Should Container Shape Be Included in Wax Qualification Rather than Assuming All 200 g Jars Behave Similarly?

Yes — shape belongs in qualification. But not every shape needs every test.

Wax qualification usually means pouring the candidate waxes in one jar, scoring them, and rolling the winner out across the range. That works for hot throw and cost, which depend mainly on the wax, the oil and the load. Glass adhesion is different: it is commonly described as depending on the glass face the wax sets against — how much glass each gram of wax meets, how deep the wax sits, which way the walls lean, how heavy the glass is and how the jar cools. The same-capacity, different-shape post shows with geometry how far those can differ between jars that hold the same candle. So a wax that passes in your 150 g tumbler has passed in your 150 g tumbler. Whether it passes in your shouldered jar and your large jar is a separate question, and it is cheaper to answer it before the switch than after a production run.

The single cheapest first step costs nothing: look at your own records. Which of your current jars already shows the most wet spots with your current wax? If you have zone maps or even phone photos from past batches, rank your jars from most to least troublesome. That ranking tells you where a candidate wax is most likely to fail, and it decides the test design below. If you have no records, pour one batch of your current wax into three of each jar this week, photograph them at 48 hours and 7 days, and rank them — that is the cheapest qualification work you will ever do.

The worked example on this page is a maker selling one fragrance — Fresh Strawberries at 8% — in three clear CSI jars: the Clear Glass Jar with Golden Lid (150 gram) (page fill about 150 g), the 200 ml Salsa Glass Jar (filled to an illustrative weighed 170 g; its fill is not published) and the Borosilicate Glass Jar 600 gram (page: "ideal for 500–600 g wax fill"; 600 g used here). The maker's current wax is the control in every arm, and two CSI candidates are tested: Luxury Soy Wax Chunks and Premium Coconut Soy Wax CSI 468. Both pages claim excellent glass adhesion, as does the CSI 464 page — the same claim on all three, so it ranks nothing. Only the test in your jars decides.

Three ways to design the qualification, priced

Every design below uses three numbered jars per arm (a labelled working practice for a screen), the same oil bottle at 8%, the same wick from one pack, the same cleaning routine and each wax poured inside its own page's temperature figure. What changes is which jars each wax meets. Prices are listed in-stock CSI packs; jars you already hold can be struck off, which most makers selling these jars will do.

Design C saves ₹2,866.92 against the full matrix in this example, almost all of it in Borosilicate jars and the wax and oil that fill them: one three-jar arm in the 600 g jar costs about ₹2,153.39 with Chunks, against ₹684.82 in the Clear 150 g jar and ₹573.17 in the Salsa jar. What it gives up is small and acceptable for most makers: it will not tell you that the losing candidate would have been fine in the easy jars. You are choosing one wax for the line, so that answer has little value.

Design A is the one most makers run by default, and it is the one this page argues against for adhesion. It is fine as a first screen if the jar it uses is your hardest jar — at that point it becomes stage 1 of design C. It is risky when it uses your easiest jar, because a pass there says almost nothing about the others.

Shape families: when two jars can share a result

A range with many SKUs can still be qualified at sensible cost if jars are grouped into families that are likely to behave alike, and one jar per family — the hardest — carries the test. Grouping is your judgement, written down; it is not a rule from CSI or an industry standard. The useful criteria are the ones you can measure on your bench: the internal diameter at base and mouth, the wax depth at your fill line, whether the wall is straight, flared or shouldered, and the weight of the empty glass per gram of candle. Jars from different suppliers or different moulds belong in different families even when their dimensions match, because glass from one supplier can behave differently from another's.

Notice how much the illustrative glass-per-gram figure moves: 0.70 g in the large jar against 1.73 g in the 150 g jar. A large jar puts much less glass around each gram of wax, and much more wax between the centre and the wall — two reasons, commonly described, why a big jar can behave differently from a small one in the same wax. These weights are examples only; CSI does not publish empty-jar weights or glass thickness for any jar. Weigh five of each of your own.

