My 8 cm Jar Has a Full Melt Pool in 45 Minutes — Is That Evidence the Wick Is Too Large Even if the Candle Does Not Visibly Soot?

Why 45 minutes is a question, not a verdict

The size of a melt pool depends on how much heat reaches the wax edge and how much heat the wax needs to melt. The wick sets the first. The second is set by the room, the air around the jar, and how warm the whole candle already was when you lit it. Change the second and the same wick can reach the glass in a third of the time. That is why "45 minutes" on its own cannot separate "wick too big" from "candle already warm".

It is still a real warning sign. A pool that is full in under an hour commonly comes from a flame putting out more heat than the jar needs. Over a whole candle that surplus tends to show up as a pool deeper than about 1 cm, a flame that grows as the wax level falls, carbon on the wick, and glass that runs hot in the final third. The absence of soot does not clear the wick. Soot tends to arrive late in a session and late in a candle's life, which is why soot that starts only after the first ten hours is its own diagnosis.

So the question has two halves. First, was the 45 minutes produced by the wick or by the conditions? Second, if it was the wick, does the smaller wick still reach the glass? The combined over-wick scorecard (pool time, trimmed flame height, mushrooming and soot together) belongs to the 6 cm fast-pool, big-flame post,. This page is about the case where speed is the only symptom.

What an 8 cm jar should take, on paper

First, which 8 cm? The title does not say inside or outside, and it matters. CSI lists no jar at 8 cm. Its nearest glass listings are at 7 cm (for example the Clear Glass Jar with Golden Lid (150 gram), which states an outer diameter of about 7 cm) and at 10 cm (the Apothecary Glass Candle Jar with Dome Lid). So your 8 cm jar is your own, and you should measure its inside at the rim, the middle and about 1 cm above the base. The method is in the external-versus-internal diameter post, and how far 5 mm moves the pool is in the 5 mm diameter post. We read "8 cm" as the outside and assume a 0.35 cm wall. That is our assumption; replace it with your measurement.

Whichever row fits, 45 minutes is about a quarter of the rule-of-thumb time. A thicker wall or a jar that narrows at the top leaves less surface to melt (8% less at a 0.5 cm wall), but neither turns three hours into 45 minutes. Something needs explaining: the conditions or the wick. The slow end of the same jar is the near-four-hours post.

Five things that speed a pool without a bigger wick

Each confounder does the same thing: it hands the flame a head start, so the pool reaches the glass sooner with no change in the wick. They are tendencies, not laws, and they add up. A second burn in a warm room with the fan on can look nothing like a first burn in still air. Rule them out on one fresh candle, all at once. Then the re-run means something.

The two that need numbers

The room. Read the room at the bench before you light, on the same thermometer every time. The Pen Thermometer's page, in the text we captured, gives no range or accuracy figure. Use it to compare today's room with last week's, and don't treat it as a calibrated instrument. Test at the room temperature your candles will actually be burned in. If that is a 31°C flat in May, the fast pool may be a fair picture of your customers' homes, and a wick that runs hot there is a problem worth finding now.

The relight. Wax temperature at relight is hard to measure cleanly, because a probe pushed into set wax reads the spot it touches. The practical measure is time: write down the hours since the flame went out. A candle relit after 90 minutes and one relit the next morning are different experiments, even on the same wick.

The short fill, in centimetres

Our worked example fills 200 g. Using the common water-weight rule of thumb (wax at roughly 0.86–0.9 of the water weight, confirm with a weighed pour), that is a wax column about 5.3–5.6 cm tall in a 7.3 cm-inside jar. Pour 150 g instead, 25% short, and the column is about 4.1 cm against about 5.4 cm, so the surface sits about 1.4 cm lower. If your fast candle was a leftover-wax pour, weigh it before trusting the timing.

The oil also changes pool speed. A light, fresh oil like our worked example's Blue Ocean commonly burns more easily than a dense gourmand or resin (a tendency). If your 45 minutes came right after a fragrance change, see the post where only the fragrance changed.

