I'm Scaling From 2 Kg to 25 Kg of Scented Wax — How Do I Make Sure Fragrance Oil Is Distributed Uniformly Throughout the Entire Batch?

Why oil distributes unevenly in large batches

When you pour 160 g of oil into 1.84 kg of wax, the jug is small enough that the oil meets most of the wax within seconds and a spoon finishes the job. When 2 kg of oil meets 23 kg of wax, the oil enters at one point in a deep vessel. Some of it spreads, some sits near where it landed, and the parts of the batch furthest from the stirring, usually the base and the corners, receive less until they are deliberately worked.

Fragrance oil does dissolve into melted wax, so given enough mixing a batch becomes uniform. The practical risk is not that it can never mix, but that it has not yet mixed when you start pouring, and that a batch left unstirred between pitcher fills never gets the chance to finish. The fix is a routine, not a machine.

What uneven looks like in finished candles

Uneven distribution rarely shows as an obvious fault. The candles look the same. The difference appears only when they burn: a run of candles that throw well, another run that seems muted, sometimes a candle that sweats a little oil at the surface because it received more than its share. Because the jars look identical, the problem often reaches customers before it reaches you. That is why the verification step later on this page is not optional at 25 kg.

Plan 25 kg as two halves

CSI's largest Electric Wax Melter is rated at 20 kg, so 25 kg of scented wax does not fit in a single CSI vessel. Even if you have a larger container from elsewhere, splitting has real advantages at this size. Each half is shallower and easier to stir to the bottom. Each half spends less time hot after the oil goes in. And if something goes wrong with one half, you have lost half a batch, not all of it.

At 8% of total weight, the full 25 kg is 23 kg of wax and 2 kg of oil. Each 12.5 kg half is 11.5 kg of wax and 1 kg of oil. Weigh each half's oil separately into its own tared container before you start, so the second half is never dosed from whatever happens to be left in a bottle.

Adding the oil so it disperses as it enters

How oil goes in matters more than most makers expect. Tipping a full kilogram in at once creates a concentrated pool. Adding it in a thin, steady stream while someone stirs spreads it across the moving wax from the first second. If you are working alone, add it in several portions, stirring through the full depth between each.

Confirm the wax temperature with a thermometer before starting. Add at the wax maker's stated temperature; for Eco Soy CSI 400 that is 80–90°C, and for other waxes it is whatever the maker states. The melter's display is not a substitute. CSI's large melter states a ±10°C deviation on its display, and some CSI oils have published flashpoints below 100°C, so adding oil at the melter's maximum is never the right shortcut.

If a helper does the stirring, show them the full-depth pattern once and watch the first half. People new to large batches tend to stir the surface, because that is the part they can see moving. A simple instruction such as 'touch the base on every stroke' fixes most of it.

Stirring the full depth, and keeping it mixed

A full-depth stir means the paddle reaches the base, sweeps along it, rises through the centre and scrapes the walls. A stir that only moves the upper half of the batch looks convincing from above and leaves the base under-dosed. CSI does not sell long mixing paddles; if you buy one, look for something smooth, heat-resistant and long enough to reach the base of your vessel with your hand well clear of the wax, and keep separate paddles for strongly different fragrance families.

How long? There is no published mixing time for 12.5 kg. A sensible starting point to validate is to stir until the base and walls have been swept several times and no streaks or oily patches are visible at the surface, then keep going for a little longer, and record the total. Your burn results will tell you whether that time was enough. Use a timer rather than a feeling; stirring always feels longer than it is.

Pay attention to the walls. Wax in contact with the sides of the vessel is where temperature differs most from the centre, and a thicker layer there is harder to mix than the fluid centre. Scraping the walls as part of every stir brings that layer back into the batch.

Then keep it mixed. Before every pitcher fill, give the batch a few full-depth strokes. It takes seconds and protects the last candle as much as the first.

Verifying the result before you trust the routine

If the test fails, resist the urge to explain it away by nose alone. Change one thing, either a longer stir, oil added more slowly or more frequent re-stirs, and repeat the same comparison with the next half. Changing several things at once leaves you with a better batch but no idea which change made the difference, and you will need to know when the next fragrance behaves differently.

Only when this test passes should the routine go onto your production card. From then on, repeat a lighter version of it, perhaps just first and last candles, on each new fragrance or wax lot.

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:

Three things to buy for this job

Frequently asked questions