My 25 Kg Batch Produces Different Results From My 5 Kg Batch — How Do I Determine Whether the Problem Is Mixing Time, Temperature or Holding Time?

Three suspects, and two things to clear first

When a 25 kg batch behaves differently from a 5 kg batch of the same formula, mixing time, fragrance-addition temperature and holding time are the three usual suspects. They are also tangled together: a bigger mass stays hot longer, which pushes the addition temperature up, which you might offset by stirring longer, which extends the hold. Change all three at once on the next batch and you will never know which one mattered.

Before investigating any of them, clear two simpler explanations. First, confirm the wax and oil were from the same lots as the 5 kg batch, or check what changed if they were not; a new raw-material lot can produce a difference that looks like a process fault. Second, confirm the weights by mass balance: for 25 kg at 8% of total, that is 23 kg of wax and 2 kg of oil, not 25 kg of wax plus 2 kg, which would be a 27 kg batch at 7.41%.

If both are clean, you have a genuine process difference, and the three suspects can be separated with evidence you mostly already have.

Reading the fingerprint of each cause

Each of the three causes tends to show a different pattern across the 125 candles a 25 kg batch fills at 200 g. The patterns are not proof on their own, but they tell you which experiment to run first.

Citrus Lemon, the oil in this example, is a helpful teacher here. Its product page notes that citrus top notes are volatile and fade faster than warmer families. If heat or holding time is the problem, a lemon batch tends to show it sooner than a vanilla or woody one.

Put the two batch records side by side

Pull out the batch sheets for the 5 kg and the 25 kg batches and compare them line by line. If key lines are missing, reconstruct them from phone photographs, timestamps and memory, and mark them as estimates. The readings below are one maker's example records, shown to illustrate the comparison; they are not targets.

In this record, every suspect changed. The addition temperature was higher, the stirring effort per kilogram was lower, and the hold was far longer. That is typical of a first 25 kg batch, and it is exactly why you need an experiment rather than an argument.

A four-batch experiment that isolates each factor

Temperature and holding time can be tested cheaply at 1 kg, because you can impose the large batch's conditions on a small one. Mixing is different: a 1 kg batch is easy to stir, so it cannot reproduce a mixing failure. You test mixing through position sampling on the large batch itself.

Make A to D on the same day from the same wax bag and oil bottle, keep the melter off its maximum setting, and check every temperature with a thermometer because of the melter's stated ±10°C display deviation. Cure them together for at least the stated 48–72 hours, then rank cold and hot throw blind. If B matches D, temperature is doing the damage. If C matches D, it is the hold. If A to D are all fine but the 25 kg retains vary by position, it is mixing.

Prices use CSI 464 at ₹507.40 per kg, the same at every pack size, and the 1 kg Citrus Lemon pack. The experiment costs about a sixth of one batch, and the candles it produces are still usable as your own retained references.

Deciding the fate of the 125 candles

Hold the full batch until the experiment reports. If the cause turns out to be addition temperature, the whole batch is likely to be uniformly weaker, and remelting will not recover what was lost. Decide whether it meets your standard as it stands, in a burn test run in a closed room and never unattended, or whether it becomes seconds or a write-off.

If the cause is holding time, the early part of the pour may be fine. Release by position only after a burn test confirms it. If the cause is mixing, a full remelt and thorough blend of all 125 candles together, with no extra oil, can bring the jars back towards the average, provided the remelt itself is kept short and below the oil's flashpoint.

One control per suspect

Once you know which factor failed, write a control for it, and keep the other two as they were so you can see the effect cleanly on the next batch.

If meeting the hold limit at 25 kg is not possible with your equipment, the simplest control is to scent the wax in portions close to the size you have already validated. Do not raise the percentage to compensate for heat loss; you will pay more for oil and still have a process that behaves differently every time the batch size changes.

Where this page fits

CSI already has guides that cover parts of this question. This page covers the failure investigation for the question above; these go deeper on the rest:

Three things to buy for this job

Frequently asked questions