My Lavender Fragrance Oil Has Changed Colour and Smell After Six Months — Should I Test It Before Using It in Another Candle Batch?

Short answer: quarantine, then test

You have noticed two changes in the same oil: it looks different and it smells different. Either can happen during storage, and each has innocent and less innocent explanations. Together they are a strong enough signal that the oil should not go into production until you have checked it.

Quarantine is simple. Put a clear "do not use — under test" label on the bottle, move it away from the production shelf, and record the lot code, the date the pack was first opened and the date you noticed the change. Nothing else needs to happen today. What matters is that nobody pours it into a batch out of habit while you are deciding.

CSI's Lavender page describes the oil as single-note lavender with fresh lavender at the top, a herbal green middle and a soft musk base. It publishes no shelf life, no storage conditions and no ageing data, so there is no published date to check against. The comparison has to be physical: your stored oil against a reference.

What might have changed in six months

The colour

Many fragrance oils darken with age, exposure to air or light, or warmth. Darkening alone does not prove the oil is unusable. It is a prompt to look more closely, and in your case the smell has given you a second reason.

The smell

A fresh lavender opening relies on lighter materials, which are generally more volatile and can be more prone to oxidation than the musky base. After six months of opening and storage, a lavender oil may smell less fresh and more herbal or musky. That alone may still be usable. A sharp, sour, harsh or solvent-like edge is different: it points toward oxidation or contamination, and it is the result most likely to show up in a finished candle.

The bottle

Check the conditions the oil lived in. Was it near a window, under a roof sheet, beside the melter or opened often with the cap left off? Was it decanted into a container that may not suit it? Your answers will not change today's decision, but they will change how you store the next pack.

The test, step by step

Why the test is worth it: the numbers

Use your own stock as the example. Say 600 g of the 1 kg pack is left. At ₹5,221.00 per kg, Lavender is ₹5.221 per g, so the remaining oil is worth 600 g × ₹5.221 = ₹3,132.60. At 16 g per 200 g candle at 8%, it would scent 600 ÷ 16 = 37.5, so 37 candles.

Those 37 candles carry far more than oil. Using the series' reference cost of ₹253.60 for a 200 g CSI 464 Lavender candle in a matte jar with an Eco C1 wick, the materials in them come to 37 × ₹253.60 = ₹9,383.20, before packaging, labels, labour, shipping and GST. A failed batch loses all of it, plus the customers who buy the candles. Against that, the fresh 100 g reference costs ₹540.00 and the test candles a small share of it.

Reading the result

If every line passes, release the oil, note the result on the bottle and use it soon; it has already shown it can change. If the only difference is a slightly softer top with no off-note, you may accept it for products where that matters less, but record the decision and do not mix it with fresh stock.

If the oil shows an off-note, layers, sediment or a clearly different hot throw, keep it out of production. Ask on WhatsApp (+91 7397976926) for the IFRA certificate, MSDS and any storage or shelf-life guidance for that oil and lot, and get the answer in writing. Do not try to correct it with other materials.

Review how the pack was stored

Whatever the test shows, the six months that led to it are worth reviewing, because the next pack will live in the same place. Start with temperature. Put a min/max thermometer where the oil sits and leave it for a week; storerooms near roofs, windows, kitchens or the melter can run much warmer than the room feels. Warmth speeds both evaporation and oxidation.

Then light. A bottle on an open shelf by a window, or under strong lighting for long hours, is exposed in a way a bottle in a closed cupboard is not. Then air: how many times was the pack opened, was the cap left off during weighing, and how much of the container was air for the last few months? Finally contamination: were stirrers, pipettes or scoops dipped into the oil, and was unused oil poured back?

Write down what you find and change one or two things for the next pack: a cooler, darker cupboard, pouring into a beaker instead of dipping, decanting the second half into smaller well-sealed suitable containers, or simply buying a pack you will finish sooner. Six months from now, you will be able to tell whether the change worked, because you will have a retained sample to compare against.

Size the next order to six-month evidence

This episode is evidence about your own usage. If a pack took longer than six months to finish and changed before you finished it, the next pack should be smaller or used faster. Lavender is listed at 100 g, 500 g and 1 kg; choose the size you can finish well inside the time your own tests show the oil stays acceptable, even when the larger pack is cheaper per gram.

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