters more than a single observation.
How hot is too hot for a container?
If the vessel becomes uncomfortably hot to hold, your wick may be too large.
Professional makers often use an infrared thermometer during testing. Monitoring container temperature improves safety confidence and supports compliance documentation.
Can I speed up the cure time?
There is no safe shortcut to curing.
Lids, warmer storage, or airflow will not accelerate fragrance binding in a meaningful way. Rushing this stage often results in inaccurate testing and wasted materials.
Time is part of the process.