My Premium Soy Wax Costs More per Kg but Produces Fewer Rejects — How Do I Calculate Whether It Is Actually Cheaper than My Budget Wax?

Cost per sellable candle

Rejects — frosting you will not sell, sinkholes, wet spots, poor adhesion, cracked tops, crooked wicks — are part of every production run. The question here is not what causes them, which varies with wax, jar, temperature and technique, but how to price them. The rule is simple: if you pour 100 candles and 8 are rejects, the 92 good ones have to carry the cost of all 100. Cost per sellable candle is therefore the poured cost divided by (1 − reject rate).

The table shows two things. At the same reject rate, the cheaper wax is always cheaper per sellable candle — the rows never cross. And each point of reject rate adds roughly 1% to the cost of every good candle, a little more as rates rise. So the only way a dearer wax becomes the cheaper choice is if it rejects fewer candles than the budget wax — enough fewer to cover its price gap. That is the break-even the next section computes.

The break-even reject rate

Let C_p and C_b be the cost per poured candle in the premium and budget wax, and r_p and r_b their reject rates. The budget wax is cheaper per sellable candle while C_b ÷ (1 − r_b) is below C_p ÷ (1 − r_p). Solving for the budget wax's reject rate at which the two are equal:

In this example the price gap is wide enough that the cheaper wax can reject 10.5% points more than the premium one before it loses. CSI 464, closer in price to Chunks, has less room: about 5.5% points. These figures move with your recipe — a dearer oil or jar raises both poured costs by the same rupees and narrows the gap in percentage terms, so a reject is more expensive and the premium wax needs less of an advantage to win.

Salvage changes the answer

Not every reject is a total loss. Cosmetic rejects can often be remelted and repoured, and the jar cleaned and reused; the wick, sticker and labour are usually lost, and some fragrance may be too (how much is not something we can publish). If a reject's recoverable value is R, cost per sellable candle becomes (C − r × R) ÷ (1 − r). As an example, suppose you recover 90% of the wax and reuse the jar.

Salvage shrinks the cost of rejects for both waxes, and it helps the wax with more rejects most, because it has more to recover. With salvage, the gap in this example widens from ₹14.95 to ₹23.75 per sellable candle in the cheaper wax's favour. But salvage is not free: remelting takes time and energy, a repoured candle can have its own defects, and a jar that has to be scraped and washed is labour. If you count those honestly, R is lower than the materials suggest.

The break-even formula extends to salvage too. If T is the premium wax's cost per sellable candle (with its own salvage), the budget wax matches it at a reject rate of (T − C_b) ÷ (T − R_b), where R_b is the budget wax's salvage value per reject. In the example, T is ₹301.65, C_b ₹266.96 and R_b ₹141.14, so the cheaper wax can reject up to 21.6% before it loses — against 12.5% without salvage. The more you can recover from a reject, the less a lower reject rate is worth paying for.

Rejects at volume

At volume, rejects show up as extra pours. To deliver 400 sellable candles a month you must pour more than 400. The extra pours cost materials, time and melter capacity — which matters most in the weeks before Diwali, when capacity is the constraint.

One more cost belongs here: escapes, the defective candles that are not caught and reach a customer. Each costs a replacement, a courier and some goodwill — an example ₹150.00 per escape, far more than a reject caught at the bench. If a wax's defects are harder to spot before dispatch, count escapes separately. At an example one escape per 100 candles sold, that is ₹1.50 on every sellable candle. The breakage post handles the transit side of the same problem.

Measuring your reject rate

To start a side-by-side trial, 12 candles in each of two waxes with one oil is enough to set up the process and the log. It will not give you a reliable rate on its own — keep logging through normal production for that. The list below covers 12 Chunks and 12 Soy Pearl 200 g candles in Bergamot Amber with 4% extra wax and oil.

Where this fits: the poured cost comes from the ten-line cost sheet, and a reject allowance belongs in every price test — ₹499, ₹399, ₹799 and ₹1,499. A load change can move your reject rate too, which the 8% → 10% post flags. And if you are about to scale up, the one-batch wax post covers why keeping wax consistent across a large order helps keep rejects predictable.

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