How To Measure Hot Throw
You can judge a candle’s pure design by two criteria: safety and performance.
Safety is structural and objective. Conducting a safety test, or wick test, tells you if a candle is good or bad. Most tests cover a variety of criteria for the candle to pass during a certain length burn.
If the candle fails to meet one, it’s a failed design. Simple. Binary. There’s no room for interpretation with most of the thresholds in a basic burn test.
But judging performance isn’t so easy!
“Performance” in this case refers to how good a candle’s scent is. Unlike safety testing, performance testing doesn’t have a great framework or criteria. Even more scientific approaches, like gas-chromatography-olfactometry rely on a human being with a trained nose… much like a wine sommelier.
The fact of the matter is that judging scent throw is hard to put in a scientific box.
But that’s okay! Hot throw represents the art in candle making, much like colors and labels and such, whereas safety tests are scientific. If you’ve ever wanted a craft full of creative potential, making candles is a perfect candidate.
But how do you ensure your candle smells good? In this piece we’ll cover a simple framework and process you can use to “measure” the quality of your hot throw: the BLO Test.
BLO Test
BLO stands for:
- Bathroom
- Living room
- Others
Judging hot throw requires a decent opinion, but the BLO test provides a framework to form them in that accounts for several factors.
As long as human judgement is involved, measuring hot throw won’t ever be perfect.
However, implementing the BLO framework allows you to normalize human judgement and account for many factors that impact scent.
Before you begin performance testing, make sure you have a safe candle. One that passes a typical burn test for your criteria or the industry standard criteria.
No matter how good your scent throw is, safety always comes first.
The following procedure assumes you’ve successfully passed a safety test and cured the candle appropriately.
Before starting the BLO test, gather a timer (or a phone) and something to take small notes on. Sticky notes work fine here.
Bathroom Test
Unless you’re living like a superstar, most bathrooms clock in at a reasonably small size compared to other rooms.
Most even circulate air pretty well, which plays enormously into hot throw success.
Almost any candle with a slight bit of hot throw can fill a bathroom, which makes it a perfect starter area for testing hot throw.
If you can’t obtain a reasonable amount of throw in areas like this, you probably need to make some adjustments to your design – a different subject altogether.
The first stage of the BLO test is to burn your candle in a bathroom for a relatively normal amount of time. Burn as you expect an average user would, but every hour walk near or into the bathroom and rate the scent throw from 1 to 10.
There isn’t a wrong answer, just your opinion on how well the candle is performing.
Don’t like the 1-10 scale? Use whatever you want to judge the hot throw. Alternate ideas include:
- Strong – Average – Weak
- A – B – C – D -F
- Good – Bad
Make the scale as simple or complicated as you want, but check in on the candle every hour it burns and rate it.
Burn the candle 1 to 3 times in the bathroom.
If you’re satisfied with the results, move on to the Living room portion of the test.
Living Room Test
The living room portion of the test means any room bigger than a bathroom.
You can use a living room, but you can also move to a kitchen, an indoor porch, or really anything with more than one door.
Achieving a scent throw in a bathroom gives you an initial tease into how well the candle works, but larger rooms help you understand their true potential.
Same thing. Burn the candle and grade it every hour. The only twist – move the candle’s location to a different area of the room every hour too.
Moving the candle helps account for potential differences in local and global air currents.
Hot throw thrives when a room has great airflow through it, as the aromatic compounds given off by the wick “catch a ride” into the nostrils of the lucky people nearby.
Some candle makers give up too soon on a candle when they can’t smell it in a particular room or area, when they may have performed just fine if they had moved them a few feet.
During the Living room test you may experience this too.
If the candle fails to live up to your desired expectations after a few more burn sessions, you might consider revising the design, but you can also pursue the next portion of the test anyways since it accounts for your biased and skewed opinion (all opinions on scent are skewed, after all).
Move to the next and final portion of the test if you’re satisfied with the Living room results.
Others
Sharing your candle designs is perhaps one of the more fulfilling aspects of candle making.
The benefit, of course, is you can leverage people’s opinions of a candle in exchange for, well, the candle.
In the final part of the test, create fresh copies of the candle design that passed BL scent testing, and give one to as many people as you want.
Ask for their thoughts.
You can be as specific in this request as you want, though it tends to work better if you let them know you need honest feedback in any form after they’ve burned the candle a few times.
Most importantly, you should encourage them to burn it normally as they would with any other candle.
But you’re free to send them a candle with a grading sheet if you really want some cold, hard data. Nothing wrong with that!
When the feedback starts coming in, don’t live or die by a single person’s thoughts.
Studies have shown that the average of a group tends to be close to the “right answer”.
Scent has no right answer, but hopefully the group you’ve chosen represents about what your customers would be.
But don’t overthink it. The real intention of Others is to keep your own opinions honest. After all, if you’re cranking out candles all day it’s possible to become a bit nose blind – a bias of it’s own.
More opinions are better, so take Others as far as you feel comfortable.
Send out a minimum of two candles, and don’t forget to follow up.
If feedback tends to be positive, you’ve likely passed the BLO test and you can feel a lot better about the design you’re putting out there!
Conclusion
A perfect framework for measuring hot throw doesn’t exist because scent is ultimately an opinion. What may overwhelm Joey might delight Rachel, but offend Chandler. Aroma is a spectrum and an art. Never forget that.
Bathrooms are the basic test for whether the candle can throw at all.
Living rooms help account for air flow and larger areas, but still fail to capture the real differences in people’s sensitivities and scent preferences.
Testing with others ensure you gather a somewhat aggregate opinion of more people, which helps form an average opinion from users that burn the candle in a variety of situations and styles.
At the end of the day, you don’t need to incorporate a framework. Some candle makers have great noses and don’t worry so much about what people think, which is a valid approach too!
The BLO test exists for those that want to build security and remove bias from the equation as much as they can.
Additional overhead and testing sometimes outweighs the uncertainty of forgoing scent testing altogether.
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