The 15-minute pool timeline

The timeline is a single first burn of a fresh candle, read every 15 minutes until the pool meets the glass all round. It does two jobs. It gives a clean time-to-full-pool, and its shape shows how the pool grew: a steady spread or a sprint.

In column B the cleared candle takes 135 minutes, 73% of the rule-of-thumb figure, and ends with a depth under 1 cm. The 45 minutes in column A was the relight, the room and the fan, not the wick. Column C is the other outcome: with everything cleared the pool still covers 65% of the surface at 30 minutes and meets the glass at 45. It is also deeper at 3 hours and the flame sits at the top of the practical range. No soot, but that is the pattern the step-down test exists for.

Reading the timeline: keep, watch or step down

Why under one hour, and not "under two"? The line is our judgement, and we chose it to be conservative. An hour is about a third of the rule-of-thumb time for 8 cm, and at that speed, in our judgement, a smaller wick is worth two candles to test. Between one and two hours, a light oil, a soft wax or a slightly narrow inside can plausibly explain the speed. Changing the wick there, on speed alone, risks swapping a fast-but-fine candle for a tunnelling one. That band gets watched, not changed. How depth behaves further down the jar is covered in the post on a pool that goes very deep near the bottom.

Still under an hour: one rung down, in twins

Hold everything but the wick: the same wax bag, Blue Ocean at 8% of total weight, jar batch, 200 g fill (16 g of oil + 184 g of wax), pour temperature, cure and room. Two cells of two candles: your current wick (the control) and one rung down. CSI's rungs are C1, C2 and Cotton Braided. There is no sized, tabbed wick between them, so "one rung down" is a real step, not a nudge. From Cotton Braided, that is C2. From C2, it is C1, and the C1 10-pack is out of stock on 29 September 2026, so buy the 20. If your current wick is from another supplier, keep it as the control and ask us where it sits. Stepping from C2 to C1 in a 7 cm jar is its own post (the 7 cm step-down pair). A double-wick candle that pools fast is a different problem too, covered in the 8.5 cm double-wick speed post and the 10 cm three-arm step-down.

Per candle, before the jar, that is ₹184.56 on Cotton Braided and ₹182.00 on C2: ₹79.20 of oil and ₹93.36 of wax, plus the wick. The C2 candle saves ₹2.56 in wick, ₹256.00 over 100 candles. That is a small saving, and it should not decide the test. From nothing, the cash outlay is ₹1,665.20 with the C2 20-pack and the thermometer, or ₹1,570.80 with the C2 10-pack. If you already own the wax, oil, jars and a thermometer, it is ₹214.40 for a 10-pack of each wick. Costs are worked examples and exclude jars, labour, freight, packaging and GST.

Protocol

Pour all four on one day. CSI 464's page states "Pour Temperature 80°C – 90°C"; if your jar's page states no heat rating, pour at the low end and pre-warm clean jars (our judgement). Cure them identically. Then give every candle the cleared conditions from the timeline: overnight cool, still air, the same room, trim to about 5–6 mm. Log the 15-minute timeline on burn 1, then pool, depth and flame at the end of each session of about 3 hours. Burn within sight. Carry both cells to about 1 cm left. Judge the glass by what you see (flame distance to the wall, soot on the rim), never by touching it. The pass line for "done" is in how far down to burn a test candle.

The third row is the honest limit of a speed-only complaint. If your current wick holds through the full life (depth under about 1 cm, calm flame, nothing alarming at the bottom) and the smaller wick cannot reach the glass, then the 45 minutes was fast but not a fault. Keep the wick. What decides the lower third is set out in why the flame turns aggressive near the bottom.

What to buy, and what to skip

Five items, in the order the test uses them, chosen on page statements, price and stock on 29 September 2026. CSI publishes no wick-performance data, so nothing here is ranked on burn results. Oil counts are at 16 g (a 200 g fill) and 12 g (a 150 g candle).

Frequently asked questions