Should I Photograph the Glass After Every Burn Cycle When Qualifying a Wick for Commercial Production?

Why every session, not just the end

Your question, restated: you're qualifying a wick for commercial production, burning candles to the bottom over a week or more, and wondering whether a photo after every burn cycle is worth the bother. It is, for four reasons. Soot accumulates. A rim band that is 2 mm after session 2 and 11 mm after session 5 is a trend; a single photo at the end only shows the total, not whether it came from one bad evening or steady growth. Problems belong to thirds of the jar. A wick that is clean at the top and marks the glass only in the bottom third is a different decision from one that marks from the start (the late-jar soot hub), and only photos from every session show which. Memory flatters. On day seven, "it was fine at the start" is a feeling; a photo is evidence a second person can check. Records outlive the test. When a customer sends a photo of black glass in four months (the customer-photo questions) or you change wick packs, the qualification strip is what you compare against.

The photos also catch things your eyes skip during a burn: a flame that leans the same way every session (a draught or an off-centre wick), a pool edge that leaves a ring until session 3, a cap that grows faster in one candle than the others. None of this needs special equipment. It needs the same picture taken the same way, every time.

The photo station: a phone, a stand and a white card

The aim is that two photos of the same rim, taken a week apart, differ only because the rim changed. Every element below removes one source of difference. The distances are a worked example; what matters is that you mark yours and never move them during a test.

The shot list, and the ID card in every frame

The shot list is built around what changes during a burn and what the approval rule needs to see. Each shot has a fixed position and a code, and the code goes into the file name.

The ID card is a small index card propped in the corner of every frame, written in thick marker: job, wick, candle, session, hour or shot, date, and the weights before and after. It costs nothing and it saves the test: a photo with its ID in the frame still says what it is if the file is renamed, sent on WhatsApp or printed. Add the room temperature and anything unusual ("fan came on at 3 h") on the back of the card and photograph that too if it matters.

Over a full two-arm test that is a lot of pictures: 6 candles × about 7 sessions × 7 shots is about 294 photos. Worked example: at 3.0 MB each that is about 0.86 GB, which fits on most phones, but back it up to a computer or cloud folder after every session. Photography takes about 12 minutes per session for six candles once the station is set, most of it waiting for candles to cool.

File names, folders and the log

Name every file in five parts, as in the diagram: job_wick_candle_session_shot, for example J12_C1_B2_S05_RIMF.jpg: job 12, wick C1, candle B2, session 5, rim front. Keep the session number two digits (S05, not S5) so files sort in order. Rename on the computer at the end of each session, checking each file against the ID card in its frame; the phone's own names are useless after a day.

The strips are where the photos earn their keep. Lay the RIMF shots for candle A1 from S01 to S07 in one row, A2 and A3 below, then the B candles, and the comparison is instant: a band creeping down the glass in every A candle, clean B rims, one odd candle. Any free photo-collage tool will do, or print them small. If you are comparing two wick suppliers rather than two sizes, what to record beyond melt-pool diameter lists the other measures worth logging alongside.

Reading the photos: what each strip reveals

Read the strips before you read the grades. Worked example, labelled: a rim band measured against the ruler at 4 mm after session 2 and 11 mm after session 5 in all three A candles, while all three B candles stay clean, is the clearest possible picture of a wick with no margin. Ranked by how often each pattern explains what you'll see (our judgement; signs are common observations, not CSI burn data):

Two things photos are bad at. Fine grey haze: a faint film is easy to miss and easy to imagine; that is why the tissue shot and a physical white card exist, and why grading needs a reference set (how much soot is acceptable). Colour changes in the wax: yellowing or darkening of the wax itself, common with vanillin-rich oils and light exposure, is not soot; note it, but don't grade it as a combustion fault. Cause 6 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.

How the photo set feeds approval

The test itself is the usual one, using the series' default test candle, labelled: 200 g at 8% = 16 g fragrance + 184 g wax (load as a percentage of total weight), in your production jar. Two arms of three (6 candles: current wick and one CSI rung down), 4-hour sessions (a common care-label maximum, labelled), trimmed to 5–6 mm at the start, still air, burned to about 1 cm from the bottom, with top, middle and bottom judged separately. The pre-approval design with margin candles is the black-rim pre-approval test; this section is about how the photos plug into whichever design you run.

The CSI buy list and the step to production

CSI's sized, tabbed wicks are three rungs: C1 → C2 → Cotton Braided. Arm B is one rung down: 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 the strips show soot on one rung and a tunnel on the next, the finer step is on the formula side (a lower load on the current wick), or ask us on WhatsApp; we'll say plainly if we have nothing between.

Argued against our own interest: the photo method itself needs nothing from us, and if you are documenting a wick you already trust, you need no arm B either. 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; the C2 → C1 step saves ₹3.54 a candle, never a reason by itself.

The step to production quantity

Production wicks = candles × wicks per candle × (1 + a defect allowance). Worked example, labelled: 150 single-wick candles a month with a 2% allowance is 153 wicks. On C1, 100 + 3 × 20 = 160 wicks cost ₹944.00; on C2, 100 + 50 + 10 = 160 cost ₹1,510.40. Keep the station: two audit candles a month from production, one 4-hour session each, photographed with the same seven shots (14 photos a month), compared against the qualification strips, catch a drifting wick lot or oil lot early. 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 that make photo-logged qualification work, chosen on page statements, price and stock on 7 October 2026. CSI publishes no soot, flame or glass data, so nothing is ranked on performance, and each card says when not to buy.

Skip for now: any camera or lighting kit (a phone and a lamp are enough); production wick packs before the strips reach the floor; the Cotton Braided pack if your jar is 8 cm or narrower and you're already on C2; and a non-contact thermometer from us, because we don't list one.

Frequently asked questions