I’m Using a 9 cm Jar with 10% Oud Fragrance — Should I Start Testing with One Large Wick or Two Smaller Wicks?

Why open with both builds

The usual advice is "start with a single and go double if it fails". That sounds economical, and at 6 or 7 cm it usually is. At 9 cm it is not, because the single and the pair are both genuine candidates, and each has a week of cure and three burns attached before you learn anything.

The second arm costs two candles, ₹569.40 of materials in the worked example. What it saves is time: if the single fails in round 1, the pair's result is already on the table, and round 2 can refine instead of restart. For anyone pouring oud for a season, the week matters more than the rupees.

The jar itself is your own; CSI lists no jar at 9 cm. Measured 9 cm across the outside, on an assumed 0.35 cm wall, it is 8.3 cm inside with a 54.11 cm² pool, 27.05 cm² per wick for a pair. Measure yours at three heights. The broader single-versus-double trade-off in large jars, before any oil is chosen, is single versus double wicks in a large jar; the diameter at which you should start comparing the two at all is the run-both zone.

10% oud: what "at the ceiling" means for the wick

Woody Oud's page states "candles (6-10%)". CSI 464's page states "Fragrance Load Up to 10%". By the two-ceilings rule the lower governs, and here they agree: 10% is the edge. Neither is a regulatory limit, and neither is a performance target; the most oil the wax is stated to hold is not the same as the load that burns best.

There is a wrinkle. CSI works loads as a percentage of total candle weight, and a 300 g candle at 10% is 30 g of oil and 270 g of wax. CSI 464's page does not say which basis its 10% uses. Read on wax weight, 10% of total is 11.11% of wax, past the ceiling; 10% of wax would be 9.09% of total. If you want a top load that satisfies both readings, 9% of total (9.89% of wax) does. The full conversion is in the load-basis post. None of this changes round 1, but it is why round 2's load check starts at 9%.

Why does the load matter to the wick? Heavy, resinous and woody oils are commonly linked to more carbon on the wick, sootier flames and slower reach to the glass, and the effect tends to grow with load. A wick that carbons at 10% might be fine at 8%. That is a tendency, not CSI data, and it is exactly what a round-1 result can hint at: if both builds carbon heavily, the common factor is the oil at its ceiling, not the wick count. The same confound in a smaller jar, where the oil and the load changed together, is untangled in the 7.5 cm oud confound.

Round 1: four candles, four gates

The flame gate uses the ruler method from the 9 cm flame-height protocol. Carbon is the gate to watch most closely: heavy oils at high load are commonly linked to carbon that builds over a session and over several burns, which is why burn 3 counts, not burn 1. Carbon that appears only after many cycles is its own diagnostic, mushrooming that appears only after several burn cycles.

What winning means. A build wins round 1 when both its candles pass all four gates. If both builds win, the single takes the tie: one wick to set, trim and explain on the label, and nothing to space. If one candle of a build passes and the other doesn't, that build has not won; check the wick positions before you read anything into it. And a win is a candidate, not an approval. Heavy oils and pairs both commonly change character in the lower half of a jar, so the winner goes on to about 1 cm left before production.

Round 2: the move each result points to

Outcome 1, both pass. The single is enough. Two more singles confirm it isn't a lucky pair of candles; then all the singles run to full life. Keep the pair's burn-3 records: if the single fails late, the pair is your round-3 fallback with a head start.

Outcome 2, only the pair passes. 10% oud at 9 cm wants two flames. Confirm with two more pairs and run the full life. Watch the lower half closely: two flames add heat to the glass as the jar empties, so judge by observation and with a non-contact thermometer if you own one (CSI does not list one), never by touch.

Outcome 3, a split verdict. The single carbons or soots, too much wick for this oil, while the C1 pair is clean but short at the edge, too little. The answer lies between them on the pair side. Round 2 tests the two ways to give the pair more reach: a C2 pair at the same 4.0 cm (₹18.88 a candle in wicks), and the C1 pair moved out to 4.5 cm, 1.9 cm from the glass along the line. Which of those reaches the glass cleanly is your build. If that sounds like the spacing-versus-size question, it is; the full 2×2 is the spacing × size test.

Outcome 4, carbon on both. Both builds grow carbon caps (grade 2 or worse) at 10%. The wick count is probably not the problem. Take the better build and pour two at 9% (27 g of oil in 300 g) and two at 8% (24 g). If carbon clears at 9%, you also land on the load that satisfies both readings of CSI 464's ceiling. Dropping from 10% to 9% saves ₹13.59 of oil per candle; to 8%, ₹27.18. Argued against our own interest: if 8% is where the carbon clears, 10% was costing you oil and burn quality at once, and the right purchase is less oud, not more wick.

Grams, wicks and rupees for both rounds

Round 1 consumes 120 g of Woody Oud (₹543.60), 1,080 g of CSI 464 (₹547.99) and six wicks (₹47.60): ₹1,139.19, your jars not included. From nothing, round 1 costs ₹1,729.92: Woody Oud 100 g and 50 g (₹724.52, leaving 30 g, one more candle), CSI 464 1 kg and 500 g (₹767.40), a Cotton Braided 10 and a C1 20. If you already own the oil and wax, the wicks are ₹238.00.

Per candle at 10%, oil, wax and wick only: ₹284.90 on one Cotton Braided, ₹284.70 on a C1 pair, ₹291.78 on a C2 pair. The wick build moves the cost by paise; the load moves it by rupees (₹135.90 of oil per candle at 10%, ₹122.31 at 9%). All figures exclude labour, freight, packaging and GST.

Buying for both rounds. Round 2 adds 60 g to 120 g of oil, depending on the outcome. Three 100 g bottles (₹1,359.36) cover round 1 and any four-candle round 2 at 10%. The 500 g (₹2,265.60) covers both and a full-life pair, with more left. Per gram they are identical; choose by whether oud is going into production.

What to buy, and what to skip

Skip: a second oud "to compare" in round 1. White Royal Oud (₹810.00 for 100 g) and Dark Vanilla Oud (₹590.00 for 100 g) are different oils with their own pages; adding one turns a wick test into an oil test. Skip Eco C2 until round 1 lands on outcome 3. And skip a bigger pack of anything until a build has passed its full life: every wick here is flat per wick at every pack size.

Frequently asked questions