Top 7 Tips for Efficient Candle Testing
Candle testing is by far the biggest investment in your workshop. Unsafe candles can make the news – and not in a good way.
Every candle test conducted with industry standard methods can take anywhere from a few hours for a tealight, to 80 or more hours for larger candles.
Unfortunately, testing is a necessary part of running a reputable candle shop. Yes, it takes a lot of time and persistence, but it keeps you from the headlines and ensures your customers get to enjoy an amazing selection of incredible candles.
Instead of droning through boring tests all the time, here are 7 tips for making the most of your test strategy!
1 Simplify
Candle making is all about finding answers to questions. Questions that are simpler to ask and often easier to answer. It’s also less frustrating when there are fewer questions in play.
Every candle you sell needs test data somewhere in your archive. Proof that you validated the candle design for safety and (hopefully) performance.
Working backwards from your product line, this means you tested every unique combination of wax, fragrance, wick, and container. If you don’t have a few decisions made before creating those, you’ll end up overwhelmed by test data.
Before testing, decide what wax and candle type you want to use and stick with it.
Removing two major factors from the equation means exponentially less candle testing. If you have no idea what wax or container you want to use, your process could spiral into an abyss of uncertainty and revisions.
It’s hard to “decide” on some things because they seem ultra important, but making some early assumptions will ease the initial process. If it doesn’t work out, those issues become obvious fairly quickly and you can pivot.
A majority of candle lines use a small variety of containers and wax blends, but a much larger selection of fragrances and wicks inside them. Picking the foundation for your designs ahead of time ensures your candle testing is focused on meaningful data. Meaningful data turns into faster information.
2 Label and record everything
Notes are critical to being successful. You’ll never remember everything. Might as well let a notepad do the heavy lifting for you. Or if you’re really progressive, a digital notepad. Preferably cloud based.
Taking good notes is crucial to understanding two things:
- What you did
- What you need to do
Your experience and professional aptitude as a candle maker fills in the gap between #1 and #2. Over time, you’ll learn how to interpret process, conditions, and test results to build a solid action plan.
In the meantime, record literally everything you can. If you’re lost about where to start, split your notes into three sections.
Container Specifications
Use this section to identify the primary traits of the container you’re using, such as:
- Description and source
- Diameter and height
- Empty volume
- Wax unit weight
Tracking this allows you to quickly determine how good your assumptions on wick choice and wax weight are.
Wax Batching
Record everything about a particular batch of wax you’re using to make candles. Consider each batch of wax you create as a unique “event”, and capture the following information:
- Batch identification number (BIN)
- Wax selection (or blend)
- Weight of wax(es)
- Strength and weight of fragrance oil(s)
- Temperature management plan (max, FO, and pour)
- Cooling rate (time from max temperature to pour temperature)
- Ambient conditions (temperature and humidity)
- Date of event
- Source or supplier for wax and fragrance, including lot numbers
Candle Testing
Each batch of wax is used to create one or more candles. Use this section to track each candle through its lifecycle. Write down and record:
- Candle identification number. Every candle should have one – use painters tape to identify and track.
- Wax batch used to create this.
- Wick size
- Cure time (time to first burn after pour)
- Candle testing criteria and all testing events
- Whether this design failed or passed the safety tests
Whatever you record, make sure the information is helpful to making decisions around candle design. It’s easy to record extraneous information thinking it might be helpful later, and sometimes it is! You’ll figure out what you need for your systems over time so if you wonder whether or not you should write something down stay on the safe side and do it!
3 Find baseline wicks before adding anything else
Remember: everything added affects everything added. Candles are a complete system operating in harmony. Every component impacts the safety and performance of the candle in some way.
Too much fragrance can upset the fuel delivery. An improperly sized wick can snuff itself out or grow to unsafe proportions, and wonky containers can make or break the ability for an otherwise perfect candle to throw fragrance.
Everything in candle making is a progression that starts with the candle type and wax selection.
If you made a candle with a CD 10 wick, 6% fragrance load, and NatureWax C-3 soy in a 2.5″ diameter glass container, it’s unlikely to work well in a 3″ aluminum tin. The only thing that changed was the wax.
Similarly, using an HTP 73 wick in a 2.5″ diameter glass container with a 3% fragrance load may work wonders with palm wax but fail completely with GW 464.
Container and wax are the foundation of any candle design. Once you select a container type for your candle, assuming it’s easily sourced and scales, it’s unlikely to change behavior. The same is not true for wax.
You cannot build an intelligent foundation for your candle design if you don’t understand how your wax works by itself in your chosen “container” (container can mean different candle types too). It is imperative to determine which wick works for your bare naked wax.
Before you go off gallivanting with different fragrances and colors, perform entire safety tests with your chosen wax blend and container until you know exactly which wicks work in it. Don’t add fragrance or color. Burn it all the way from the top until end of life or failure.
Remember that adding anything more to your candle complicates the entire system, so it’s crucial that you’re able to identify the root cause of failed candle testing. Once you understand a baseline CD 10 wick works well for your bare candle, you’ll know the added fragrance oil is the reason a CD 10 failed.
4 Re-test new lots of wax to confirm your assumptions
A perfect world involves wax that doesn’t change (among other, more noble ideas). Unfortunately, the nature of wax development means there’s occasionally enough drift in the final raw candle wax it would be foolish to trust.
Having the baseline wick for your wax helps reduce issues with product drift because it introduces a level of quality control.
Every time you receive a new batch of wax from a different lot, best practice suggests you create a candle using your baseline wick and make sure it still performs like you expect.
