My Customer Sent a Photo of Black Glass but I Cannot Reproduce It — What Burn-Behaviour Questions Should I Ask Before Changing the Formulation?
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Then what? Replay their evening on candles from the same lot. Burn three under their conditions (their session length, their trim, their fan) and three under your label conditions, with one retained candle in each arm. That separates how it was burned from how it was made.
When do I change the formula? Only if your own label-conditions arm soots. More than one independent complaint on the same lot or scent is a reason to test harder (their longest burn, a fan arm), not to change blind. Soot only under their conditions is a care-instruction problem. Retains that soot when fresh candles don't is a lot problem.
What does it cost? A replay with two retains needs four fresh candles: one 1 kg pack of Luxury Soy Wax CSI 464 (₹507.40) plus your own oil and jars. Wicks come only after outcome B: from C2, the Eco C1 20-pack (₹118.00).
- Straight answer: what to ask before changing anything
- What the photo can tell you, and what it can't
- The twelve questions, and what each answer points to
- Their evening or your formula: the causes, ranked
- Replaying the customer's evening on the same lot
- Change the formula or not: the decision rule
- Retains by lot: what to keep and why
- The CSI buy list and the step to production
- What to buy, and what to skip
- Frequently asked questions
What the photo can tell you, and what it can't
Start by reading the photo for the one thing it does show reliably: the pattern. Soot rises in the hot plume above the flame and settles on the coolest surface it meets, so where the black sits is a clue. A band all round the inside rim that thickens burn after burn is the classic pattern of a flame drawing more fuel than it burns cleanly: a long wick, a capped wick, a long session, or a wick with no margin. A streak on one side only, often with a one-sided melt pool, commonly points to moving air pushing the plume against that wall. Black only on the inside of the lid, with clean glass, often means the candle was lidded while lit or immediately after: extinguishing smoke, not burning soot (extinguishing smoke versus burning soot). A dark film low in the jar, near the end of its life, is the late-jar pattern from the soot hub, where heat builds and the flame sits closer to the glass.
What the photo can't show is duration, trim length, airflow, how the flame looked, or which of your batches it came from. Phone cameras also exaggerate or flatten dark films depending on light, and on matte or tinted glass a thin film may barely show. So read the pattern, write down your first guess, and then ask before you act on it. Never ask a customer to touch the glass to check heat or soot; ask for photos.
| Where the black is | Commonly linked to | Ask especially |
|---|---|---|
| Even band round the inside rim | Long burns, long or capped wick, or a wick with no margin | Questions 1, 3 and 8 |
| One side, streaky | Draught from a fan, AC, cooler or window | Questions 4 and 5 |
| Inside the lid only | Lid put on while lit or still smoking | Question 6 |
| Low in the jar, late in its life | Heat build-up as the wax falls | Questions 8 and 12 |
| Whole glass grey, outside too | Crowding, another flame, or a room source | Question 11 |
The twelve questions, and what each answer points to
Customers answer short, friendly questions; they ignore forms. Send these as one message, numbered, and ask for three photos: the wick close up, the candle from the side with a coin or ruler beside it, and the place it stood. Each answer either points towards how the candle was burned or towards the candle itself.
| No. | Question | Why you ask | Points to the evening | Points to the candle |
|---|---|---|---|---|
| 1 | How long did it burn each time? What was the longest single burn? | Duration is the commonest trigger for rim soot | Longer than your label; "all evening" | Within your label time |
| 2 | How long was the very first burn? | A short first burn leaves a tunnel and a deep, narrow pool later | Under an hour, often | Full pool on burn 1 |
| 3 | Did you trim the wick before lighting? Can you send a close photo of it now? | A long or capped wick makes a taller, sootier flame | Never trimmed; big carbon cap | Trimmed; short, clean wick |
| 4 | Where did it stand? Near a ceiling fan, AC, cooler, open window or door? | Moving air makes the flame flicker and smoke | Under a running fan or near a vent | Still room, nothing running |
| 5 | Did the flame flicker, lean or dance? | Flicker is the visible sign of a draught | Yes, constantly | Steady teardrop |
| 6 | How did you put it out: blew, snuffed, dipped, or put the lid on? | Blowing and lidding make extinguishing smoke; a lid on a lit candle is a safety issue | Lid on, or blown hard | Snuffed or dipped |
| 7 | Where exactly is the black: all round the rim, one side, inside the lid, near the base? | The pattern points to the cause | One side (draught); lid only (extinguishing) | All round, rising each burn |
| 8 | When did it first appear: first burn, after several, near the end? | Late-jar soot is a different mechanism | Only one long evening | Every burn from the top |
| 9 | When did you buy it, and when did you first light it? | Candle age and storage | Kept in a hot spot for months | Recent, stored normally |
| 10 | What lot or batch number is on the base or label? | Links the photo to your pour records and retains | — | A lot with other complaints |
| 11 | Was anything near or over it: another candle, a shelf, a lampshade? | Crowding and heat sources change the flame | Candles side by side, shelf above | On its own |
| 12 | How much wax is left? A side photo with a coin or ruler beside it. | Lets you estimate hours burned | More used than their story | Matches their story |
Two answers matter more than the rest. Question 1, because a candle that is clean at four hours can soot at six, and many customers burn through an evening without looking at the clock; soot only after four hours or longer weighs whether that should change your wick approval. Question 4, because in Indian homes the ceiling fan is often on whenever someone is in the room, and a correctly sized wick can still soot under one (fan or AC soot with a correct wick). If you sell through a shop, ask the shop the same twelve questions about its display shelf: a candle burned all day under an AC vent tells you about the vent.
