If I Change Only the Wick, Do I Need to Repeat Long-Term Storage Testing or Mainly Combustion Testing?

A candle's life, phase by phase

The title asks a sharp question and deserves a sharp answer: after a wick-only change, you repeat combustion testing in full and you do not repeat long-term storage testing — with two small confirmation checks that stop the shortcut from biting. The reason is the physics of when the wick does anything. Until the candle is lit, the wick is a passive object held in solid wax. What happens on the shelf — sweating, frosting, colour change, cold throw — is decided by the wax and the fragrance oil and how they hold together. Once the candle is lit, the wick becomes the engine: it decides how much fuel is drawn, how big the flame is, how wide and deep the pool gets and how hot the jar runs.

Three phases are before the first light and five are after. The pattern in the Word column is the answer to the title. The unlit phases are KEEP, with two narrow CONFIRM checks. The lit phases are REPEAT without exception, including one that makers often file under storage: the surface the wax re-sets into between burns. That surface is shaped by the pool the new wick made, so it is a burn result. Likewise, if your original validation included lighting a candle that had been stored for a while, that aged-burn result is combustion and is repeated.

Why storage results survive

Storage testing exists to catch problems that develop in an unlit candle over days and weeks: oil droplets on the surface (sweating), white crystalline bloom (frosting), colour drift, and cold throw fading or changing. All of these are commonly described as consequences of how the wax crystallises and how well it holds the fragrance oil. The wick is not part of that chemistry in any meaningful way when it is cold. Your old storage results were produced by the same wax, the same oil at the same load, in the same jar — all of which are unchanged. So they remain valid. Repeating them would cost you weeks of shelf time and tell you nothing new.

This is the part of the title where the honest answer saves real time. A storage test that runs to your longest shelf period can take longer than the whole combustion test. If a wick change forced you to rerun storage every time, you would either stop improving wicks or start skipping tests. Neither is good change control. The change-control hub scores this change as a combustion change, and the matrix below is the reason.

The two CONFIRM checks you still owe

Two things about a new wick can show up on the shelf, and neither needs a full storage test. The first is mechanical: does the new wick stay upright and centred while the wax sets, and does its tab stay stuck to the jar base through storage? A different wick can be stiffer or softer, can have a different tab, and can sit differently in a setting candle. CSI does not publish construction details — priming or pre-waxing, core, tab height or tab type — for Eco, Cotton Braided or Wooden wicks, so you inspect it rather than assume. Use the same adhesive you use in production; changing the adhesive at the same time would be a second change, which is the subject of the lifting-tabs post.

The second is local: is there any visible change in the wax immediately around the new wick after setting and after storage — a ring, a discoloured patch, a hollow? A cold wick is not commonly described as changing the wax chemistry, but a one-candle look costs nothing and settles it for your materials. Both checks come from one new-wick candle and one control, kept unlit to the 14-day checkpoint (a labelled example) and then lit for an aged-burn check.

The combustion REPEAT, in full

On the burning side there is no partial answer. Every line is repeated against a control candle made with the old wick: time to full melt pool, pool depth, tunnelling, flame height, mushrooming, soot, jar heat, consumption rate, hot throw, the re-set surface and end-of-life behaviour. The set is three new-wick candles and three controls — a working practice, not a standard — and all six go to the end of usable wax. That last point is not optional for a wick change. A wick that looks right on the first burn can drift as the pool deepens; the one-size-down post explains why, and the tab-height post covers how a different tab can change how much wax is left at the end.

Consumption is the cleanest number on the sheet. If the new wick burns 3.4 g an hour where the control burns 2.8 g in the same cycle, it is drawing more fuel — and that usually shows on the flame and heat lines too. Compare cycle by cycle rather than averaging the whole burn, because a wick's behaviour can shift as the pool deepens. The wick-retest checklist post lists every combustion line in more depth.

The priced kit and the per-candle change

The worked example is one SKU: a candle in CSI's Yankee Glass Jar 130 ml with clear cap, poured in Natural Soy Pearl Wax with Lemongrass and Lime Fragrance Oil at 8%, currently on an Eco Thin C1 wick and moving to Cotton Braided. "130 ml" is the jar's brim volume, not a fill weight, and CSI does not publish one — so this page uses an illustrative 110 g fill (8.8 g oil, 101.2 g wax) that you replace with your own weighed pour. The wax, oil and control wicks come from your stock: 809.6 g of wax (about ₹364.32 at ₹450.00/kg) and 70.4 g of oil (about ₹415.36 at the 100 g rate).

₹497.60 buys the whole wick retest for one SKU. The jars are most of it; the new wick is ₹120.00 for ten, which leaves 6 spare for a re-pour. Now the per-candle side, which is often why the change is being made in the first place. Cotton Braided Wicks are ₹12.00 each at every pack size; Eco Thin C1 is ₹5.90. So this change adds ₹6.10 per candle: the illustrative 110 g candle goes from ₹144.40 to ₹150.50 in materials (wax at ₹450.00/kg, oil at its 1 kg rate, jar ₹47.20), before labour, packaging, freight and GST. If the new wick is being chosen for a reason — look, a burn problem, availability — that is fine; if it is being chosen for price, it moves the wrong way on CSI's list. The ₹2-per-candle post shows how to weigh a wick saving against its retest.

Decision rule and release

CSI publishes no numeric flame-height or jar-temperature limit. Acceptance means no worse than the approved control on every safety line, within your jar supplier's guidance and the recognised candle fire-safety standard you work to; ASTM F2417 is a commonly cited US standard, and this page quotes no numbers from it.

If one wick serves several SKUs — several fragrances in the same jar, or the same wick in two jars — the combustion set is repeated per jar size, and per fragrance where your records show fragrances burning differently. The eight-fragrance wick post covers that, and the lavender-versus-vanilla post explains why one fragrance passing does not clear another. The storage CONFIRM, by contrast, is done once per wick-and-jar pair: it is about the wick sitting in wax, not about the scent.

For the other single-component changes, the pattern flips. A wax change voids storage results as well as burn results, because the wax is the storage chemistry. A fragrance change does the same for the oil's half of it. A jar change keeps storage chemistry but reopens heat and geometry. Only the wick is almost purely a combustion change — which is why this is the one component where "mainly combustion testing" is the right answer.

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