I Received Two Containers With the Same Fragrance Batch Number but They Smell Slightly Different Immediately After Opening — What Should I Do Before Mixing Them?

Why the first sniff is the least reliable

Every sealed container of fragrance oil has a pocket of air above the liquid. Over days and weeks that air fills with the lightest, most volatile molecules in the blend, so the first breath when the cap comes off is weighted heavily towards the top notes. How strong that effect is depends on how full the container is, how warm it has been and how long it stood. Two containers of genuinely identical oil can therefore give noticeably different first impressions.

Your own nose adds a second distortion. After the first container, your sense of smell has already adapted to the dominant notes, so the second container tends to seem weaker, sharper or simply different. Anyone who has smelled a dozen samples in a row knows how quickly impressions blur.

A third possibility is settling. Oil that has stood still for a long time can become very slightly uneven top to bottom, particularly in a cool room. A gentle inversion before sampling removes that as a variable.

None of this means a real difference is impossible. Containers can be filled at different points of a production run, a cap liner can carry an odour, or a container can simply be mislabelled. The job at goods-in is to strip away the false causes first, so that whatever difference remains is one you can trust.

Temperature can also differ between containers in ways you would not guess. One carton may have sat against a warm wall in the delivery van while the other was shaded, and a kilogram of oil takes hours to settle to room temperature. Until both containers match, any comparison is partly a temperature comparison.

A word on the label itself. CSI's product pages do not publish lot or batch numbers, so when containers carry one it is usually a supplier's own grouping, and the method here works just as well without one. Either way, the number is the supplier's statement about how the oil was grouped. It is useful information and belongs in your record, but it is not a measurement you made.

Putting the two containers on equal terms

The timeline matters because different parts of the blend show at different times. A difference that exists only in the first minute is usually a top-note or headspace effect. One that is still clear at the hour is sitting in the heart or base and is more likely to be real.

The odd-one-out test

Side-by-side comparisons invite you to find a difference because you expect one. An odd-one-out round avoids that. Prepare three coded strips: two from one container and one from the other, in random order. The assessor's only job is to say which strip is the odd one. If there is no real difference, they will be right about one time in three by chance.

As a suggested starting point, run three rounds, varying which container supplies the pair. If the assessor picks correctly in all three, treat the difference as real. If they pick it once or not at all, the difference is unlikely to matter in a candle. Two correct out of three is a grey area; add a second assessor or move straight to comparison candles. This is a simple screening rule for a workshop, not a formal sensory standard, and you should adjust it once you see how it performs with your oils.

Worked example: two kilograms of Lavender

A maker receives two 1 kg containers of Lavender carrying the same batch number on the supplier's label. Each costs ₹5,221.00, so together they represent 2 × ₹5,221.00 = ₹10,442.00 of oil. At 8% of a 200 g candle, each candle takes 16 g of oil, so the pair fills 2,000 ÷ 16 = 125 candles, and at ₹5,221.00 ÷ 1,000 = ₹5.221 per gram each candle carries 16 × ₹5.221 = ₹83.54 of fragrance.

On opening, the second container seems sharper and more herbal. The product page describes the oil as single-note lavender with a fresh lavender top, a herbal green middle and a soft musk base, and rates it as Strong. A sharper, greener first impression is exactly what a headspace difference in the top and middle notes would look like.

The maker rests both containers overnight, inverts them, and runs three odd-one-out rounds at 15 minutes. The assessor picks correctly once. At the hour, the coded strips are indistinguishable. The record reads: first-sniff difference, not reproduced on strips, containers combined, retained sample taken from the combined oil. Total cost: a few strips and an evening's patience.

Had the assessor picked the odd strip all three times, and the difference still been present at the hour, the decision would have been different. Each container would stay separate and labelled, and one comparison candle from each, made with the same jar, wick, load and cure, would show whether the difference survives into wax.

Deciding, recording and talking to the supplier

If you do find a persistent difference, tell the supplier with the batch number, photographs of both labels, your strip record and any candle results. For CSI orders, WhatsApp +91 7397976926 is the route. Ask whether both containers were filled from the same material and write down what they say. That answer is information; your strip and candle results remain the evidence.

And if one container turns out to be different in wax, it stays separate whoever supplied it, including us. Blending it in at a small ratio might make the difference hard to notice, but it would also make it impossible to explain if a customer notices first.

Keep the result, whichever way it goes. A short entry saying first-sniff difference, not reproduced, combined on this date, becomes valuable the next time the same thing happens. After two or three deliveries you will know whether this oil routinely shows a sharp headspace on opening, and your goods-in step can become quicker without becoming careless.

It is also worth noting which container you used first after combining or sequencing, and when. If a customer later mentions that a candle smells greener than the last one they bought, you will want to know whether that candle was poured before or after the change of container.

Where this page fits

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

Three things to buy for this job

Frequently asked questions