How Do I Design a Temperature-Cycling Test That Reflects Indian Courier Conditions Without Assuming It Predicts Exact Shelf Life?

Start by writing down what the test is for

A temperature-cycling test is a tool for comparison. It can show that formula A comes through repeated warm-and-cool swings better than formula B, or that a better-sealing lid protects the scent more than the old one. It cannot tell you that a candle will last eight months, and it should never be written up as if it did.

So the first line of your protocol should be its purpose, in plain words. For example: "To compare the fragrance retention of three candle formulas after temperature cycles based on our measured courier conditions. This test does not establish a shelf life." That sentence protects you from your own optimism later, when a good result tempts you to print a bold claim on a label.

Step one: measure your real courier conditions

"Indian courier conditions" is not one thing. A parcel from Pune to Mumbai in December and a parcel from Pune to a hot northern city in May live in different worlds. Design from data, not from a guess.

Step two: translate the profile into cabinet cycles

Now turn the route summary into something a controlled cabinet can repeat. Choose the warm setting close to the measured parcel peaks, the cool setting close to your normal room, and a cycle length that resembles the warm and cool periods you logged. If a typical journey showed two or three warm spells, a few cycles represent one journey; more cycles represent several journeys or a harsher route.

Every value you pick is a suggested starting point and must be recorded with its reason. The warm phase belongs in a controlled cabinet or warm room, watched and logged on a thermometer; kitchen ovens, microwaves, stoves, car boots and flames are all ruled out.

Resist the urge to crank the warm setting far above what your parcels saw to "speed things up". A setting far beyond real conditions can produce failures — soft tops, heavy sweating — that never occur in practice, and can rank formulas in an order that does not hold on the road.

Step three: decide the samples and arms

A sound design has three arms for each formula you compare:

Cycled: candles go through the cabinet cycles. Stay-home twins: candles from the same pour sit at room conditions for the same calendar time. Real-ship check: a few candles travel an actual instrumented route and come back, so you can see whether the cabinet result resembles reality.

Worked example: three formulas, three arms, three candles per arm = 3 × 3 × 3 = 27 candles. Add one unscented control to the cycled arm and one to the stay-home arm, from the same wax, to show what the wax does on its own.

Costed with one example formula, a 180 g candle in our 200 ml clear salsa jar with lug cap, CSI 464, CSI Lavender at 8% of total candle weight (165.6 g wax plus 14.4 g oil) and an Eco C1 wick: wax 165.6 × ₹0.5074 = ₹84.03; oil 14.4 × ₹5.221 = ₹75.18; jar ₹1,475.00 ÷ 50 = ₹29.50 at the 50-pack; wick ₹5.90. Per candle: ₹84.03 + ₹75.18 + ₹29.50 + ₹5.90 = ₹194.61. Twenty-seven candles: 27 × ₹194.61 = ₹5,254.47, excluding packaging, labour, shipping and GST.

The salsa jar holds 200 ml to the brim; at roughly 0.9 g per ml for melted soy wax, 180 g is a sensible estimate of a working fill, but confirm by weighing a real pour to your fill line.

Step four: write the protocol down

Put the whole design on one sheet so that the test can be repeated next season, or for the next new oil, in exactly the same way. Below is a template with example entries.

Step five: use the result, and only the result

If one formula clearly beats the others in the cycled arm and the real-ship check agrees, you have good grounds to choose it for products that travel. If the real-ship check disagrees with the cabinet, trust the road and adjust the cycle for next time.

If no formula passes, the answer may be packaging or dispatch practice rather than fragrance: insulated packing, keeping stock cool before it leaves, or avoiding the hottest routes on peak days. Re-run the same protocol with the packaging change as the only variable.

Treat the protocol as a living document. Each season, add the new logger readings to the route summary. If your parcels now travel further, or you have moved to a different courier or a new packing method, the cycle that represented your routes last year may not represent them now. Update the settings, note the date and reason, and re-run the comparison for your most important lines.

Use the same sheet for every new oil you consider. A protocol is only valuable if candidates are judged by one rule; a new citrus tested under a gentler cycle than the old one has been given an unfair advantage. Keep completed sheets, scores and logger printouts together, so that a decision taken today can be explained to a stockist or a business partner next year.

Keep the real-time evidence running alongside. Retained candles stored at your normal conditions, checked at intervals you choose, are what support any shelf-life or "best within" wording you print. The cycling test sits beside that evidence; it never replaces it.

And before you scale a winning oil, ask us on WhatsApp (+91 7397976926) for its IFRA certificate, MSDS and any storage or shelf-life guidance for the lot, in writing. Our fragrance-oil pages publish no shelf life or storage temperature, and no oil pack above 1 kg is listed, so plan bulk quantities as multiples of 1 kg or a quote.

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:

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