If it does, carry on. If it doesn’t, you know something changed in the foundation of your candle design and you’ll have to re-formulate to accommodate the change. This is far better than knowing something changed because your customer’s complain about it.
Quality control measures like this allow you to respond quickly to changes through informed identification of root cause.
5 Test every unique fragrance oil
It’s easy to think you can shortcut the process if you’ve identified one working combination of fragrance, wax, and wick. Unfortunately, physics isn’t on the side of the candle maker!
Every single fragrance oil behaves different. Some burn hot, some clog the wick, and some outright refuse to work in some systems. It’s okay, but it means more work for candle makers to ensure each fragrance oil gets safety and performance tested, even if the container and wax stay the same.
It’s not uncommon for three fragrances to require three different wicks, or even wick series, in similar wax and container systems. The nature of candle making means everything added impacts everything added. Fragrances are relatively unpredictable, so make sure to complete an entire test for every unique fragrance oil in your product line.
Shortcuts have a nasty habit of showing up later. Remember this: if you think you never have time to do it right the first time, you’ll still find the time to do it twice later. Impatience is not a virtue!
6 Always include industry standard test
While not the law, industry standards serve as voluntary standards for candle makers as it pertains to testing. ASTM F 2417 is the primary source for standard candle testing. It outlines procedures, provides clear definitions for all components of the standard, and characterizes all fail points of a burn test.
…but the procedures outlined within aren’t exactly realistic for how customers really consume their candles. For instance, we know that wick trimming is recommended but most people ignore this. Well, the wick testing guidelines in ASTM F 2417 require you to trim the wick before each 4-hour burn.
4 hours? Yep. Figuring out the average candle use time would be an interesting statistic, but it’s likely all over the map.
Some people start a candle then run out the door 20 minutes later, blowing it out before it has a chance to burn. Others may burn the candle all day as they quarantine in their office, well exceeding the 4-hour limit commonly printed on candle instruction cards.
But you still need to follow the industry standard. Well, technically you don’t have to, but if you ignore it your candle making operation is at risk for making a product against industry standards. In a Product Liability case this won’t look too great.
Testing your candles in unique and alternative patterns is a good way to understand the limits and behavior for more realistic consumption. In fact, it’s darn near Best Practice to conduct variance and chaos candle testing. But no matter what you do, always have a formal industry standard burn test for every candle in your records, just in case.
And don’t only do it once. Try and test your candle design with relative frequency if you’re pumping out hundreds through various lots of wax. A starting point may be 1 in every 100 or 200 candles should be quality tested to make sure you’re within the allowed margins of your product’s expected performance.
Voluntary is expected in the case of problems
Also conduct quality of life tests – variance, chaos, etc
7 Use alternate test hacks to iterate faster
There is no substitute for a formal candle safety test, but there are a few suggestions for establishing the right wick sets. Creating an entire candle every time you need to test a new system can be tiresome, especially if you have no idea where to start with wicks.
It’s extra frustrating when you’re trying out new containers and you don’t want to waste materials. The following tips are great for helping reduce waste and get you closer to the right materials, but they don’t count as a formal safety test. You still need to create a full-sized candle and burn it all the way from start to end of life or failure.
Sometimes it’s faster to iterate with entire candles because you don’t have to “re-make” them if one of the following methods ends up working out on the first shot. Your mileage may vary.
Pour only half a candle
Container candles burn in an interesting way. Near the top, most of the heat generated by the flame dissipates into the air which keeps the container temperature under control.
As the candle burns deeper into the container, more air is trapped in the walls. The flame heats nearby air inside the container which stirs local currents and actually increases the flame temperature by feeding it more oxygen.
This extra heat makes wicks that appear to work near the top of the candle fail in the bottom half. Pouring half a candle accomplishes two things:
- You only need half the materials to make the candle.
- Your test occurs in the toughest part of the candle to size wicks for.
For the most part, passing the safety tests in the second half of a container means the wick is right, but not always. The dynamics of a burn at the top of a candle can influence the characteristics in the bottom half. Soy is particularly susceptible to transforming when deeper melt pools in the top half reach into the bottom.
Testing the entire candle is important, even if you pass the bottom half.
Continuously replace the wick
Replacing the wick is a great strategy for trying out several wicks in a single candle. We’ve shot and discussed the process and technique before, but this can be done on any candle at any time. Obviously, it disqualifies that candle from formal candle testing to industry standards, but can speed up testing dramatically by allowing you to replace the only part you have to.
Pour wickless candles
The final hack is creating candles without a wick. Why? If you just need to try out a bunch of wicks it’s much easier to insert it without a tab.
After pouring a wickless candle, simply use a skewer or chopstick to pierce a pilot hole where you want a wick (or wicks). Install the wick and burn! Don’t worry about the extra gaps – they’re filled in quickly with melted wax and shouldn’t affect the burn.
A word of caution – wicks you place in the pilot hole won’t have a tab. This doesn’t affect anything until near the end of the candle when the tab supports the wick when all remaining wax is liquid. If you aren’t careful, the wick may “tip over” into the melted wax and extinguish itself.
Messy.
It’s also risky in shorter jars or aluminum tins since the melt pool reaches down near the middle much faster. If you’re concerned, you can always formally replace the wick and put a tab down, even if you’re starting with a wickless candle.
Conclusion
Like these tips? Have other ideas you want shared with the world? Send us an email or tag us on Instagram and we’ll see what we can do.
Shortcuts add up. The safety of your customers and yourself are not worth skipping the line at the candle testing station. As a profession we have a duty to make sure everything created by our hands and processes is trustworthy and doesn’t become an unfortunate statistic.
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How to Conduct a Basic Burn Test
