My 10 Kg Batch Looks Perfect but Does Not Smell as Strong as My 1 Kg Test — Should I Verify Fragrance Weighing and Distribution Before Increasing the Percentage?

What a good-looking 10 kg batch has and has not proved

Smooth tops, even colour and clean glass tell you the wax set well. They say nothing about how many grams of fragrance oil ended up in each jar. A 10 kg batch can be cosmetically flawless and still carry less oil than your 1 kg test, or carry the right amount spread unevenly across 50 candles.

When a production batch smells weaker than the test, there are only four families of explanation. Less oil went in than you think. The right amount went in but did not spread evenly. The oil went in evenly but the process changed it, usually through longer heat exposure. Or the comparison itself is unfair: different cure age, different jar, a tired nose, or a test candle that was stronger than you remember.

Increasing the percentage treats only the first family, and only by luck. If the real cause is distribution, a higher load gives you some candles that are now too strong and some that are still weak, and you have paid for more oil to get there. That is why weighing and distribution come first.

Step one: prove how much oil actually went into the wax

You do not need a laboratory to check the dose. You need a mass balance: the weight that left the bottle, minus what stayed behind in anything it passed through. Work through these checks in order, writing each figure on the batch sheet as you go.

Here is how the errors stack in a real case. A maker planned a 10 kg Lavender batch at 8%, meaning 9.2 kg of wax and 800 g of oil. The bottle-by-difference check showed only 740 g had left the bottle, because the beaker had been tared with a splash already in it. Separately, the wax had been weighed as a full 10 kg rather than 9.2 kg.

Nothing about this batch would look wrong. Yet it is running at roughly 6.9% against an approved 8%, which is a large enough gap to notice in a room. The fix here is a weighing procedure, not a new percentage.

Step two: prove whether the oil is spread evenly

If the mass balance says the correct dose went in, the next question is whether every candle received its share. You cannot answer that by sniffing whichever candle is nearest. You need candles that you can trace back to a point in the pour.

Number the jars in pour order as you fill them, and keep a note of which pitcher refill each came from. After the page's stated minimum cure (48–72 h for soy on the Lavender product page), pull a small set from the beginning, middle and end of the run. The sample positions below are a suggested starting point to validate for your own batch size.

Cold-throw the samples blind: have someone else code the lids, and rank them without knowing which is which. Then burn-test a matching set in the same room, one at a time or in separate rooms, never unattended. If the beginning, middle and end candles are equally weak, the problem is quantity or process. If they rank in a clear order, it is distribution, and the companion page on first-versus-last candles explains the mechanisms in detail.

What to do with the 50 candles already poured

Put the whole batch on hold until both checks are finished. Do not sell the strongest-looking cases first, because you do not yet know whether strength varies by position.

If the reconciliation shows a clean under-dose and the candles are uniform, you have a choice. You can release them as they are if they still burn safely and meet a standard you are willing to put your name on, or you can rework. Rework means remelting the batch and topping up the oil. On the example above, the top-up to reach 8% of total is found from (740 + x) ÷ (10,740 + x) = 0.08, which gives 0.92x = 119.2 and x = about 129.6 g of Lavender. Add it below the oil's flashpoint, which is not published on the Lavender page, so ask for the MSDS on WhatsApp before you reheat.

If the checks show uneven distribution, adding oil makes it worse. The only true rework is to remelt everything into one vessel, blend thoroughly, and re-pour, and remelting 50 jars is slow, messy work. For a small batch, it can be cheaper to write it off than to spend a day recovering it. Either way, record the decision and the reason on the batch sheet.

Why the percentage is the last lever you pull

Raising the load feels like the obvious fix because it is a single number. It is also the most expensive fix on the list, and the only one that increases your cost on every future batch.

Prices use the 1 kg Lavender pack and CSI 464 at ₹507.40 per kg, the same rate at every pack size. At 10% you are also at the top of the stated load range on the product page, which leaves no headroom for later adjustment and may change how the wick behaves. That is a new formula needing its own wick test, not a quick correction.

Controls that stop this happening on the next batch

Most of the fixes cost nothing but a few lines on the batch sheet. Write the full-bottle and empty-bottle weights for every oil addition. Write the wax weight as a separate line, calculated from the total batch weight, never assumed. Record how many candles you filled, because an unexpected count is the earliest warning of a mis-weighed batch.

Check your scale at the start of each production day with the same reference object, and note the reading. Keep three retained candles from every batch, labelled with batch number and pour position, so that the next complaint can be traced rather than guessed. And keep one simple rule in writing: nobody changes the fragrance percentage until the mass balance and the beginning-middle-end check have both been done.

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