I Scaled My Candle Formula From 1 Kg to 20 Kg and Kept Fragrance at Exactly 8% — Why Could the Finished Candles Still Smell Different?

Weaker and different are separate problems

A candle that is simply weaker usually points to less effective fragrance: a load calculation slip, a batch that sat hot for longer, or oil that was not evenly mixed. A candle that smells different, with a sweeter or flatter or sharper character, a missing top note or a heavier base, points somewhere more specific. Either the balance of the blend changed during processing, or the materials themselves were not the same materials you tested.

Start by writing down what the difference is, in your own words, before anyone else smells it. 'Less fresh opening', 'more woody', 'the floral has gone' are useful notes. 'Different' on its own is not, because it gives you nothing to test against.

It also helps to agree on who judges. One person's nose, the same time of day, the same room. Two people with different descriptions of the same candle can send an investigation in two directions at once.

How heat can change the balance of a blend

Fragrance oils are mixtures. Some components are light and leave readily when warm; others are heavy and stay. When scented wax is held hot, the light components leave first. A short hold barely registers. A long hold, like the time 20 kg of wax can stay warm while you pour a hundred candles, can remove enough of the lighter material that the remaining blend reads heavier and less bright. That is why the result can be different rather than just weaker.

This is also why a high published flashpoint is not reassurance about scent. CSI's Sandalwood lists a flashpoint of 203°C and Jasmine 185°C. Those figures matter for safety, because they tell you when vapour could ignite, but lighter notes can still evaporate from wax far below them. Keep both ideas separate: flashpoint governs fire risk, hold time governs scent loss.

Check whether it is literally a different oil

At 1 kg you probably tested from a 100 g sample. At 20 kg you need 1.6 kg of oil. Using Sandalwood as an example, that might be a 1 kg container at ₹5,026.80, a 500 g container at ₹2,513.40 and a 100 g container at ₹502.68. Three containers can mean up to three production lots, and your 20 kg batch becomes a blend of them. Fragrance lots are designed to match, but small variation between any natural or blended material is normal, and you should confirm it rather than assume it.

The check is simple and costs nothing. Dip separate paper strips into the original sample and each bulk container, label them, and smell them side by side after a few minutes and again later. If the bulk oil reads differently from the sample in the bottle, the candle was always going to differ. Ask CSI on WhatsApp for the IFRA and MSDS documents for your oil if you need to confirm you have the same product and name.

Wax packs, cure time and the room

The same logic applies to wax. A 20 kg batch needs 18.4 kg of wax, which is at least two 10 kg packs. Your 1 kg test pack and the production packs may not be from the same run. Most of the time that makes no noticeable difference; occasionally it does, and the only way to know is a small test from the production packs.

Cure is the most overlooked variable of all. Fragrance continues to settle into the wax after pouring, and a candle burned before it has cured can smell sharper or thinner than one that has rested. If your 1 kg test sat on a shelf for a couple of weeks and your 20 kg candles were burned sooner, you are comparing two different stages of the same candle. Room size matters too: a test burned in a small room will seem stronger and differently balanced than one burned in a large, airy space.

Isolating the cause in one week of tests

Deciding what to change

If the materials changed, you have a choice: accept the new lot as the product going forward, or request material that matches your sample more closely. That conversation is easier with your comparison record in hand. If the process changed, the most common fix is to shorten the time the scented wax spends hot, for instance by scenting the 20 kg in two halves rather than all at once, and to confirm the addition temperature with a thermometer rather than the melter display, which on CSI's large melter carries a stated ±10°C deviation.

Splitting the scenting is easy to plan. Melt the full 18.4 kg of wax, then scent it as two 10 kg halves in turn: 9.2 kg of wax with 0.8 kg of oil, poured out completely before the second half is scented. Each half spends roughly half as long hot after the oil goes in, and each is still exactly 8%. Keep the unscented remainder at a gentle holding temperature rather than at the melter maximum while you pour the first half. Treat this split as a starting point to validate with the same blind burn, not a guaranteed cure.

If the late candles in your 20 kg run smelled flatter than the early ones, this change should close the gap. If early and late candles smelled the same as each other but still unlike the test, the split will not help, and your attention belongs on materials and cure.

Resist changing the fragrance load to chase the old character. Adding more oil makes a candle stronger; it does not restore a top note that was lost to heat. Work out which variable moved, correct that, and keep the formula you already approved.

Where this page fits

CSI already has guides that cover parts of this question. This page takes the production-floor angle; these go deeper on the rest:

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