My 8.5 cm Jar Needs a Very Large Single Wick to Reach the Edges but That Wick Produces Soot — Would Two Smaller Wicks Create a More Controlled Melt Pool?

First, make sure the soot belongs to the wick

Soot is incomplete burning at the flame: more fuel arriving than the flame can burn cleanly. A wick that is too big for its candle is one common cause. Others are just as common, and cheaper to fix: a wick left long between burns, a flame flickering in a draught from a ceiling fan, an AC vent or an open window, and a carbon cap left on the wick from the last session. Heavy fragrance loads are commonly linked to soot as well. Before you pour six candles to compare configurations, take one more session on the candle you already have.

Where soot lands on the glass, and at what depth it starts, can tell you more about its cause; that reading is the soot-band post. Why a big single flame tends to soot where two small ones don't is the 9 cm coffee post, which owns the mechanism. This page owns the comparison.

Setting up the head-to-head

The jar. CSI lists no 8.5 cm jar, so this is yours; measure the inside at the wax surface, mid-height and near the base. On an assumed 0.35 cm wall, 8.5 cm outside is 7.8 cm inside, a 47.78 cm² pool. How to measure it, and why the outside figure misleads, are in the 8.5–9 cm hub.

The fill and oil. Our worked example pours 250 g at 8% of total weight: 20 g of Dark Vanilla + 230 g of CSI 464. The Dark Vanilla page states "candles (6-10%)"; CSI 464's page states "Fragrance Load Up to 10%", so 8% is inside both ceilings. Weigh your own fill line if it differs; keep it identical across all six.

Arm A, the big single. One Cotton Braided, centred. If the big single you have now is another supplier's wick, use that instead; the point is to test the configuration that soots.

Arm B, the pair. Two Eco C1 on a diameter, 3.9 cm (39 mm) apart, which puts each wick 1.95 cm from the wall along their line. That spacing, equal to the inside radius, is a labelled starting point for testing, not an answer; the 9 cm placement drawing is post 4252. Stick the tabs on marks made from a paper template, and hold the wicks upright while the wax sets.

From nothing the cash outlay is ₹2,455.40. The 30 g of Dark Vanilla left over is enough for 2 retest candles at 6% (15 g each), the page's lower figure, if the load turns out to be part of the soot story. Costs are worked examples and exclude labour, freight, packaging and GST.

Three things to log, the same way every session

Soot grade, 0 to 3

After each session, when the flame is out and the jar has cooled, photograph the inside of the glass above the pool with a white card behind it, and grade it. The scale is ours, chosen because two people can agree on it from a photo: 0, clean glass, no smoke seen during the session; 1, a faint grey haze, no smoke trail seen; 2, a visible dark band on the glass or an occasional smoke trail from the flame tip; 3, a heavy black band, smoke in still air, or carbon falling into the pool. Note any carbon cap on the wick at 2 and 3 hours with its rough size. The white-cloth wipe card is post 4255's method; either works, but pick one and keep it.

Edge reach, in millimetres

At the end of each burn, photograph from directly above with a ruler across the rim and read the ring of solid wax at N, E, S and W. For the pair, put N and S on the wick line and E and W at right angles to it, because the pair's weak point, if it has one, is E and W. "0" means the pool meets the glass.

Trimmed flame height

At 1, 2 and 3 hours, hold a ruler behind the jar, not touching it, and read the flame from the wick tip to the top of the visible flame. For the pair, log both flames. Many makers use about 2.5–5 cm as a practical range; that is a rule of thumb, not CSI data. Log pool depth at the centre with a skewer at the end of each burn.

In this worked example the single wins the race to the glass by a burn and loses everything else: a flame above the practical range, a pool past 1 cm, a cap, and a soot band. The pair starts behind at E and W, exactly where the geometry says it will, and closes by burn 3 with small, clean flames. That is the result the question hopes for. Yours may not be: some pairs never close E and W, and some big singles burn clean once trimmed and moved out of a draught.

Reading the head-to-head

Read after burn 3, per arm, using the worst of the three candles. Our rule, labelled as judgement: an arm passes burn 3 when every candle shows soot grade 0–1, a trimmed flame inside about 2.5–5 cm, a centre no deeper than about 1 cm, and a ring of 0–1 mm all round. An arm with grade 2 or 3 in any candle fails, however well it reaches the glass.

Two notes on the second row, the one that trips people up. A clean pair that leaves wax at E and W is tempting to "fix" by going back to the big single, because the single reached the glass. Don't: you would be trading a cosmetic ring for a soot problem that customers see on their walls and lids. Step the pair up to 2 × C2, or look at its spacing. And if 2 × C2 soots too, CSI lists no sized, tabbed wick between C1 and C2. At that point the honest options are a spacing change, a lower load within the page's range, or another supplier's in-between size; ask us and we will tell you plainly what we don't have.

When it isn't the wick at all, the comparison still paid for itself: you know that at this load, in this wax, Dark Vanilla soots on anything, and that is a formulation question. The general trade-offs of one huge wick against two smaller ones, in any large jar, are covered in the huge-single-wick-soot post; this page stays with the 8.5 cm run.

₹ per candle: what the wick bill does and doesn't decide

Per 250 g candle, excluding the jar: ₹160.00 of Dark Vanilla (at the ₹8.00/g average of the bottles bought), ₹116.70 of CSI 464, and the wick. That gives ₹288.70 on one Cotton Braided and ₹288.50 on two C1. If the pair has to go up to 2 × C2 in round 2, its candle costs ₹295.58, and the pair then costs ₹6.88 more than the single in wicks.

The pair of C1s saves ₹200.00 per 1,000 candles in wicks: real, and small next to the oil. At the 500 g price of Dark Vanilla, 1,000 candles at 20 g each is ₹153,600.00 of oil (a worked example). What the wick bill leaves out is the time to fix two wicks, align them on a holder, check the spacing after pouring, and trim two wicks for the customer. That is where a pair can lose, and weighing it properly against soot and edge results is the scorecard post.

Holders are the other line the wick bill hides: each paired candle needs its wicks held upright while it sets, which means a Steel Wick Holder (₹50.00 each, reusable) or two marked sticks per jar. For a six-candle test that is trivial; for a 200-candle pour it is a count of holders and a bench layout, covered in the split production plan.

What to buy, and what to skip

Six items in the order the head-to-head needs them, chosen on page statements, price and stock on 29 September 2026. CSI publishes no wick-performance data, so nothing is ranked on burn results. Oil candle counts use the 250 g worked-example fill (20 g each) and the standard 150 g candle (12 g each).

Frequently asked questions