Design C, step by step

Clean every jar the same way before every round — a wipe with Isopropyl Alcohol Spray and a lint-free cloth, then dry completely; isopropyl alcohol is flammable, so keep it away from flame and the melter. Pour each wax inside its own page figure: Chunks' spec table gives 75–80°C (its step list shows 70–80°C), CSI 468's page gives 58–60°C, and the Clear 150 g jar's page states hot pour up to 85°C. The Salsa and Borosilicate pages publish no hot-pour limit — follow the jar supplier's instructions and ask us on WhatsApp before pouring hot. Different waxes poured at their own page temperatures is part of what each wax is; comparing waxes without changing several variables explains why that is fair and what must stay identical.

How long does design C take? With the example checkpoints, stage 1 needs its 7-day photographs before stage 2 starts, and both stages need their 30-day photographs before a final decision. Run stage 2 straight after stage 1's 7-day read, and the whole qualification fits in about five weeks — which, with Diwali on Sunday 8 November 2026, means a festive range poured in a new wax this year is already tight. That is not a reason to skip shapes. It is a reason to keep this year's festive range in the wax you have and qualify the new one properly for the November–February wedding season.

The qualification sheet

One sheet per stage. The example house scale grades each jar 0–4 from its four photographed sides; use your own scale if you already have one, and keep it the same for every jar and every stage. No industry standard exists for an acceptable wet spot, so your acceptance rule — written before pouring — is the standard.

An example acceptance rule: "a wax qualifies in a family if no jar grades above 1 at 7 days and after the cycle, and the arm is no worse than the control on any jar". The second half matters: a candidate that is merely as good as your current wax in a hard jar has not earned a switch on adhesion alone. Choosing when one wax adheres and another throws and the section capstone show how adhesion sits beside throw, frosting, burn and heat in the final choice.

The design C kit, line by line

Design C with Chunks as the illustrative stage-1 winner. Grams use the CSI convention (oil = W × L) and a 5% pour-loss allowance; jars are bought in their smallest listed packs. The Borosilicate 600 g jar is listed with limited stock — confirm on WhatsApp before planning more than a test quantity. Strike off any jar you already hold.

If CSI 468 wins stage 1 instead, the stage-2 wax changes and the total becomes ₹7,396.48. Either way the oil is the reader's choice; Fresh Strawberries is used here as the example oil; at about 507 g of need, 1 × 500 g + 1 × 15 g is the cheapest listed cover — a design this size is past the 15 g / 50 g sample stage. CSI publishes no adhesion or throw data for any oil. Wick lines are examples: CSI publishes no wick size for any of these jars, and the 600 g jar may need more than one wick — that is a burn-test question for your own records, kept separate from the adhesion jars.

What skipping the shape test can cost

The case for design C is the cost of being wrong. Suppose the maker skipped stage 2, bought production wax on the strength of the Clear 150 g result and poured 50 Borosilicate candles before seeing spots. At 8%, each is 48 g of oil and 552 g of wax: at the 5 kg Chunks rate (₹599.00/kg), the 1 kg Fresh Strawberries rate (₹3.54/g), an example wick at ₹5.90 and the jar at ₹200.00, that is ₹706.47 a candle in CSI materials, or ₹35,323.40 for 50 — before labour, labels and the discount needed to sell a spotted premium jar.

Against that, stage 2's Borosilicate arms cost ₹4,306.78 in this example (winner plus control, three jars each, at test-pack rates). The test is cheaper than the mistake it prevents by a wide margin, and the gap widens with every candle in the run. Calculating the cost of cosmetic rejects turns your own reject counts into that number.

The decision rule

Even the last line is not the end of qualification. A wax change re-opens wick, load, cure and hot-throw validation in every jar family; the retest post sets out which results survive and which repeat. Adhesion qualifies a wax for appearance. It does not qualify it for burning.

The CSI products in this qualification

Frequently asked questions