One Soy Wax Produces More Cosmetic Rejects than Another — How Do I Include Rework and Rejected Candles in the True Wax Cost?

Divide by the share you can sell — then the cheaper wax has a reject budget

The rule is the one this whole cluster uses: cost per saleable candle = material per poured candle ÷ (1 − reject rate) + rework labour. Rejects divide, they do not add, because every candle you can sell has to carry its share of the ones you could not. A 10% reject rate does not add 10% to your cost — it adds 11.11%. A 20% rate adds 25%.

Applied to two real CSI waxes, the answer is more forgiving than most makers expect. A 200 g candle with British Rose Fragrance Oil at 8% costs ₹203.95 in Natural Soy Pearl Wax and ₹236.00 in Luxury Soy Wax Chunks at 5 kg rates — a gap of ₹32.05 a poured candle. If Chunks ran at an example 2% reject rate, Soy Pearl could reject up to 15.3% of its candles before its cost per saleable candle caught up. Add an example ₹15.00 of pouring labour per candle, which rejects also waste, and the headroom is 14.5%.

That headroom is the cheaper wax's reject budget. It is not a forecast — CSI publishes no reject data for any wax, and nothing here suggests either wax produces more rejects than the other. It is the number your own pilot is measured against. If the cheaper wax stays inside its budget, it is the cheaper candle even with its rejects. If it does not, the per-kilo saving was an illusion.

The reject grid: cost per saleable candle, rate by rate

The lead table runs both waxes from zero to 20% rejects. The first pair of cost columns is materials only; the second adds an example ₹15.00 of pouring and finishing labour per poured candle — a figure you replace with your own, and one that rejects destroy just as surely as wax.

Read across a row to compare the waxes at the same reject rate, or diagonally to compare them at different rates. Soy Pearl at 15% (₹239.94) is still just below Chunks at 2% (₹240.82) on materials. At 20% it is well above. So a rough rule for this pair and oil: if your pilot shows Soy Pearl rejecting more than about 13–15 candles in a hundred while Chunks rejects two, the cheaper wax is the dearer candle.

The wax gap is the same ₹32.05 a candle whatever the oil — but with an expensive oil, each reject throws away more, so the same gap buys fewer rejects. With a perfume-inspired oil the cheaper wax can afford only a few points more rejects than the dearer one. That is the commercial reason premium SKUs deserve the most consistent wax you can find. Putting a financial value on consistency follows that thought into planning and overproduction.

What one reject actually throws away

It helps to see a single reject in rupees. Here is one Soy Pearl candle with British Rose at 8%, poured and then scrapped:

Two lessons. First, the wax is a minority of what a reject wastes — ₹78.16 of ₹203.95 in materials here — which is why the cheaper wax's per-kilo saving does not stretch as far as it seems. Second, when you find a reject matters: one caught at the pouring bench costs materials and pouring time; one caught after labelling and packing costs all of that plus the packaging. Inspect before you pack. Costing heat-gun correction covers the rejects you can rescue, and the ₹30-a-kilo rework comparison runs the rescue maths at 1,000 candles a month.

A month with rejects and rework, worked

Here is a full example month, with every rate labelled as an example you replace. 400 candles are poured in each wax. In the Soy Pearl month 8% are scrapped and 6% reworked at an example ₹8.00 of labour each; in the Chunks month 2% are scrapped and none reworked. Labour is the example ₹15.00 per poured candle.

In this example the cheaper wax still wins, by ₹17.61 a saleable candle, but it also produces 24 fewer candles to sell from the same pouring effort. That second number matters when you are capacity-limited — during festive production, for example, when every pouring hour is spoken for. Whether fewer rejects improve margin brings selling price into the picture, and whether easier pouring justifies a dearer wax looks at the labour side.

Measuring reject rates honestly: the pilot

A reject rate is a frequency, so it needs a batch. With three candles, one reject is 33%; with twenty, it is 5%. The pilot below pours twenty of each wax, in two pours of ten so that one bad pour does not decide the result, and judges every candle against a cosmetic standard written before anything is poured. Because the candles are real production candles, the ones that pass go into stock.

The priced pilot

40 candles, 20 per wax. Wax: 3,680 g of each, 3,864.0 g with a 5% pour-loss allowance (a working assumption). Oil: 640 g, 672.0 g with allowance. Because the passing candles are sold, the true cost of the pilot is only the rejects and your time — but you need the cash for the whole kit up front.

That is ₹239.91 per candle poured, close to the production material cost because the packs are nearly production packs. British Rose is one of the oils where buying bigger genuinely lowers the per-gram price (₹3.42 at 100 g, ₹3.19 at 500 g, ₹3.07 at 1 kg), which is why the 1 × 500 g + 2 × 100 g works out cheapest here. Most CSI oils are priced almost linearly above 100 g.

The decision rule, ending in a purchase

With the example pilot — Soy Pearl at 8% scrap and 6% rework, Chunks at 2% — the cheaper wax still wins and the purchase is Natural Soy Pearl Wax in 5 kg bags at ₹2,124.00: a 400-candle month needs 73.60 kg of wax, 15 bags. But keep the pilot's rates in your batch book and recompute every month. A cheaper wax whose reject rate creeps up in summer can cross its budget without anyone noticing, which is exactly what seasonal qualification is designed to catch.

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