Burn time claims

By Mohamad Sinno, Charcoal Expert · published 7 September 2026. Not reviewed by the Head of QC — the reviewer byline on our older quality pages carries the date those pages were read, and this one has not been read yet.

Burn time is the most advertised property of shisha charcoal and the least defined. There is no standard method behind any published figure, ours included — which is why this page gives you the conditions a claim has to state instead of another number to add to the pile.

The short answer

Treat a burn-time figure as unusable until you know the piece's weight, how it was lit, what it sat in, what the air was doing, the room it was in, and what counted as the end. Suppliers publish the figure and omit the six; the figure is the part that costs nothing to produce.

This is not a reason to ignore burn time. It is a reason to generate your own, under your own stated conditions, on samples from suppliers you are actually choosing between.

The six conditions a claim must state

Six conditions, and the published claims in this market state roughly one of them — the size. That is the whole finding, and the rest of this page is the evidence for it.

The teardown: what the published figures rest on

One producer publishes a measurement process, which is more than most: "Igniting a single briquette or a known quantity of charcoal / Allowing it to reach peak combustion / Recording the total time until the briquette extinguishes naturally or becomes non-functional for heating", adding that "In high-precision contexts, tests may be repeated under constant airflow and humidity conditions to ensure consistency." Its figures follow — "Typically burn for 60 to 90 minutes per piece, depending on size and density" and "A well-produced 25mm coconut shell cube can burn for up to 90 minutes under optimal conditions" (omnicococharcoal.co.id, 6 November 2025).

Read the process against the checklist above and the gaps are its own: no mass, no ignition duration, no foil-or-device setting, no ambient — and "non-functional for heating" is never defined, which is the endpoint. "Optimal conditions" names none of them. It is the most transparent version of the claim on this SERP and it still cannot be reproduced from what it says.

A retailer's version drops the process and keeps the numbers: "flat shape size 25x25x15mm (1″x1″x0,6″) should be lasting enough for more than 60 minutes. While cube shape size 25x25x25mm (1″x1″x1″) must be lasting more than 90 minutes of hookah session", plus "Temperature and Flame stability: 40 – 45 minutes" and an ignition of "around 7 to 10 minutes" (charcoalkings.com.au, 8 October 2023). Useful as a market expectation. Unusable as a measurement: the only condition stated is the size.

Both are cited here as dated conventions — what the market says, when it said it — and neither is evidence about a batch you would receive from anyone, including the publishers.

Where a stated airflow does exist

Airflow is the condition nobody in the trade states, and the only numbers for it come from smoking research. A study using a research-grade waterpipe recorded puffing continuously and reports mean flow rates of 12.11, 11.66, 11.81 and 11.24 litres per minute across four arms, with puff volumes of 0.63–0.74 L, puff durations of 3.04–3.62 s and interpuff intervals of 21.0–27.9 s (ClinicalTrials.gov NCT05453773, results posted 31 December 2024; the study is completed).

That is a health-research instrument and not a charcoal standard, and we are not proposing it as one. It is worth knowing for exactly one reason: it is the only place in this entire evidence base where somebody wrote down what the air was doing. Every burn figure you have been quoted was produced in air that nobody described.

Why we publish no figure of our own

The drying log and the container loading log are not published, and no sample page of either has been supplied. So there is no log to show either — the gap is in the record, not just in the publishing.

What we do publish are the parameters that do have methods behind them, on certificates you can check with the laboratory: ash content, moisture, and fixed carbon and volatile matter. Fixed carbon is the parameter most closely related to how a piece holds heat, and unlike burn time it is measured to a stated method — which is the trade a buyer should want.

A burn-time clause you can actually enforce

If burn time has to be in the contract, make it a procedure rather than a number, or it will be unarguable on the day it matters:

1. Write the six conditions into the clause, not the duration alone. A clause that says only "minimum X minutes" has no method and cannot be breached or satisfied.
2. Name who runs it and on what. Pieces from a numbered batch, drawn how, by whom, with the carton code recorded.
3. Agree the endpoint in words before the first shipment. Most disputes about duration are disputes about when to stop the clock.
4. Tie it to the claims window. Ours is seven days from receipt with replacement or credit as the remedy; a burn-time finding that arrives afterwards is a conversation, not a claim.
5. Put the measured parameters in the same clause. Ash, moisture and fixed carbon carry methods and a laboratory. They are what makes the rest of the paragraph enforceable.