My New Coffee Fragrance Has Stronger Cold Throw but Weaker Hot Throw Than the Previous Lot — What Should I Compare Before Approving It?

Why cold and hot throw can move in opposite directions

Cold throw and hot throw are driven by different things. Cold throw is what evaporates from a solid candle surface at room temperature, so it leans on the lighter, more volatile materials in the blend. Hot throw is what the melt pool releases once it is warm and liquid, so it depends on the whole blend, on how much of the oil is still in the wax after curing, and on how big and hot the melt pool actually gets.

That is why the two can drift apart. If a new lot of coffee carries slightly more of its bright, volatile top material and slightly less of its heavier heart and base, the cold jar can smell punchier while the lit candle feels thinner. CSI's Roasted Coffee page describes exactly that kind of layered structure: fresh coffee beans at the top, dark chocolate and espresso in the middle, vanilla and caramel in the base. A shift in balance between those layers is enough to produce your symptom.

But the lot is only one suspect. A different wick delivery that makes a smaller melt pool, candles of different ages, a warmer or cooler test room, or a change in how you added the oil can all do the same thing. Before you approve or reject the lot, you need a comparison that holds everything else still.

What to compare, and how to keep it fair

The goal is a paired test where the only difference between two candles is the oil lot.

Standardise the test room as carefully as the candles. Pick one closed room of a size similar to where customers burn candles, keep windows and fans the same for every session, and let the room air out fully between burns so the second candle is not judged against the ghost of the first. Coffee is a heavy, lingering scent, so a longer airing break than you would allow for citrus is sensible. Record the room, the time of day and roughly how warm it was; a hot afternoon and a cool morning can shift hot throw on their own.

Use at least two assessors besides yourself, and ask them to describe what they smell rather than simply score it. "Coffee at the door, chocolate near the candle" tells you far more about a shifted balance than "7 out of 10".

The comparison log

Write the results down in a way that forces the comparison. A shared sheet with both candles in adjacent columns does that better than two separate notes.

The example entries tell a clear story. The melt pools match, so the wick is not the cause. The strips already hinted at a thinner heart and base, and the candles confirm it under heat. The difference persists at day 14, so it is not simply cure time. That points to the lot, not the process.

If instead the melt pools had differed, the next step would be to repeat the pair with wicks from the other delivery swapped between candles, before saying anything to the supplier about the oil.

Worked example: is raising the load a fix?

The tempting fix is to push the new lot a little harder. The page states 6–10% for soy, so moving from 8% to 9% stays inside that range. What would it cost, and is it really a fix?

At 200 candles a month, the extra 2 g per candle is 400 g of oil, or 400 ÷ 1,000 × ₹3,738.00 = ₹1,495.20 a month. That is a real cost — but the bigger problem is not the money. A 9% candle is a different candle from your approved 8% one. It needs its own wick check, because more oil can change flame and carbon build-up, and its own surface check, because more oil means more to hold. And it only makes sense if every future lot also needs 9%; if the next delivery matches the old lot again, you would be over-loading it.

So raising the load is a reformulation decision, not a goods-in fix. It belongs after a supplier conversation, not instead of one.

Approve, restrict or hold

Whichever way it goes, record the invoice number and date received — CSI product pages do not publish lot numbers — keep a small retained sample of the new lot, and resist the temptation to blend it into your old stock to average out the throw. That would hide the difference in every candle rather than solve it in any of them.

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