Their evening or your formula: the causes, ranked
Ranked by how often each explains a complaint you can't reproduce (our judgement; the very fact that your tests are clean favours the evening). Signs are common observations, not CSI burn data.
| Cause | What you'd see or hear | Discriminating test | Fix | Cost |
|---|---|---|---|---|
| 1. Burns longer than your label (evening: duration) | Q1 "all evening"; Q12 wax used exceeds their story | Arm C at their session length beside arm L at yours | Care line with your tested maximum; reconsider the wick if your label allows long burns | Nothing; stickers from ₹413.00 |
| 2. Fan, AC or window (evening: airflow) | One-sided streak; "it flickered" | Arm C with a fan at the distance they describe | Placement advice on the label and in your reply | Nothing |
| 3. Never trimmed, or a big cap (evening: trimming) | Q3 wick photo long and capped | Arm C started untrimmed at their wick length | Trim line; check whether your wick tolerates one skipped trim | Nothing, or a cutter from ₹177.00 |
| 4. Lidded or blown out (evening: extinguishing) | Lid black, glass clean; Q6 "put the lid on" | Extinguish one replay candle both ways and compare the lid | "Snuff or dip, don't lid a lit candle" in the care line | Nothing |
| 5. Wick with no margin (candle: wick size) | Black band all round within your label conditions | Arm L soots: then current wick against one CSI rung down | Step down one rung, if it still reaches the glass | ₹118.00 (C1 20-pack, from C2) |
| 6. That lot differed (candle: lot) | Complaints cluster on one lot; Q10 | Retains from that lot against fresh candles, same arm | Hold the lot; compare wick pack, oil lot and pour records | Your retains |
| 7. Heavy oil, high load or dye (candle: formula) | Complaints on one scent or colour only | Same wick, that scent against a lighter one | A per-fragrance wick, or a lower load within both ceilings | Your own oils |
| 8. Candle age or storage (candle: handling) | Old stock, stored hot; Q9 | A retain of the same age against a fresh pour | Rotate stock; note storage on your records | Nothing |
Cause 7 is a tendency, not CSI data: vanilla-rich, resinous and dark gourmand oils, higher loads and heavy dye commonly build more carbon, and no CSI oil or dye page gives soot data in the text we captured. If the complaint is scent-specific, the vanilla-versus-lavender post sets up a per-fragrance test. Cause 6 is why lot numbers matter: a change of wick pack or supplier can shift a flame without any change to your recipe (compare wick lots first).
Replaying the customer's evening on the same lot
This is a short, targeted replay of one complaint, not the full commercial reproduction design; if you need that (arms for airflow, hourly wick measurements, replicate counts for a recurring fault), it is how to reproduce smoking during commercial testing. The replay uses the series' default test candle where you have to pour fresh, labelled: 200 g at 8% = 16 g fragrance + 184 g wax (load as a percentage of total weight), in the same jar the customer had.
| Item | Need | Buy | ₹ |
|---|---|---|---|
| Retains from the lot | 2 | From your shelf | already paid |
| Wax for fresh candles: Luxury Soy Wax CSI 464 (or yours) | 736 g | 1 kg (264 g spare) | ₹507.40 |
| Fragrance: the complaining scent | 64 g | From stock, same lot if you have it | your own |
| Wicks and jars | 4 each, your current spec | From stock | your own |
| If outcome B: ladder wax | 552 g more (1,288 g in all) | A second 1 kg, or 2 × 1 kg at the start | ₹1,014.80 for both |
Change the formula or not: the decision rule
Changing a wick, load or oil because of one complaint is tempting, especially when a customer is upset. But a formula change resets your testing: the new wick has to pass to the bottom of the jar before you can sell it, and it can create a new complaint (a smaller wick tunnels, a lower load throws less). The replay is how you earn the change.
