How Do I Create a Simple Temperature-Cycle Test for Clear-Glass Candles Intended for Indian Ecommerce?

The simple version, on one screen

A wet spot is commonly described as a thin air gap where wax has separated from the glass; through clear glass it looks dark and wet, but nothing is liquid. Ecommerce parcels in India commonly warm by day and cool by night for several days, and makers commonly link those swings to new patches on arrival. A temperature-cycle test lets you reproduce that on your own bench, so you can check a new formula, a new wax lot or a process change in a week instead of waiting for customer photos.

Here is the whole method in five lines. One: send a parcel on your longest regular route with a min/max thermometer inside and read the high, the low and the days in transit. Two: turn that log into settings — a warm phase at about the logged high, a room phase on your shelf, and one cycle per day in transit plus one for margin. Three: pour ten jars from one batch: four stay on the shelf as the control, five go through the cycles, one is an untouched reference. Four: photograph all ten from four sides at the end of each room phase. Five: score every jar on a written house scale and compare cycled with control. With the example log on this page — 41°C high, 24°C low, 4 days — that is 5 cycles of 8 hours warm and 16 hours room.

That is all a small business needs. It is simple because it tests one variable — temperature cycling — against a control from the same pour, and everything else is held still. It is honest because its settings come from your own route, not from a number someone quotes for "Indian summers". We publish no cycle-test results, heat-survival figures or adhesion data for any CSI wax or jar, and no industry standard for wet spots exists, so every setting and pass line here is a labelled example or your own house choice.

Why cycling, and why a control

In general candle-making practice, wax is described as contracting as it cools and crystallises, and wax and glass are commonly described as expanding and contracting by different amounts with temperature. A warm phase and a cool phase each strain the contact between them; where the contact was weak, a patch can open or spread. Makers commonly report that a patch, once started, does not reattach without remelting. The repeated-cycle post shows how to read whether damage grows with every cycle or appears once; this page is the routine version you run again and again.

Soy candles can also pull away from glass with no temperature stress at all, a week or two after pouring — late-appearing patches covers why. That is the reason for the shelf control. If the four control jars spot as much as the five cycled jars, cycling is not your problem, and no amount of bench testing will find the fix. The reference jar does a different job: it is never touched, so if anything odd happens to the whole batch — a bad wax lot, a cleaning residue — you have one jar that shows it without any handling.

The example wax is Premium Coconut Soy Wax CSI 468. Its page states a melting point of 50–53°C, a pour temperature of 58–60°C and a fragrance load of up to 13%, and says it is "formulated for excellent glass adhesion" — the same claim the Chunks and CSI 464 pages make, so the claim cannot rank them. The melting point matters for the test itself: every warm phase must stay well below it. A closed room or cupboard is easy to keep there; a parked car in an Indian summer can run far hotter than the air outside, so measure it before you use it, and never use a space you cannot read.

Where the cycle test sits on the ladder

The full series ladder runs from "is it really a wet spot?" through glass cleanliness, glass and pour temperature, cooling, storage and courier cycling, fragrance and dye, jar glass and finally the wax. A cycle test is the instrument for one rung — storage and courier cycling — and the judge for every rung after it. Use it like this.

The routine lot check is the cheapest insurance on this page. Wax, oil and jar lots change, and nothing on our product pages promises lot-to-lot consistency — we do not publish lot data. Four jars from the first batch of every new lot, cycled beside two controls, tell you whether that lot behaves like the one you approved. Monitoring future lots builds it into a routine.

The protocol, step by step

The worked example is the series default candle: 150 g in CSI's Clear Glass Jar with Golden Lid (150 gram) at 8%, which is 12 g of oil and 138 g of wax per jar. The jar's page states an approximately 150 g fill and "safe for hot pour up to 85°C"; CSI 468's page gives a 58–60°C pour, comfortably inside that. The oil is Japanese Cherry Blossom, but use the oil you sell most — the test is about your candle.

Why five cycled jars and four controls? Because cycled jars are the arm you are judging, and a fifth jar makes "four of five spotted" a pattern rather than a coincidence; four controls give you a fair picture of what the batch does on its own. It is a working practice, not a rule. In this kit each jar costs about ₹284.50 in CSI materials, so adding jars is cheap compared with a wrong decision. For a launch decision across several temperatures, the pan-India approval post stages a larger matrix.

The scoring sheet and the pass line

Use one house scale, the same for every jar and every checkpoint. The example grades the visible wall 0–4 by eye with a printed grid or a marked acetate sleeve. It is an example of a house standard — no industry figure exists for an acceptable wet spot. A simple, defensible pass line for an ecommerce candle might be: "after the route's cycle count, no cycled jar is more than one grade worse than the worst control jar, and no cycled jar is above grade 1". Choose yours, write it on the sheet, and keep it the same for every future test so the results stay comparable.

If you want the result to be blind, have someone else number the jars and keep the arm list until all scores are written. It costs nothing and removes the temptation to see what you expect. How much variation is normal helps you choose a pass line you can defend, and what to record when comparing waxes lists what else to log if the test grows into a wax comparison.

The priced test kit

From scratch, with listed, in-stock CSI packs, oil = W × L and a 5% pour-loss working allowance: 10 × 138 g wax = 1,380 g, plus 5% = 1,449.0 g; 10 × 12 g oil = 120 g, plus 5% = 126.0 g.

That is ₹284.50 of CSI materials per jar before the IPA spray. The wax is a 1 kg + 500 g pair (₹975.00) for 1,449.0 g, leaving 51 g. The oil is a 100 g and two 15 g bottles (₹708.00); the 15 g size costs ₹6.93/g against ₹5.00/g at 100 g, so if you plan a repeat round, a second 100 g is the better buy. Non-CSI items: the min/max thermometer and whatever warm space you use. The Eco Thin C1 line is the example wick only; CSI publishes no wick size for this jar.

Making it routine: what a standing check costs

Once a formula is approved, a smaller version of the test becomes a lot check. The material cost of this example candle at production rates is ₹87.91 of CSI 468 (5 kg rate) + ₹58.10 of Japanese Cherry Blossom (1 kg rate) + ₹5.90 example wick + ₹94.40 jar = ₹246.31, excluding labour, packaging, freight and GST. The table puts a labelled example on a standing check.

Checked jars are not wasted: a passed check produces four candles you can still sell, burn-test or keep as retained samples, so the real cost is lower than the table shows. Against that, one lot that spots on arrival can cost a whole month's replacements. The discounted-stock post shows how to count that side.

The decision rule

Apply it after the 7-day re-score, from the top, and stop at the first true line.

If CSI 468 is the wax you approve, its 5 kg bag is ₹3,185.00 (₹637.00 a kilo) against ₹650.00 a kilo at 1 kg, and the 10 kg bag ₹6,370.00 (₹637.00 a kilo) — a small real step. Anything larger is quoted on WhatsApp. Re-log your route in the hottest and coldest months and re-run the test if the readings move outside the settings you approved.

The CSI products in this test

Frequently asked questions