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Coco Reina

What each charcoal specification figure actually means

By Mohamad Sinno, Charcoal Expert · Reviewed by Budi Dharmawan, Head of QC,

Ask AI for an importer brief:

Four figures carry almost every charcoal specification: ash, fixed carbon, volatile matter and moisture. This page is what each one means for any charcoal and how it appears on a certificate of analysis. It is deliberately not a page about our numbers — those are on what our three laboratory reports measured.

Sorting and grading
Sorting removes broken and out-of-tolerance pieces before packing, which is what keeps piece count per kilogram consistent between cartons of the same size.

The four figures, and the fifth question

Figure What it changes for you How it appears on a COA
Ash The mineral residue left after combustion. It drives how often a bowl is emptied and how much sediment a customer sees, and it rises with shell contamination and binder share. A percentage, usually as-received. The method matters: it may be ASTM or a laboratory in-house method.
Fixed carbon The share that burns as heat once moisture and volatiles are gone. The closest single proxy for how completely the material was carbonised. A percentage, and the one most often quoted on a different basis than the rest of the table — check as-received against dry.
Volatile matter What leaves the briquette as gas early in the burn. High volatiles show up as smoke and smell at ignition — the complaint a lounge hears first. A percentage. Read it with fixed carbon rather than alone; the two move against each other.
Moisture Ignition behaviour, and weight you pay for at a per-kilo price. It also moves after the factory — charcoal reabsorbs moisture in transit. A percentage measured at the laboratory, on the sample as received there. It is not the figure at your warehouse.

The fifth question is the one the table cannot answer: on what basis, by what method, in which laboratory, on what date. Two ash figures are not comparable until all four match, which is why a band quoted without a report behind it tells you almost nothing.

No international standard defines these labels

ASTM D1762-84 is a test method for the chemical analysis of wood charcoal. It defines how to measure ash, volatile matter and the rest. It does not define what to call a result — there is no body that certifies a coconut charcoal as "premium", and no register you can look a grade name up in.

So every band below is market convention, not a standard. Each carries the month it was observed and the kind of source it came from. They are useful for reading what a seller means by a word; they are not evidence that any particular batch meets it.

Figure Convention observed — not a standard
Ash Supplier listings commonly claim "premium" at ≤2–2.5% and treat above ~3% as standard grade (market convention observed across supplier listings, August 2026). No standards body defines either label.
Fixed carbon "≥80% fixed carbon" is a common premium claim; one exporter's published specification pairs "min 75% fixed carbon" with "max 3% ash" (market convention, August 2026).
Volatile matter "Smokeless" is commonly defined in trade and technical writing as volatile matter below 20% (market convention, August 2026). It is a description, not a certification.
Moisture Bands cluster loosely under 5%, but the useful comparison is against the same basis on the same method rather than against a competitor's number.
Hexagonal briquette, macro
The hexagonal section gives a briquette flat faces that sit stable on a grate or in a bowl, which is the practical difference from a round finger of the same dimensions.

The three figures we publish no number for

These three appear on most charcoal specification sheets in this trade. We publish none of them as ours, for the same reason in each case: we have not commissioned the test.

Figure Why there is no number here
Calorific value No calorimetric test exists on any of our reports. A bomb-calorimeter result would be needed before we could state one.
Burn time No recognised international standard defines it for shisha charcoal, and we run no documented in-house protocol. A number without test conditions is not comparable with anyone else's.
Drop test No defined method — drop height, sample size and breakage criteria all change the score. We have no measured result to publish.

The rule behind all three: we publish measured figures only. An absent number is a smaller problem for a buyer than a confident one with no test behind it, and it is the only version of this page that survives a technical buyer asking which laboratory produced the result.

Moisture check at the line
Moisture is checked at the line rather than only in a laboratory, because a batch that leaves the dryer wet cannot be corrected once it is packed.

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