Why heat is rarely the only suspect

A weak candle is a result, not a diagnosis. At least five things upstream of the burn can each make a candle smell weaker than you expected, and several of them are cheaper and quicker to rule out than temperature. The order below is the order we suggest checking, from free to paid. It is a working checklist, not a statistic. We do not have data on how often each cause is responsible, and nobody selling fragrance oil does either.

Look at the first row twice. A large number of "weak" candles are simply under-loaded. If your notebook says "1 kg wax + 80 g oil", you have made a 7.41% candle, and the scent is lower than the 8% you think you tested. The fix is arithmetic: for a true 8% of the finished weight on 1 kg of wax, add 86.96 g, or weigh 920 g of wax and 80 g of oil for a 1,000 g batch. I'm Making a 1 Kg Soy Wax Batch at 8% Fragrance Load — Do I Add 80 g Fragrance Oil to 1 Kg Wax or Should the 8% be Calculated from the Total Finished Candle Weight? works through both conventions in full, and I'm Making 10 Kg of Scented Candles at 8% Fragrance Load — How Do I Calculate the Exact Wax and Fragrance Quantities Without Accidentally Making a 10.8 Kg Batch? shows the same trap at 10 kg.

The second and third rows catch most of the rest. A soy candle burned the day after pouring is not the candle your customer will light. The melt pool matters just as much. Scent leaves a candle mainly from the liquid wax around the wick, so a pool that tunnels leaves most of the fragrance locked in solid wax. These three checks cost nothing. Do them before you spend money proving a temperature theory.

What heat can do to a fragrance oil

Candle fragrance oils are built from many aroma materials, usually with a carrier. Perfumers group them loosely into top, middle and base notes by how quickly they evaporate. Top notes are the bright, light, fast-moving materials: citrus peel, fresh green notes, some herbal notes. Base notes are heavier and slower: woods, resins, vanilla-type materials, musks. The mechanism commonly described is simple. The hotter the wax and the longer it stays hot with an open surface, the more of the fastest-evaporating material can leave before the candle sets. Prolonged high heat can also change some sensitive materials. Neither effect is a CSI measurement, and neither comes with a percentage we can give you.

Why is temperature alone not the whole answer? Because exposure is a product of several things. A few seconds above range in a narrow jug is not the same as twenty minutes on a direct flame in a wide pan. The table sets out the factors makers can actually control.

Two points follow. First, the fragrance you lose to heat is most likely to be the bright opening, not the whole scent. A heat-damaged candle is more often described as flatter or duller than as scentless. If your candle smells of almost nothing at all, look harder at load and wick. Second, citrus-led and fresh oils have more top-note material to lose than heavy woods and vanillas. That is general perfumery knowledge, not a claim about any individual CSI oil. My Citrus Candle Smells Fresh When Cold but the Top Notes Disappear Quickly While Burning — Why Are Some Fragrance Notes Harder to Retain in Candles? covers why citrus top notes are hard to keep in a candle.

The temperatures on record — and the ones that are not

We will be exact here, because this is where a lot of candle advice gets invented. The only CSI temperature on record is CSI's CSI 464 guidance, 80–90°C — confirm on the product page. That figure comes from CSI's own earlier guide for Luxury Soy Wax CSI 464, and the product page is the authority if it differs. For Luxury Soy Wax Chunks, Natural Soy Pearl Wax, Premium Coconut Soy Wax CSI 468 and every other wax we sell, follow the wax maker's instructions. If the product page does not show them, ask us on WhatsApp and we will pass on what the wax maker states.

Why so cautious? Because the addition temperature is a property of the wax system, not a universal number. Different soy blends are formulated to take up oil and set in different ways, and their makers test for that. A figure copied from a forum for a different wax is not safer than no figure. It just looks more precise. The same goes for fragrance suppliers who print a single mixing temperature for all their oils. When their advice and the wax maker's disagree, My Fragrance Supplier and Wax Supplier Recommend Different Mixing Temperatures — Which Recommendation Should I Prioritise When Developing My Formula? explains which to follow and how to test both.

The split test that settles it

The test isolates temperature by holding everything else still. It uses four 200 g candles at an 8% load of the finished weight: 16 g of oil and 184 g of wax each. The worked example uses CSI 464 because it is the one wax with a CSI temperature on record, and Lavender from a 100 g bottle at ₹5.40 a gram. Swap in your own wax and oil. The structure stays the same.

Reading the result is straightforward. If both B candles clearly beat both A candles, heat was part of the problem, and your fix is a thermometer and a batch log. If the pairs score the same, temperature is not your problem, and you have saved yourself from changing the wrong variable. If the scores are mixed, the difference is smaller than the noise in your test. Then look at load, wick and cure, which are usually the larger effects.

The maths behind the weak batch

Here is the batch in the question, costed. Say you melted 1 kg of CSI 464 at ₹507.40 and added 80 g of Lavender from a 100 g bottle, which is ₹432.00 of oil. That made 1,080 g of scented wax: 5 candles of 200 g with 80 g left over. The load on the finished weight was 7.41%. If the candles are weak, part of the reason may be that they were never at 8%.

The gap looks small, 6.96 g at 8%, but it is the same size as the difference many makers are trying to detect when they compare temperatures. That is why load comes first in the suspect list. If you recalculate and your candles were under target, fix that before you run the split test, or both arms will simply be weak together.

The material cost excludes labour, packaging, freight and GST. It also leaves you four sellable-looking candles, although you should keep at least one from each arm as a retained sample. Compare ₹1,025.85 with the value of a full production run made with a heat problem you never proved or disproved. At ₹256.46 of material per candle, a 50-candle run carries ₹12,823.08 of material. The test is cheap insurance.

Here are the three products this page's maths uses. The wax cards show how many 200 g candles each pack makes at 184 g of wax per candle.

Where the rest of this cluster fits

This page is the hub for temperature and mixing. Each question below has its own page, so the answer here stays short. Find your symptom and follow the link.

Two pages in the next part of the cluster pick up where this one stops. If your first candles from a batch smell weaker than your last, My First Candles from a Production Batch Smell Weaker than the Last Ones — Could the Fragrance Oil be Settling or Mixing Unevenly? covers settling and uneven mixing across a pour. If you want one written process that makes every batch behave like your approved test candle, How Do I Create a Repeatable Fragrance Mixing and Curing Protocol so Every Commercial Batch Performs Like the Approved Test Candle? builds it.

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