Will Reheating a Failed Candle Batch Change the Fragrance Enough That I Need to Repeat Hot-Throw Testing?

Three things changed when you reworked the batch

You remelted a sweating batch, perhaps diluted it, and poured it again. The new candles look clean and smell fine in the jar. The question is whether you can assume they throw like the candles you originally approved. You cannot, for three separate reasons.

Heat history. Fragrance oils are mixtures, and some of their materials are lighter and more volatile than others. Holding scented wax hot for a second time can drive off some of those lighter materials. How much depends on the oil, the temperature and how long the wax stays hot, and no general figure exists. Fresh top notes — citrus, some herbal and aquatic openings — are usually the first to suffer.

Cure. Remelting restarts the cure. CSI's oil pages state minimum cures before burn testing — 48–72 hours in soy for most oils, 72–96 hours for Royal Oud. Testing a reworked candle the day after pouring tells you little.

Load. If you diluted to stop the sweating, there is less oil per gram of wax. That alone can change throw — sometimes not at all, sometimes noticeably.

Separate heat from load with a fresh control

If the reworked candle throws weaker, you need to know why, because the fix differs. Weak because of load points to a different oil or a slightly higher tested load. Weak because of heat history points to a gentler remelt next time. A single extra candle tells them apart.

Pour a fresh control: new wax, new oil, the same jar, the same wick, at the reworked batch's final load. It has the new load but none of the extra heat. Then compare three candles side by side:

Reworked equal to control: reheating did not cost anything measurable, and any difference from the original is the load. Reworked weaker than control: the extra heat history is costing you throw.

Example: a Citrus Lemon batch reworked to 8%

Here is an illustrative case. A maker's Citrus Lemon candles in CSI 464 sweated at 10% and were diluted to 8% of total weight. Citrus is the family most exposed to heat history, and CSI's own Citrus Lemon page notes that citrus top notes are volatile and fade faster than warmer families, recommending the full 48–72 hour cure and the upper end of the stated range. That page advice was written for fresh candles, not reworked ones, so it does not override the sweat: 10% already failed in this wax, and 8% is where the test must happen.

Three fresh controls at 8% need 16 g of oil and 184 g of wax each. Their material cost, with wax at the 10 kg rate:

That excludes jars, wicks, packaging and GST. In practice you buy packs: the 50 g Citrus Lemon sample at ₹170.00 holds the 48 g needed, a 1 kg pack of CSI 464 is ₹507.40, and an Eco C1 20-pack is ₹118.00. The point is the scale of it — a few hundred rupees to know whether a large reworked batch still does its job.

The throw test record

Use a written record so the comparison is honest. The schedule and room set-up below are suggested starting points; keep them identical for every candle in the set.

Burn one candle at a time in the same closed room, with a break and fresh air between, and have more than one person note what they smell, ideally without knowing which candle is which. Never leave a burning test candle unattended.

Keeping heat history short next time

If the comparison shows the rework cost you throw, the lesson is about how the batch was reheated, and it applies to every future rescue. None of the points below come with CSI figures; they are general practice to adapt and record.

Record the temperatures and holding times on the batch sheet alongside the throw results. Over two or three reworks you will learn which of your oils tolerate a second heating and which do not — information that also tells you which scents are worth rescuing and which are better scrapped and re-made fresh.

Acting on the result

Whatever the outcome, the reworked batch does not go out on the strength of the original approval. It earns its own.

Add the result to the batch sheet: the reworked batch number, the final load, the date of each throw check, and a one-line verdict against the control. The next time a batch of this oil fails, you will already know how it behaves after a second heating — and whether a rework is worth the effort at all.

Where this page fits

CSI already has guides that cover parts of this question. This page answers one sweating decision; these cover the neighbouring questions:

Three things to buy for this fix

Frequently asked questions