If I Change Only the Jar, Which Tests Should Be Repeated to Confirm Wick Performance and Container Heat Remain Acceptable?

Measure first: the jar comparison sheet

When only the jar changes, the wax, the fragrance oil and the wick are the same, and so is their chemistry. What changes is the space the candle burns in: how wide the pool can spread, how deep the wax sits, how the glass sheds heat, what the base does at the end. The fastest way to decide how much retesting you need is to measure both jars side by side before a test candle is poured. CSI does not publish internal diameters, glass or base thickness, heights or taper for its jars — only two fills are published (the Golden Aluminium Tin at 85 g and the Heart Cutout Velvet Jar at 50 g wax capacity) — so these are your measurements.

Three of the nine measurements matter most for the title's two concerns. Diameter at the fill line governs whether your wick can still bring the pool to the edge. Wall and base thickness and glass finish govern how the jar handles heat. The rest tell you whether this is still the same product — if the new jar cannot hold your label weight at a sensible fill line, you are not changing a jar, you are launching a new SKU, and the same-200-g, wider-and-shorter post walks through that trade-off.

Geometry: why small diameter changes are not small

The wick has one job in a container: melt the wax out to the glass within a burn cycle without overheating anything. The area it must melt is the circle at the wax surface, π × d² ÷ 4, so it grows with the square of the diameter. Using illustrative numbers — not the dimensions of any CSI jar — a move from a 7.0 cm to a 7.5 cm internal diameter is 7.1% wider but gives 14.8% more pool area (38.48 cm² to 44.18 cm²). And if the candle weight stays the same, the wax column gets 12.9% shorter, because the same volume is spread over the larger area. The same maths runs in reverse for a narrower jar.

Two things follow. First, even the smallest change in that table — 7.0 to 7.2 cm, 5.8% more area — is enough that you cannot assume the old wick still reaches the edge; the 7.6-to-7.9 cm post works a real-world-sized example of the same question. Second, the column-height change moves where end-of-life falls and how many burn cycles the candle has. Neither is a reason to panic; both are reasons to burn test. What geometry cannot tell you is the answer — CSI publishes no wick-size chart per diameter, and none would be reliable across waxes and oils anyway.

The retest matrix for a jar-only change

With the measurements in hand, sort your test file. The jar is not part of the wax–oil chemistry, so the storage chemistry lines stay. It is very much part of how the candle burns, looks and is packed, so those lines are repeated, and a jar brings some genuinely new questions — appearance through different glass, label and lid fit.

The title asks specifically which tests confirm that wick performance and container heat remain acceptable. In the matrix, those are the REPEAT lines from time to full pool down to end-of-life: pool reach and time, depth and tunnelling, flame, mushrooming and soot, jar-side heat through the burn, hot throw, consumption, and end-of-life heat with wax left behind. They come from one burn set. The storage-side lines are handled by a single pair of unlit candles.

The test: one burn set, one appearance pair

Heat is recorded at the same three heights on every jar, every cycle, so that a hotter lower third on the candidate shows up clearly. If you use a surface thermometer, write the reading; if not, a consistent touch check at the end of each cycle (back of the fingers, same spot) is still useful as a comparison, never as an absolute. CSI publishes no numeric jar-temperature or flame-height limit. Acceptance is no worse than the current approved jar on every safety line, within the new jar supplier's guidance and the recognised fire-safety standard you work to (ASTM F2417 is commonly cited). A frosted or matte finish changes how heat feels in the hand and how the candle looks — the frosted-glass post covers that specifically.

The priced kit, and whether the change pays

The worked example is a candle currently in a White Matte Glass Jar being moved to CSI's 200 ml Salsa Glass Jar with golden lug cap, poured in Luxury Soy Wax CSI 464 with Fresh Strawberries Fragrance Oil at 8%. Neither jar's fill weight is published; this page uses an illustrative 170 g fill in the Salsa jar (13.6 g oil, 156.4 g wax) — weigh your own, because the candle you sell has to match its label. Wax, oil, wick and the control jars come from your stock: the new-jar candles need 625.6 g of wax and 54.4 g of oil.

Stage 1 is ₹755.20, or ₹401.20 if you already own a 1 g scale. Now the question most jar changes are really about: does it pay? The White Matte jar is ₹70.80 each (₹354.00 for 5). The Salsa jar is ₹40.12 each in a 5-pack, ₹29.50 in a 50-pack and ₹29.50 in a 100-pack. So the jar saving is ₹30.68 per candle at the smallest pack and ₹41.30 at 100. Add an example ₹1,500.00 for your own time on the test (replace it with your figure) and the one-off revalidation is ₹2,255.20. Payback is revalidation ÷ saving: 74 candles at the 5-pack price, 55 at the 100-pack. Those numbers only hold if the smaller illustrative fill is acceptable to your customers — a 170 g candle is not a 200 g candle, and pricing it as one would be dishonest.

Decision and release

Record the jar on the specification by its measurements, not just its name. Two jars sold under the same name by different suppliers — or even the same supplier across moulds — can differ, and the comparison sheet is what lets a future reorder be checked in two minutes. Keep one empty jar from the approved order as a physical reference beside the retained candle. The 1,000-candle jar post shows how to use those reference measurements when a substitution is forced at short notice, and the out-of-stock jar post covers choosing the alternative that needs the least redevelopment.

For the other single-component changes, compare how different the pattern is. A wax change voids storage chemistry and burn results together. A fragrance change keeps jar and wax data but repeats every candle result. A wick change keeps storage and repeats combustion. A jar change keeps storage chemistry, repeats combustion and heat, and adds packaging questions no other change asks. Knowing which pattern you are in is most of change control.

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