Signs Your Candle Wick Is Too Small

An under-wicked candle makes too little heat for its jar. The signs are a melt pool that stops short of the edge, a ring of wax left against the glass, a flame that is small or goes out, and a weak scent. Before you blame the wick, make sure the candle burned long enough. Then go up one size in the same series and test again, in your own jar with your own wax. Never leave a test candle burning out of sight.

What are the signs?

• The pool never reaches the edge. CandleScience says an under-wicked candle "will not burn out to the edge of the container" and instead burns down the middle, or tunnels. Makesy says a wick that is too small "simply cannot generate enough heat to melt wax all the way to the edges," and calls it especially common in wider jars with a single wick.
• A ring of wax stays on the glass. Lone Star lists a ring of unmelted wax against the glass as the tunneling signature.
• The flame goes out or drowns. CandleScience says the flame will often "extinguish itself before all the wax is burned." Lone Star describes a small flame drowning in melted wax, and says to trim the wick, remove wax from the pool after the flame is out, and size up.
• The scent is weak. Lone Star ties a shallow pool to weak hot throw, because the pool is too shallow to release the fragrance.

How long should I wait before I decide?

Long enough to be fair. CandleScience's wicking guide says to burn 3 to 4 hours at one lighting before judging, since a shorter burn "might not allow time for the wax to melt." Its burn test page says to wait until the fourth burn cycle before being critical of the pool. Use both: 3 to 4 hours each lighting, and judge at the fourth cycle.

What do I do about it?

1. Trim the wick to 1/4 inch (6 mm) and check you have a flame about 1 inch (2.5 cm) tall, as CandleScience says.
2. Burn it long enough, as above.
3. If it still falls short, go up one size in the same series. CandleScience's example is moving from an LX 14 to an LX 16. Jumping to another series muddies the result.
4. Do not swap the wick mid-test. CandleScience says the result will not show how the candle really burns.
5. Change one thing at a time. Midwest Fragrance suggests trying a wick 1 to 2 sizes up for weak throw.

CandleScience also says a heavier fragrance or dye load can call for a bigger wick. Retest when either changes. To rescue a candle that already tunneled, see Why is my candle tunneling? For the opposite signs, see Signs your wick is too big.

Worked example: how much wax is still solid?

Say a jar is 3.5 inches (8.9 cm) across. You measure the pool at 1, 2 and 3 hours, the checkpoints Makesy uses. Share of the surface melted is (pool width / jar width) squared, because area goes with the square of the width. All measurements are examples.

At 3 hours, 59 percent of the surface is still solid, with a ring 0.63 inch (16 mm) wide on each side: (3.5 - 2.25) / 2 = 0.625. The pool grew 0.50 inch, then only 0.25. It is leveling off, and the CandleScience test of within 1/4 inch of the edge (a pool of at least 3.0 inches here) fails.

Now the next size up: 2.9 inches at hour 2, and 3.4 at hour 3. That is (3.4 / 3.5)^2 = 0.944, or 94 percent melted, with a gap of 0.05 inch on each side. It passes. You would still check flame height, jar heat and soot before you pick it.

Wick or burn habit? Check by cycle

A ring of wax on the glass can come from the wick or from short burns. Track the ring once per cycle, burning each cycle 3 to 4 hours as CandleScience says. All numbers are made-up examples, for a 3.5 inch (8.9 cm) jar. The ring is the width of wax left on the glass, measured at the widest spot.

Candle A still has a ring at cycle 4. CandleScience says a ring that is still there after the fourth burn cycle may mean you need to wick up, so go up one size in the same series and test again. Candle B's ring closed by cycle 3. Keep that size. If your ring will not shrink and some of your cycles were short, burn longer first, since a ring from short burns is a habit, not a wick.

Top of the series and still too small?

If the largest size in your series still falls short in your jar:

• Test a larger wick series, or use two wicks in a wide jar. Makesy says to consider both for vessels over 3.5 inches, and recommends double or triple wicks at 4 inches and up.
• Retest from scratch, one change at a time.

Common mistakes

• Judging after one short burn and calling the wick too small.
• Switching series and size together, then not knowing which change worked.
• Adding more fragrance oil to fix weak scent. Midwest says too much oil can clog the wick.
• Skipping the trim before each session.
• Not retesting when the wax batch, the oil or the dye changes.

Questions

Is tunneling always a wick that is too small?

No. The National Candle Association says a candle that does not melt edge to edge forms a "memory ring" and keeps tunneling, so a short first burn can cause it. Our tunneling guide covers both causes.

Can a wick be too small and the candle still burn fine at the start?

Yes. CandleScience notes that early cycles send most heat out the top, and the pool can improve as the wax level drops and the flame sits lower in the jar. That is why it says to wait for the fourth cycle.

Is a wick too small unsafe?

The heat warnings I read are about wicks that are too big, not too small. But a flame that flickers or goes out is something to watch, so stay in the room. See our guide on wicks that are too big.