I Start With 20 Kg of Wax at the Correct Pouring Temperature but Production Takes Two Hours — How Do I Maintain Consistent Conditions From First Pour to Last?

Consistent conditions means more than one temperature

You start the run right: 20 kg of scented wax at the correct pouring temperature. Two hours later the last candle leaves the pitcher. The question is not only whether the wax is still warm enough. Over those two hours, five conditions can drift apart between the first candle and the last, and each one needs its own control.

Most makers control the first row and forget the rest. Then they get a batch where the pour temperature was fine throughout, yet candle 100 still differs from candle 1, and they blame the oil.

Worked example: the two-hour time budget

The batch is 20 kg of scented wax at 8% of total weight: 18.4 kg of CSI 464 and 1.6 kg of Roasted Coffee. At 200 g per candle that is 100 candles before losses. You buy the wax as two 10 kg packs at ₹5,074.00 each (₹10,148.00, leaving 1.6 kg over for the next batch). The oil comes as 1 kg at ₹3,738.00, 500 g at ₹1,890.00 and 100 g at ₹390.00, which is ₹6,018.00. The wax used is 18.4 × ₹507.40 = ₹9,336.16, so the batch holds ₹15,354.16 of wax and oil (₹9,336.16 + ₹6,018.00). A batch that goes wrong in the second hour has already absorbed half of that.

Now the time. One hundred candles in 120 minutes is one candle every 1.2 minutes on average. The 600 ml steel pitcher holds about 540 g of melted wax when full (600 ml × roughly 0.9 g per ml), but a pitcher filled to the brim is hard to pour cleanly, so plan on a working fill of about 400 g. That is two candles per fill and 50 fills across the run, or one fill every 2.4 minutes. Those figures are arithmetic from your batch and a suggested working fill, not a rule; weigh one of your own fills and redo the sum.

Written out like this, the run stops being 'two hours of pouring' and becomes 50 identical cycles. Each cycle is a draw, a pour into two jars, and a return to the melter. That is the unit you control.

Choose the run design before you choose a temperature

There are three sensible ways to structure a 20 kg run. None is right for every workshop, and the honest choice depends on how long your team actually takes, not how long it should take.

If your 1 kg test was poured within minutes of adding the oil and your production candles sit for two hours, you have changed a variable your test never covered. The second and third designs keep production closer to what you actually approved.

Time your real team, not your plan

Before you choose, time an ordinary run. Most workshops lose minutes in ways that never appear in the plan: a tray of jars that has not been wicked, a label roll that runs out, a refill that waits because the operator is answering the phone. If your '120 minutes' is really 150, the last candles see half an hour more hold than you thought, and the single-batch design looks worse than it is on paper. Write down the start and finish of every fill for one run and the gaps become obvious. Often the cheapest improvement is to prepare every jar, wick and tray before the oil goes in, so the clock starts only when there is nothing left to do but pour. The batch then finishes sooner, the hold is shorter, and you may find that one 20 kg batch is perfectly adequate once the idle minutes are gone.

Prove the design with one logged run

If the fill-50 candles match fill 1 and the control, your single-batch design is fine and you can stop worrying about the clock. If fill 50 differs and the control matches fill 1, hold time is a real factor in your system and one of the other designs earns its extra weighing.

If the last batch already drifted

Whatever you decide for the held-back candles, write the decision on that batch's sheet with the candle numbers involved. When the next logged run comes back clean, that note is what tells you the change in design fixed the problem rather than a lucky day.

Write the controls into the SOP

Once the logged run has told you which design works, write the controls down so the next operator does not rely on memory. The SOP line for a 20 kg run should state: the design (single batch, halves or portions); the hold setting, checked with a thermometer at the start and every ten fills as a suggested starting point; the minimum pitcher temperature at the pour; a gentle stir before each draw; the working pitcher fill in grams; and the maximum time scented wax may be held before it goes back for review. The imported melter's display carries a stated ±10°C deviation, so every temperature in the SOP is read with a separate thermometer. Keep the melter on its own supply, never run it at maximum to catch up, and keep hands and sleeves clear of the rim during refills.

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