How to Test Candle Scent Throw Fairly

A fair scent test holds everything the same except the thing you are testing, and it does not rely on the nose of the person who lit the candle. Hot throw is the scent while the candle burns. CandleScience says to judge it after the candle has burned at least two hours but no more than four. Never leave a lit candle unattended or out of sight while you test.

What are the steps?

1. Cure first. Cure times depend on the wax, so see How long to cure a candle before burning.
2. Settle the wick before you judge scent. CandleScience says to finish the burn test and settle on the wick first. Otherwise a candle can seem great for the first few burns and then turn out to be over-wicked as the wax drops. It also says several candles burning at once is not a good place to judge hot throw.
3. Pick one room and keep it. Use the same draft-free room for every candle. For causes of weak throw, including room size, see Why does my candle smell weak when it burns?
4. Light one candle, keep someone with it, and rest your nose. Midwest Fragrance says that if you sit in the room with a burning candle, your nose "shuts off" from olfactory fatigue, so you may not smell a candle that is throwing well. Its method has you light the candle, leave the room and close the door. Do not do that part. The National Candle Association says never to leave a burning candle unattended, and CandleScience says the same for test candles. So a helper stays with the flame the whole time, and you come in every 1 to 2 hours to judge. With no helper, put the candle out before you leave the room, then come back and judge what is left in the air. That is my own workaround, not a supplier's method, and it is a weaker reading. The point is a rested nose, not an empty room.
5. Ask other people, blind. CandleScience says no two people have the same sense of smell, and recommends getting opinions from a few people in a few different settings. Set it up like this:

• A helper picks a random letter for each jar.
• The helper writes the key (letter = which recipe) on paper and seals it in an envelope.
• The jars look the same: same jar, same lid, nothing on the outside that tells them apart. Put the letter on the bottom or on a tag.
• Nobody opens the key until every score is in.

1. Score on a scale you define once. See the scale below. House of Scent suggests standing a few feet from the candle, then further back, to see how far the scent carries.
2. Write it down. Note the time since lighting, who scored, the room, the wick and the load.

Write the scale down once

Pick the spots before you start, mark them with tape, and score at the same spot every time. This is our example scale, not a standard.

A blank score sheet, one row per score:

Worked example: load only, blind, on two days

The wick is already settled, so this test changes the load and nothing else. Three candles, each with an 8 oz (227 g) fill, wax and oil together. The load is a percent of the wax weight, and the wax is fill / (1 + load). All numbers are examples.

Check each: 7.55 + 0.45 = 8.00, 7.41 + 0.59 = 8.00, 7.27 + 0.73 = 8.00. Use 10 percent only if your wax maker's sheet allows that load.

Three people score each jar at the 2 hour mark, on two different days. One candle at a time. Each cell is day 1 / day 2.

Rater 3's two days disagree by 2 points on X (4, then 2), and the ranking flips between days. That rater is not reliable this round. Drop them or re-run them, and do not average them in. With raters 1 and 2 only:

The ranking is Q, then M, then X on both days, so you can trust it. Q beats M by 0.50 and 1.50 points. Two raters is a small sample, so add a rater before you decide. Then open the key, and check Q's flame, pool and jar heat before you pick it.

Why do the numbers need to match?

• The nose. CandleScience says a fragrance you have smelled for a long time likely smells weaker to you than to others, and that medications, illness and nose blindness change perception.
• The candle. CandleScience says a full melt pool is fundamental to strong hot throw, so a candle with a stalled pool is not a fair test of the oil.

Common mistakes

• Sitting next to the candle and judging by your own nose.
• Judging an uncured candle.
• Testing the wick and the scent in the same round.
• Burning five candles in one room and comparing.
• Comparing a small candle in a big room with a large one in a small room.
• Changing the scale between tests.
• Adding more fragrance oil first. Midwest says more oil does not always mean a stronger throw, and too much can weaken it.

Questions

How far from the candle should I stand?

House of Scent says to stand a few feet away, then further back, and see whether the scent is noticeable. That page gives no more detail, and I found no set distance in another source.

How long should I wait before I judge?

CandleScience says to judge after at least two hours of burning and no more than four. Midwest re-checks every 1 to 2 hours. Keep someone with the flame between checks.

Can I test alone?

Yes, but never by walking away from a lit candle. Put the flame out before you step out to rest your nose, as in step 4, and expect a weaker reading from only one nose. CandleScience suggests asking a few people. A second person who does not know which candle is which helps the most, and can watch the flame too.