| Replay result | Other complaints | Decision | What you change |
|---|---|---|---|
| A: soot in arm C only | None | Keep the formula | Reply with care advice; check your label carries the session length, trim and placement |
| A: soot in arm C only | Two or more, all long burns or fans | Keep the formula, rethink the margin | Your label line, or test whether one rung down holds in their conditions (the four-hours post) |
| B: soot in both arms | Any | Change the wick, after a test | One-rung-down ladder, three candles, full life, arm L as the control |
| C: retains soot, fresh don't | Same lot | Hold the lot | Find what differed in that pour (wick pack, oil lot, temperatures); the recipe may be fine |
| D: nothing soots | None | Change nothing | Ask for the wick, flame and room photos; keep the file open |
| D: nothing soots | Two or more, same scent | Test that scent again | Re-run with the customers' longest reported burn and a fan arm |
Argued against our own interest: when your own tests are already clean, outcome A or D is the likelier result (our judgement), and neither needs anything from us. If the replay is clean, the money you'd have spent on a new wick test is better spent on a clearer care line and a kind reply to the customer.
Retains by lot: what to keep and why
You can only replay a complaint on the same lot if you kept some of it. A simple retain policy, our judgement and labelled: keep 2 candles from every poured batch, numbered with the lot, stored with your stock, and a lot sheet that records what made that batch different from the last one. Worked example: in a 50-candle batch that is 4% of the batch. In CSI materials, one retained 200 g candle is about ₹186.34 before the jar (₹93.36 of Luxury Soy Wax CSI 464 at the 10 kg price, ₹83.54 of Lavender at the 1 kg price, and one C2 at ₹9.44), so two cost about ₹372.68 per batch. That is your insurance premium against a wrong reformulation.
| Field | Example entry | Why it matters for a soot complaint |
|---|---|---|
| Lot number | L-1007-A | Matches the customer's base label to this line |
| Pour date and count | 7 Oct, 50 candles | Candle age, and how many customers share the lot |
| Wax, pack and date bought | CSI 464, 10 kg, bought 1 Oct | A new wax lot is a variable |
| Fragrance and load | Lavender, 8% | Scent-specific complaints |
| Wick and pack | Eco C2, 100-pack opened 3 Oct | A new wick pack or supplier is the first suspect in outcome C |
| Dye and dose | none | Heavier colour, more carbon (tendency) |
| Jar batch | bought 28 Sep | Glass varies between batches |
| Add and pour temperatures | 85°C / 82°C | Pouring outside the wax page's figures |
| Retains and where | 2, shelf B | So you can find them in three months |
| Complaints | date, customer, outcome A–D | Two independent complaints on one lot changes the decision |
How long to keep retains is your call; until a few months after the last candle from that lot has sold is a common habit (judgement). Mark the lot on every candle you sell. CSI lists no lot or batch labels: a printed sticker of your own, or a marker on the base, does the job. If a supplier lot is the suspect, change control is the right frame: what to retest when you change wick supplier.
The CSI buy list and the step to production
Wicks enter only at outcome B. Then the ladder is your current wick (arm L is already the control) against one CSI rung down, three candles. CSI's sized, tabbed wicks are three rungs: C1 → C2 → Cotton Braided. One rung down is Cotton Braided → C2, C2 → C1, or a C2 pair → a C1 pair. There is no sized, tabbed wick between C1 and C2 or between C2 and Cotton Braided, no smaller sized, tabbed wick than C1, and one wooden-wick listing with no widths. If one rung down tunnels in your jar, ask us on WhatsApp, test a lower load on the current wick, or accept the label route for long-burning customers.
| Current wick | One rung down | Pack and price | Per wick | Left after 3 candles |
|---|---|---|---|---|
| Cotton Braided | C2 | C2 10 ₹94.40 | ₹9.44 | 7 C2 |
| C2 single | C1 | C1 20 ₹118.00 | ₹5.90 | 17 C1 |
| C2 pair | C1 pair | C1 20 ₹118.00 | ₹5.90 | 14 C1 |
| Performance Wooden | C2 (no narrower wood) | C2 10 ₹94.40 | ₹9.44 | 7 C2 |
| C1 single | Nothing smaller: a lower load instead | Your own stock; ask us | — | — |
Argued against our own interest: at outcome A the purchase is a care line, and possibly nothing at all if your label already says it. And because C1 (₹5.90), C2 (₹9.44) and Cotton Braided (₹12.00) cost the same per wick at every pack size, a bigger pack buys stock, not savings. Stepping C2 → C1 saves ₹3.54 a candle; that is never the reason to do it.
