My Candle Wick Works Perfectly With One Fragrance but Tunnels With Another — Do I Need Different Wicks for Every Scent?

Is it actually the fragrance? Four free checks

When a maker says "the wick is fine with lavender but tunnels with coffee", the two candles were rarely poured under identical conditions. Different days, different loads, different ages, sometimes different jar batches. Before a scent earns its own wick, it has to fail with everything else held equal. These four checks cost nothing if you own a scale.

Check 1 in numbers. Load is a percentage of total weight: 8% in a 150 g candle is 12 g of oil and 138 g of wax, 10% is 15 g and 135 g. If scent A went in at 8% and B at 10%, B has 3 g more oil in the same space, and the comparison is already unfair. Measure the inside diameter of both jars too: the Clear Glass Jar with Golden Lid (150 gram) page states an outer diameter of approx. 7 cm, and a different jar that looks similar may not be. Geometry is unforgiving: in a worked example, a 5 cm pool in a jar 6.5 cm across inside melts only 59% of the surface.

Check 2 in practice. A commonly cited rule of thumb is roughly one hour of burning per 2.5 cm of jar width for a full first pool, so a jar around 7 cm across needs about three hours; not CSI data, and your jar may differ. If scent B's first burn was a one-hour sniff test and A's was a proper evening burn, you are comparing burn habits, not scents.

Why one scent can need more wick than another

A wick draws melted wax and oil up by capillary action and burns it. Fragrance oils are not all alike: some are light and top-led, some are dense, sweet or resinous. Heavier or more viscous oils, commonly the dense gourmands (vanilla, caramel, chocolate, coffee), resins and some ouds, often need a wick adjustment compared with a light citrus or fresh scent in the same jar and wax. That is a tendency across the trade, not a law, and it does not show on a product page. CSI has no measured viscosity or burn data for its oils, so we will not tell you which of your scents will tunnel. We will tell you which ones to check first.

Load matters as much as family. A scent you run at 10% puts 3 g more oil into a 150 g candle than one at 8%, and more oil can change the wick's needs (the full load-and-wick grid is in Does Increasing Fragrance Load Mean I Need a Bigger Wick?; heavy oils specifically in Do Heavy Fragrance Oils Need a Larger Candle Wick?). This is why the bracket below includes a lower-load candle: sometimes the right fix for a tunnelling scent is two points less oil on the same wick, not a bigger wick. If the page's range allows it, that can also lower your cost per candle.

The bracket: six candles for one tunnelling scent

This is deeper than a single re-wick. It tests the wick size and the load separately, repeats the winner, and includes a control that proves your pour was normal. All candles are 150 g in your usual jar and wax, poured from one melt on the same day except the repeat. Tunnelling often shows over several burns rather than one, so each candle gets three burn sessions of up to four hours, pool width logged hourly.

Oil for scent B: 12 + 12 + 9 + up to 12 = 45 g at most, so a 50 g bottle covers the whole bracket with 5 g to spare. Wicks: four C1 and one C2, plus one of the winning size for candle 5, from one pack of each. Wax: up to 834 g (138 g per 8% candle, 141 g per 6% candle). If you own wax and jars, the new spend is ₹153.40; the materials consumed are worth up to ₹1,032.05 excluding both oils (wax ₹423.17, jars ₹566.40 valued at ₹94.40 each, wicks ₹42.48), before labour, freight, packaging and GST. Wash and reuse the jars.

Class X: what to do when neither wick works

Some scent-jar combinations fall between the two Eco sizes. You have four options, cheapest first. Lower the load within the oil page's range and rerun candle 4's comparison at a point you have not tried. Move the scent into a jar of a different width, which is a new bracket. Try a different wick family, such as Performance Wooden Wicks (₹59.00 each from the pack of 10), knowing that a family change is a whole new test, not a size step. Or retire the scent from that jar. What you should not do is ship it on the wick that almost works.

The SKU wick map: classes, not one wick per scent

Our judgement, from how ranges are usually built: most scents in a range share the base wick for a given jar, a minority need the next size, and a few do not fit at all. How many fall into each group depends on your jar, wax, loads and families, which is why you map rather than guess. The sibling post on whether different oils need different wick sizes covers the yes-sometimes answer; here is the working document.

Three rules that keep a wick map manageable

No more than two classes per jar. Our house rule of thumb, not a law. Two classes means two bins and one decision per batch. A third class usually means a scent belongs in a different jar or at a different load.

A class is earned, not inherited. A new scent starts as "unclassed" and cannot be poured for sale until a bracket gives it a class. Similar-sounding scents do not share a class by default; "vanilla" on two pages does not mean the same oil.

Every change reopens the line. A new jar, a new wax, a load change or a switch of wick family sends the SKU back to the bracket. Retest policy in detail is in Should I Retest My Wick Every Time I Change Candle Fragrance?.

Mapping a range: 6, 12 and 20 SKUs

For a whole range, every SKU gets a two-candle check at your house load (C1 and C2), and the ones that tunnel on C1 get the load candle and a repeat. How many need follow-up is unknown until you pour; the table assumes a third of SKUs as a worked example. Oil is your own: 24 g per SKU for the check, plus 21 g for each follow-up (9 g at 6% and a 12 g repeat), so a 50 g sample covers a scent even if it needs the full follow-up.

Look at the last row before you start. Forty-eight burn sessions for six SKUs is manageable; 156 for twenty is a part-time job. That is the honest argument for the calibration pair and the priority table: bracket the dense, high-load scents first, and give the light, top-led ones a single C1 check with a C2 only if they miss the glass. For how many combinations to test before a launch in general, see How Many Wax × Fragrance Combinations Should I Test Before Launching?.

Production control: the right wick in the right jar

For the bigger programme of standardising wax, wick classes, loads and bulk buying across 10 to 20 scents, see the capstone post on consistent hot throw across a range. For the business-wide testing SOP, How to Build a Fragrance Oil Testing SOP for a Candle Business.

What to buy

The bracket first, then the tool that removes a false cause, then two optional calibration oils, and one wick family for wider jars only. Oils are chosen for contrasting stated notes (top-led citrus against a dense gourmand base), stated load and cure, and full stock on 25 September 2026; not for throw, which CSI has not measured. Candle counts assume 150 g at 8%.

Frequently asked questions