My Candle Burns Perfectly in a Narrow Jar but Tunnels in My Wider Jar Using the Same Wick — What Should I Change First?

Why the narrow jar points at the wick

Tunnelling has several possible causes: a wick too small for the diameter, a first burn stopped too early, a load or oil that asks more of the wick, an under-cured candle, a draught, a wick off-centre. Many makers who see a tunnel start guessing among them. You do not have to, because your narrow jar rules most of them out. Same wax, same oil, same load, same cure, same wick, burned the same way: perfect pool. Change only the jar, and it tunnels. What changed is the distance from the wick to the glass.

Worked example: a 7 cm inside jar has 3.5 cm from wick to glass and 38.48 cm² of pool; a 9 cm inside jar has 4.5 cm and 63.62 cm², 65.3% more. After four hours the wick has melted a pool 7.2 cm across in the wide jar: 40.72 cm², slightly more than it melted in the narrow jar, but only 64% of this jar's surface. The wick is doing roughly what it did before; the jar is asking for more. To reach the glass the pool must grow from 3.6 cm to 4.5 cm radius, 25% further. Why wider jars need more wick at all is in the tall-narrow vs short-wide post; how a same-capacity jar can differ this much is in the same-capacity post.

Measure the ring before you fix it

After a fair first burn, lay a ruler across the wide jar and measure the pool diameter, then the inside diameter. The width of the solid ring on each side is half the difference. Write both numbers down: they tell you how big a step the fix has to make, and whether the fix worked. A ring of a couple of millimetres is a different problem from one of a centimetre. As a guide (our judgement, not a rule), a pool that reaches only about three-quarters of the inside diameter after four hours, like the example's 7.2 of 9 cm, is a big enough gap that we would test Fix 2 alongside Fix 1 rather than after it.

Before any fix: was the wide jar's first burn fair?

A wide jar is less forgiving of a short first burn than a narrow one: the pool needs longer to reach the glass, so a burn stopped at the point that was plenty for the narrow jar can leave a ring the wide jar will then follow (the memory ring, Fix 3). Before you change the wick, check the comparison was fair:

If all six are "yes" and the wide jar still leaves a ring, the wick is the cause. If the first burn was short, relight it and let it run until the pool reaches the glass, attended, and watch whether the ring closes: that single re-burn tells you whether you had a wick problem or a first-burn problem.

Fix 1: one wick size up

Move one rung up in the wide jar only, and keep the narrow jar on its proven wick. With CSI's range the ladder runs Eco C1, Eco C2, then Cotton Braided Ready Made, whose page positions it for candles "exceeding 8 cm". So C1 goes to C2 (+₹3.54 a candle) and C2 goes to Cotton Braided (+₹2.56). How far to step and how to bracket when only the width changed is covered in the wider-jar step-up post; for a full three-rung bracket, see the three-wick bracket post.

What Fix 1 success looks like

Full pool to the glass all round in about 3 to 4 hours, about 0.5 to 1 cm deep (rules of thumb), steady flame, no soot on the glass, and the same behaviour in later burns and the final third. If the ring closes but the flame is tall or smokes, the bigger single wick has reached its limit in this jar: that is the signal for Fix 2, and the soot-versus-doubles trade-off in larger jars is examined in the sooting single-wick post.

Fix 2: a double wick

A double wick puts two flames on one diameter, each closer to the glass on its side. It is the right next step when Fix 1 still leaves a ring, or closes the ring only with a flame that is tall, flickering or sooting. With CSI wicks the obvious doubles are two C1s (₹11.80 a candle, ₹2.36 more than a single C2) and two C2s (₹18.88, ₹9.44 more). Two C1s is the gentler starting point; two C2s only if two C1s fall short.

What changes with two wicks

Two flames heat the glass beside each wick more than one centred flame does, and the two walls at right angles to the wick line are the furthest from both wicks and melt last. So a double-wick test watches both: do the cross walls reach full pool in about 3 to 4 hours, and does the glass beside each wick stay manageable, especially in the final third? Spacing matters and we publish no rule for it: mark your spacing on a template, record it, and keep it identical across test jars. The 4-inch decision between one and two wicks is worked through in the 4-inch luxury jar post; why doubles can run hot near the end is in the double-wick heat post.

Fix 3: first-burn habits and the memory ring

Soy and many container waxes tend to "remember" their first pool: if the first burn stops before the pool reaches the glass, later burns tend to stay inside that ring and dig down, a common pattern known as a memory ring. A wide jar is more exposed to it than a narrow one, because its first pool takes longer. Fix 3 is not a wick change; it is about how the candle is burned.

For customers: say it on the jar

In our judgement, the instruction most likely to prevent customer tunnelling is to let the first burn continue until the pool reaches the edge, commonly about 3 to 4 hours for a jar of this size, and not to leave a candle burning unattended. A care sticker costs ₹0.83 a candle from CSI's 500-roll (₹413.00) or ₹0.70 from the 1000-roll (₹699.00); the page does not show the printed wording, so ask us whether it covers first-burn advice, or add the line to your own label.

For stock already poured on the old wick

If a batch of wide candles has already been poured with the narrow jar's wick, Fix 3 is also the rescue for mild cases: a long, attended re-burn until the pool reaches the glass can level a shallow ring. A common method is a collar of aluminium foil folded over the rim with an opening over the pool, so heat reflects back onto the ring; stay with the candle throughout, keep the foil clear of the flame, and stop if the flame grows or the glass reads markedly hotter (check with a non-contact thermometer (CSI does not sell one), never your hand). It will not rescue a candle whose wick is simply too small: the tunnel comes back. For a whole batch, melting out and re-pouring with the fixed wick is often cleaner than rescuing jar by jar.

Testing the fixes without losing a month

The order of the fixes is the order you adopt them, not necessarily the order you test them. When the ring is large, as in the worked example, test Fixes 1 and 2 side by side: three jars one size up, three jars double-wicked, one narrow jar on the old wick as a control. Worked example: a wide jar holding a 300 g candle at 8% (24 g oil + 276 g wax), CSI 464 and Roasted Coffee. Weigh your own fill first.

What to buy for each fix

Five items, one per job, chosen on page wording, price and stock on 26 September 2026. CSI has no burn data for any jar-and-wick pairing, which is why each fix is a test before it is an order.

Cost per fix, per candle and per 100

Worked example, one 300 g wide-jar candle at 8%: 276 g of CSI 464 at the 10 kg price, 24 g of Roasted Coffee at the 1 kg price and a C2 wick come to ₹239.19 before the jar, labour, freight, packaging and GST. A double C1 is 4.9% of that. The fix is never the expensive part; the candles poured before the fix are. A hundred wide candles on the narrow jar's wick put ₹23,919.44 of materials at risk, and a tunnelled candle is the one a customer remembers.

The fix test

Frequently asked questions