My Jar Supplier Is Temporarily Out of Stock — How Do I Choose an Alternative Container That Requires the Least Formulation Redevelopment?

Least redevelopment means least geometry change

Your formula — wax, oil, load, cure — does not care which jar it is in. Your wick does, because the wick was approved for a particular pool size, depth and glass. So the question "which container needs the least redevelopment?" is really "which container is geometrically closest to the one my wick was approved in?" That can be answered before you pour a single candle, with a caliper, a depth gauge and a scale. This page gives you the measurement sheet, the arithmetic that turns it into pool areas and fill heights, and an example scoring rule that ranks candidates and tells you how big a test each one needs.

Everything below uses illustrative measurements: your approved jar is a straight 7.6 cm inside, 8 cm deep, 6 mm base, 3 mm wall, clear glass, holding 200 g. Four candidates, A to D, are what a supplier might offer when yours is out of stock. None of the figures is a CSI jar's specification. Replace them with your own measurements and the method works the same.

The comparison sheet

Measure three jars of each candidate and use the average; note the range. Inside diameters at the rim, mid-height and base come from a caliper's inside jaws; internal height from a depth gauge; base thickness as outside height minus internal depth; wall thickness as (outside − inside) ÷ 2 at the fill line. The derived rows are geometry: brim volume as a frustum (π × h ÷ 12 × (D² + D·d + d²), which is a plain cylinder when the diameters match), fill height for 200 g at a labelled 0.88 g/ml, and pool areas as π × d² ÷ 4.

Read across and each candidate's character jumps out. Jar A is a slightly wider straight jar — the classic "near enough". Jar B has exactly the approved inside diameter but is taller, with a heavier base and thicker walls. Jar C matches at mid-height but tapers from 8.4 cm to 6.8 cm, so its pool at the base is 20% smaller than the approved jar's. Jar D is narrower, heavier and frosted. Which is "closest" depends on what you weight, which is what the scoring rule is for.

The substitution scoring rule

The rule below is an example, not a standard. It converts each measured difference into 0–3 points with fixed bands, multiplies by a weight that reflects how directly that dimension affects the wick, and adds them up. Change the bands and weights to suit your products — but set them before you measure the candidates, so the rule cannot be bent toward the jar you already like.

On this rule, Jar A scores lowest (6 of 38) and is the least redevelopment; Jar D scores highest (28). Two results are worth noticing. Jar B has a perfect diameter match and still does not win, because thicker walls, a heavier base and a deeper jar each change the late burns — see thicker glass, thicker base and taller jars. And Jar C, the taper, matches at mid-height, which is what a quick measurement across the middle would have told you, yet its base pool is far off — the narrowing-jar post explains why that matters most.

What each verdict keeps and repeats

The verdicts map onto the series' retest vocabulary — KEEP, CONFIRM, REPEAT, NEW. In every case your formula tests stay; only the wick-and-jar lines move.

From out-of-stock to approved: the sequence

The priced test kits

Built from listed, in-stock CSI sizes on the 24 September 2026 pull, with Luxury Soy Wax CSI 464 (rated up to 10%; CSI's melt/pour guidance 80–90°C, confirm on the product page) and Lavender as the worked example, 8% load, 5% allowance.

Decision rule

Scoring ranks candidates; it does not approve them. Approval still comes from the burn test: no worse than the approved jar on every safety line, within your jar supplier's guidance and the fire-safety standard you work to (ASTM F2417 is a commonly cited US one). CSI publishes no numeric flame or jar-temperature limit.

An approved alternative is most valuable before you need it. The backup-supplier post argues for pre-qualifying jars this way in quiet months, the approved-supplier list post shows how to write the result down so purchasing cannot swap jars on its own, and the substitution-or-wait post weighs a substitute against partial production or waiting when an order is already promised.

When the order is already promised

This page is about choosing among candidates. If you already have one substitute in hand and a fixed number of candles due, the question becomes whether that one jar is practical in the time you have, and what it does to your material quantities — the 1,000-candle post works that case, including sampling the jar lot and pricing the extra wax. For the geometry behind every score line, start at the diameter hub.

Frequently asked questions