The step to production quantity
If the ladder passes, production wicks = candles × wicks per candle × (1 + a defect allowance). Worked example, labelled: 250 single-wick candles a month with a 2% allowance is 255 wicks. On C1, buy 2 × 100 + 50 + 20 = 270 for ₹1,593.00; on C2, 260 for ₹2,454.40. If you add a care sticker to every candle, one 500 roll (₹413.00) covers the month with 245 spare. Write the new wick on the lot sheet from the first production batch, keep its retains, and treat the first complaint on the new spec exactly as you treated this one: questions, replay, then decide. Reorder point = daily use × your lead time + safety stock; CSI publishes no lead times, so ask on WhatsApp.
What to buy, and what to skip
Four items, chosen on page statements, price and stock on 7 October 2026, in the order the decision path reaches them. CSI publishes no soot, flame or glass data, so nothing is ranked on performance, and each card says when not to buy.
| Roll | Price | Per sticker | Covers |
|---|---|---|---|
| Pack of 500 (1 inch) | ₹413.00 | ₹0.83 | a 255-candle month, 245 spare |
| Pack of 1000 (1.5 inch) | ₹699.00 | ₹0.70 | larger sticker; check it fits your jar or box |
| Pack | Price | Per wick | Use |
|---|---|---|---|
| Thin (C1) / 10 | ₹59.00 | ₹5.90 | Out of stock on 7 October 2026 |
| Thin (C1) / 20 | ₹118.00 | ₹5.90 | the ladder from C2: 3 used, 17 spare |
| Thin (C1) / 50 | ₹295.00 | ₹5.90 | same per wick |
| Thin (C1) / 100 | ₹590.00 | ₹5.90 | production, by the month |
| Thin (C1) / 500 | ₹2,950.00 | ₹5.90 | same per wick |
| Thin (C1) / 1,000 | ₹5,900.00 | ₹5.90 | same per wick |
| Thick (C2) / 10 | ₹94.40 | ₹9.44 | the ladder from Cotton Braided |
| Thick (C2) / 20 | ₹188.80 | ₹9.44 | same per wick |
| Thick (C2) / 50 | ₹472.00 | ₹9.44 | same per wick |
| Thick (C2) / 100 | ₹944.00 | ₹9.44 | production, by the month |
| Thick (C2) / 500 | ₹4,720.00 | ₹9.44 | same per wick |
| Thick (C2) / 1,000 | ₹9,440.00 | ₹9.44 | same per wick |
| Pack | Price | Stock | For the replay |
|---|---|---|---|
| 500 g | ₹260.00 | In stock | too little for four fresh candles |
| 1 kg | ₹507.40 | In stock | four fresh replay candles, 264 g spare |
| 5 kg | ₹2,537.00 | In stock | production, not the replay |
| 10 kg | ₹5,074.00 | In stock | production, not the replay |
| Listing | Price | Stock | Use |
|---|---|---|---|
| Candle Wick Cutter, 3 cm blade | ₹177.00 | In stock | the 5–6 mm start trim for the replay |
| Candle Wick Cutter, 5.5 cm blade | ₹295.00 | In stock | reaches the wick low in a deep jar |
| Candle Wick Trimmer, debris catcher | ₹588.82 | In stock | page: "Trim your wick to 1/4 inch before every burn" |
Skip for now: any wick before your own arm L soots; a new oil "that burns cleaner" while the lot question is open; 500- or 1,000-packs before three ladder candles reach the floor; and a non-contact thermometer from us, because we don't list one.
CandleMakingSuppliesIndia sells the wicks, wax, tools and labels named here, not finished candles. This page still tells you that a single complaint often needs nothing from us, that a sticker roll won't fix an evening the customer has already had, and that our bigger wick packs cost no less per wick, with no half-sizes and one wooden width.
Every CSI price was checked on the live store on 7 October 2026, with stock checked per pack: the Eco C1 10-pack is out of stock and is not used, and every other item priced here is in stock on that date. Page wording is quoted and attributed, including the care roll's "burning clean and strong", the trimmer's "reducing smoke and soot buildup" and the Eco wick page's "minimal soot or smoke".
