Should I Keep an Approved Reference Sample of Each Fragrance Oil Lot to Compare Incoming Wholesale Deliveries?

Yes — and the reason is that memory is not a reference

When a wholesale delivery arrives, you will compare it with something. If that something is your memory of the last lot, the comparison is close to worthless. Noses fatigue, familiarity dulls a scent you smell every day, and a warm afternoon makes everything seem stronger than a cool morning. A retained reference sample replaces memory with an object: a small, sealed quantity of the oil you approved, stored so it changes as little as you can manage, and opened only when you need to judge something against it.

So the short answer is yes. Keep two kinds of reference for every fragrance oil you use commercially. The first is an approved master reference — a sample from the lot that passed your full candle testing, the one your product was built on. The second is a lot retain — a sample of every lot you receive afterwards, kept for as long as candles made from it could still be in a customer's home or on a stockist's shelf.

The master answers “is the new delivery still the oil I approved?”. The lot retain answers a different question months later: “when this customer complained, was the oil in their candle already different on the day it arrived?”. You need both, because each one answers a question the other cannot.

How much to retain, and what it costs

A reference sample only has to be big enough for its job. For a bottle-to-bottle smell comparison on blotters you need very little. If you also want to make a pair of comparison candles from the reference later, you need enough oil for those candles at your load. A practical starting point is 20 g per lot for oil-only comparison, and enough for two candles at your load if you want candle-level checks — that is 32 g for two 200 g candles at 8%, since each one carries 16 g of oil. These are suggested starting quantities, not a standard.

Here is what that costs on CSI's Woody Oud, bought as 1 kg packs at ₹4,531.20:

The reference candle line is worked out as 184 × ₹0.5074 = ₹93.36 for wax, 16 × ₹4.5312 = ₹72.50 for oil, then ₹93.36 + ₹72.50 + ₹70.80 + ₹5.90 = ₹242.56. It excludes packaging, labels, labour, shipping and GST. Twelve lot retains a year cost less than one tenth of the oil in a single 250-candle batch (the batch size is an example). That is the whole economic argument: retained samples are cheap insurance against a batch you cannot explain.

Storing the reference so it stays a reference

A reference that ages faster than your working stock gives false alarms; one that ages slower gives false comfort. The aim is to store it under conditions at least as protective as your bulk oil, and to touch it as rarely as possible. General good practice for fragrance oils applies: sealed, cool, dark, upright, away from windows, roof sheets and heat sources, with as little air above the liquid as practical.

CSI's oil product pages do not publish a shelf life, a storage temperature or ageing data for any oil, and they do not say how oils are packed. Before you decide how long a retained sample remains a fair benchmark, ask on WhatsApp (+91 7397976926) for the IFRA certificate, the MSDS and any storage or shelf-life guidance for that specific oil and lot — and keep the reply in writing alongside your retain register.

Using the reference when a wholesale delivery arrives

When a new delivery comes in, the comparison should be blind and side by side. Put a drop of the master and a drop of the new lot on separate, coded smelling strips, let the alcohol-like first lift settle for a few minutes, and smell them in a neutral room. If someone else codes the strips, you will not know which is which. Smell again after an hour, when the heart and base are more evident. Note colour and clarity of both bottles in daylight against a white card.

One caution matters more than any other. Your master reference ages too. Even sealed and dark, it is not frozen in time. If the new lot smells brighter than a two-year-old master, the master may have softened rather than the new lot being “wrong”. That is why the previous lot retain is also useful: compare the new lot with the master and with the most recent retain, and if the new lot sits between them or close to the recent one, the difference is less likely to be a supplier change.

Retaining candles as well as oil

Oil in a bottle and oil in wax do not age the same way, so a complete reference system also keeps a couple of finished candles from each production batch. Store them lidded, in the packaging your customers receive, at the position where your stock really sits. When a customer says a candle has lost its scent after four months, you can pick up the retained candle from the same batch and compare it with a freshly made candle from your master oil. That separates three possibilities: the lot was different from the start, storage has changed the candle, or the customer's conditions differ from yours.

If you make retained candles, also keep one unscented control candle in the same wax stored alongside them. If the control develops an odour of its own, part of what you are smelling in the scented candles may be the wax, not the fragrance.

None of this tells you how long the fragrance will last, and you should not promise customers that a candle will smell unchanged for any period. What a reference system gives you is evidence: the ability to show what the oil and candle were like on day one, and to make decisions on comparison rather than recollection.

Where this page fits

CSI already has guides that cover parts of this question. This page answers one fragrance-ageing decision; these cover the neighbouring questions:

Three things to buy for this decision

Frequently asked questions