What Percentage of Wet Spots in a Pilot Batch Is Acceptable for a Luxury Clear-Glass Candle?

No industry figure exists — so write your own, in three parts

There is no published industry threshold for wet spots in clear-glass candles — not in India and not elsewhere. CSI does not publish one, the wax pages do not contain one, and any figure you read in a forum is somebody's house standard. That is not a gap to be embarrassed about; it is the normal state of an appearance criterion. A luxury brand whose customers photograph the candle on a bathroom shelf needs a stricter rule than a market-stall brand selling at a lower price, and both are right for their customers. The useful work is turning "luxury" into a written rule that two people would apply the same way, and then sizing a pilot that can actually test it.

A usable house standard has three parts. First, a defect definition: what counts as a spotted jar — which grade on your scale, seen from which sides, at which checkpoint. Second, a target rate: the share of production your brand can tolerate showing that defect, chosen from customer expectation and the money each defect costs. Third, a pilot plan: how many jars you pour and how many spotted jars you allow before the wax or process fails. The first part is judgement, the second is economics, and the third is arithmetic — which this page does exactly.

The worked example uses the 200 ml Salsa Glass Jar, golden lug cap — a clear jar whose fill CSI does not publish, so the maths runs on a labelled example fill of 160 g: 12.8 g of Bergamot Amber and 147.2 g of wax at 8%. Weigh your own fill and replace it. The wax is Premium Coconut Soy Wax CSI 468, poured at its page's 58–60°C; the Salsa's page publishes no hot-pour limit, so follow the jar supplier's guidance and ask CSI on WhatsApp if unsure.

Part one: define a spotted jar so two people agree

Most arguments about wet spots are arguments about definitions. One person counts a pin-head spot near the base as a defect; another only counts patches visible from the front. One looks on pour day, another after a week on the shelf. Before you set any percentage, decide what a spotted jar is, in words and with a reference photograph. A wet spot is commonly described as an area where wax has separated from the glass, leaving a thin air gap that looks darker through clear glass — it is not liquid — so your definition is about how much of that you can see, from where, and when.

A practical way is a 0–4 grade scale with photographs pinned beside the scoring station: 0 no spot from any side; 1 one spot under 1 cm across; 2 several small spots or one up to 3 cm; 3 patches covering about a quarter of the wall; 4 pull-away over a third or more. Then the defect definition picks a grade and a view — "grade 1 or worse on the front face" is a strict luxury rule; "grade 2 or worse from any side" is looser. Estimate the affected glass area with a printed grid or a marked acetate sleeve held against the jar when two scorers disagree. What to record when comparing waxes and how much variation is normal give the background; customers who think spots are oil explains why the front face matters most.

Part two: choose a target rate from money and from your customer

The economic side is straightforward to compute. In this format each candle carries ₹198.76 in CSI materials — 147.2 g of CSI 468 at the 5 kg rate, 12.8 g of Bergamot Amber at the 1 kg rate, an example Eco Thin C1 wick at ₹5.90 and the Salsa jar at ₹29.50. Add a labelled example of ₹60.00 for your labour and packaging per candle (replace it with your own). If spotted candles are scrapped, the cost of each full-price candle is that total divided by (1 − reject rate). If they are hidden or discounted instead, the cost moves into labels or lost revenue — shown separately, because the two treatments are different decisions.

Read down the first column. Going from 0% to 2% adds ₹5.28 to each sellable candle; from 2% to 10% adds another ₹23.47; at 30% the candle costs ₹369.66. Money alone rarely forces a very low target — a few per cent of scrap is cheap. What forces it is the customer. A luxury clear-glass candle is judged before it is lit, often in a photograph shared with others, and one visibly patchy jar on a retailer's shelf can cost more than the scrap arithmetic shows. That judgement is yours; cost per visually acceptable candle and counting discounts and complaints help put money on it.

A useful way to choose: write down the rate at which you would stop selling the line as "luxury clear glass" and switch to a frosted jar or an opaque label — the frosted-jar post and the label-cost post price those alternatives. Your target sits comfortably below that point. For many premium brands that lands somewhere in the low single digits; for a standard line it may be higher. Those are examples of how makers reason, not figures we can give you.

Part three: turn the target into a pilot plan

Now the arithmetic. A pilot plan is two numbers: n, the jars you pour, and c, the most spotted jars you will accept. Because spotting varies jar to jar, any plan can pass a bad wax by luck or fail a good one by bad luck; the question is how often. The table gives the exact chance that each plan passes, for a range of true rates in your production. The diagram above draws the same numbers as curves.

Look at what the plans do. "50 jars, none spotted" passes a 1%-rate process 60.5% of the time — it fails good waxes quite often — and still passes a 5%-rate process 7.7% of the time. "100 jars, at most two spotted" passes a 1% process 92.1% of the time and a 10% process only 0.2% of the time. More jars make the curve steeper: better at passing good processes and failing bad ones. That is the honest price of a strict luxury standard — it needs a bigger pilot.

The second table is the strictest form: if you want to say "with 95% confidence, fewer than 2% of my candles spot" on the strength of a pilot with no spotted jars at all, you need 149 clean jars; for 1%, 299. Nobody should pour 299 candles before buying a bag of wax. The practical route is a 50–100 candle pilot with a plan from the first table, then continued monitoring in production — monitoring future lots — so evidence keeps building after approval. The pilot post covers how to run it so it tests production, not you.

The priced pilot at both sizes

The Salsa jar makes larger pilots affordable: its packs of 50 and 100 bring the jar to ₹29.50 each. Each candle takes 147.2 g of CSI 468 and 12.8 g of Bergamot Amber at the example fill; quantities include a 3% pour-loss working allowance. The pilot is production, so it uses the cheapest production packs, including the 5 kg bag.

Doubling the pilot from 50 to 100 jars adds ₹10,278.02 in CSI materials — and, as the plan table shows, buys a much sharper test. Pilot candles that pass are sellable, so the real cost is the candles that fail plus your recording time. Add ten control jars of your current wax in the same racks from your own stock.

The decision rule

Apply from the top. Once a wax passes, the standard does not retire: the same definition and grade sheet become the release check for every production batch. Locking the process writes them into the SOP and the scorecard puts appearance beside throw, burn, heat stability and labour.

The CSI products in this pilot

Where this fits in the qualification

This page owns the threshold — what "acceptable" means and how many jars prove it. Jar counts for the first screen, checkpoints and the storage hold come before; the pilot applies the plan; and the series capstone shows the whole path.

Frequently asked questions