The twelve questions, the photo-pattern readings, the replay rule, the decision table and the retain policy are our judgement and labelled as such. The 5–6 mm trim, four-hour session and 1 cm wax floor are common rules of thumb; the hours-from-wax-level example uses labelled figures. Fragrance and dye effects are tendencies, not CSI test data. For bulk pricing, GST invoicing, and MSDS and IFRA documentation on request, message us on WhatsApp at +91 7397976926.
Frequently asked questions
- My Candle Leaves Black Marks Around the Top of the Glass Only Near the End of the Jar — Why Can a Wick Become Too Aggressive Later in the Candle?
- My Glass Jar Turns Black Around the Rim After Every Long Burn — What Should I Test Before Approving the Candle for Sale?
- My Candle Only Soots When the Customer Burns It for Four Hours or Longer — Should That Still Affect My Wick Approval Decision?
- My Candle Burns Cleanly for Two Hours but Starts Smoking After Three — How Should I Reproduce This Problem During Commercial Testing?
- My Candle Produces Tiny Amounts of Soot Only When Extinguished — How Do I Distinguish Normal Extinguishing Smoke from Soot During Combustion?
- Could Burning a Candle Beside a Fan or Air Conditioner Cause Soot Even If the Wick Is Correctly Sized?
- How Much Soot Is Acceptable During a Commercial Candle Burn Test Before I Reject the Wick Configuration?
- How Do I Systematically Diagnose Candle Soot from Wick Size → Wick Trimming → Fragrance Load → Dye → Airflow → Burn Duration Before Replacing Raw Materials?
Customer reviews: The six reviews at the top of this page are genuine, published Judge.me reviews left by CSI customers on the product pages named on each card — Black Glass Jar with Black Lid (150 gram) (Deliveries Starting 5th Dec), Clear Glass Jar with Golden Lid (150 gram), Eco Candle Wicks, Luxury Soy Wax CSI 464 (Flakes Form) For Container Candles. They are general product reviews, not assessments of the burn and wick advice on this page. Names, star ratings, dates and products are as recorded by Judge.me and wording is unedited. "Verified buyer" appears only on reviews Judge.me recorded as verified — Monika Deep, Subhankar Roy, Biny Abraham, Soumili Gope, Jaya Sawlani. The reviews from Ashwini are published but not recorded as verified, and carry no badge. Reviews below five stars are included as published, not filtered out.
Figures verified 7 October 2026, CSI live pricing: Candle Care Stickers Roll Pack of 500 (1 inch) ₹413.00, Pack of 1000 (1.5 inch) ₹699.00; Eco Candle Wicks Thin (C1) 10 ₹59.00 (out of stock), 20 ₹118.00, 50 ₹295.00, 100 ₹590.00, 500 ₹2,950.00, 1,000 ₹5,900.00 (₹5.90 a wick); Thick (C2) 10 ₹94.40, 20 ₹188.80, 50 ₹472.00, 100 ₹944.00, 500 ₹4,720.00, 1,000 ₹9,440.00 (₹9.44 a wick); Cotton Braided Wicks Ready Made 10 ₹120.00, 1,000 ₹12,000.00 (₹12.00 a wick at every pack); Luxury Soy Wax CSI 464 500 g ₹260.00, 1 kg ₹507.40, 5 kg ₹2,537.00, 10 kg ₹5,074.00; Lavender Fragrance Oil 1 kg ₹5,221.00; Candle Wick Cutter ₹177.00 and ₹295.00; Candle Wick Trimmer ₹588.82. Every item priced here is in stock on 7 October 2026 except where marked. Per unit = price ÷ wicks, stickers or grams, two decimals. CSI lists no non-contact thermometer, no snuffer and no lot labels.
Non-price figures: "photo of black glass" and "cannot reproduce" are the reader's description (title). The 200 g test candle at 8% (16 g oil + 184 g wax, load as a percentage of total weight) is labelled; wax ceiling as the page states (Luxury Soy Wax CSI 464 up to 10%), a formulation limit, not a regulatory one. The 6.0 cm wax column, 3.0 cm drop, 7.0 g/h, three burns, 5-hour customer sessions, 50-candle batch, two retains, 250 candles a month and 2% allowance are labelled worked examples. The replay rule, decision table and retain policy are in-house protocols, not standards. Costs are materials only and exclude labour, freight, packaging and GST. Diwali 8 November 2026 is a calendar fact.