How to evaluate a charcoal sample: the scorecard method
By Mohamad Sinno, Charcoal Expert · Last updated
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The short answer
Score the sample against a written list before you form a view of it, and keep the two halves of that list apart: the values a laboratory measured, which arrive on the batch certificate, and the things you can observe at your own bench, which are cheap, repeatable and yours. Write the results down, seal an unburnt counter-sample, and only then decide. An evaluation you did not write down cannot be compared with a container six weeks later, which is the only comparison that ever matters.
The scorecard
Ten checks, and the third column is the important one. Some of these are laboratory values you are reading rather than making, some are conventions the trade uses, and some are the only measurements in the whole exercise you can take yourself. Treating all three as the same kind of evidence is how a good sample talks a buyer out of asking the next question.
| Check | What it tells you | Where the result comes from |
|---|---|---|
| Piece count per kilogram | Density and size consistency in one number, and the one you can verify with a kitchen scale. | Your bench, against the nominal packing count for the size |
| Dimensions, several pieces | Whether the press and the cutter are holding size across a run rather than on one piece. | Your bench, against the stated tolerance of ±0.3 mm per side |
| Ash content | How much non-combustible material is left. The parameter buyers argue about most. | The batch certificate; the factory also runs it in-house on a muffle furnace |
| Moisture | Storage and drying discipline, and the parameter most likely to move between the sample and the container. | The batch certificate; in-house, a drying oven |
| Volatile matter and fixed carbon | The carbonisation quality behind the burn behaviour, and the two the laboratory owns. | The batch certificate only — not measurable at your bench |
| Ash colour at full burn | A visible proxy for how completely the material has carbonised. | Your bench, and a value the factory records per sample |
| Odour once fully lit | Binder and residue behaviour. The test buyers can run and rarely do. | Your bench — a dated supplier convention, not a measurement |
| Ash texture | Fine powder against soot, read by tapping a fully burnt piece. | Your bench — a dated supplier convention |
| Cracks and breakage, hot | Whether a piece holds together in use rather than in the box. | Your bench, against the factory drop-test criterion below |
| Burning time | Useful only against a stated method: burner, ambient conditions, one piece or a full bowl. | Recorded per batch by the factory. No figure is published here — see below |
What the factory already recorded
Half of that table exists before your parcel is packed, and asking for it costs nothing. In our own plant, samples are drawn at 6 points in the process — carbonization, screening, grinding, mixing, extrusion, drying — at random, at least five pieces per 50 kg. For each one, weight, ash content, moisture, ash colour are recorded.
Those results land in a file kept per batch, which holds the laboratory COA and the factory’s own results for the batch: ash content, moisture, burning time, drop test, cracks, temperature. The drying log and the container loading log are not published, and no sample page of either has been supplied. Two of the in-house instruments are worth naming because they set what those numbers mean: moisture is run on a drying oven at 120 °c for 5–10 minutes, and ash on a muffle furnace — temperature not recorded — so the in-house ash figure is an operational check rather than a laboratory result, and the laboratory's is the one that goes on a certificate. Volatile matter and fixed carbon are laboratory values only.
A COA is issued for every production batch. A batch COA accompanies every sample. What a certificate does and does not settle, method by method, is on how to read a certificate of analysis.
Running it in one sitting
Order matters, because the destructive checks eliminate the pieces you would want for the others. Work through it once, in this sequence, on the same day.
- Paperwork first. Confirm a batch certificate came with the parcel and note the batch number. A sample with no batch record behind it can still be a fine briquette; it just cannot be traced to anything, and that is the whole point of the exercise.
- Count and weigh. Pieces per kilogram, against the nominal packing count for that size. This is arithmetic, not judgement, and it catches a size substitution immediately.
- Measure several pieces across the batch, not one, and compare against the tolerance the supplier states — ours is ±0.3 mm per side. One in-spec piece proves nothing; a spread that hugs the tolerance is the useful reading.
- Set aside the counter-sample now, before anything is burnt. Seal it, label it with the batch number and the date, and photograph it. That is the object your contract will point at.
- Burn one piece to completion in a clean white dish. Watch the ash colour as it finishes, tap the burnt piece to see whether the ash is a fine powder rather than a soot, and check whether it is odourless once every face has greyed over. These three are conventions rather than measurements, and they are described below with where they come from.
- Run the hot drop test — the method is in the next section, and it is the one check on this list that has a written pass criterion behind it.
- Write it down before you decide. Scores, photographs, the batch number. An opinion formed first will reorganise the evidence to fit it.
The drop test, and why it is hot
This is our own acceptance method, and it is written down so a buyer can repeat it and a contract can name it.
- Cube. The piece is heated until glowing red, held five minutes after heating, then dropped five times from 1.2 m onto a hard tiled surface. It must not break.
- Hexagonal. Three drops from 50 cm.
A cold drop test measures how the goods survive handling. The hot version measures something a customer actually experiences: a piece that fractures in the bowl once it is at temperature. Cracking is also one of the values recorded per batch on our side, so a disagreement about it can be settled against a record instead of an impression.
The bench observations, and whose they are
The three cheap observations above are trade conventions, and it is worth saying exactly where each was read, because in this subject the people publishing test advice are almost always selling charcoal.
- The full-burn smell test and the ash tap. Once every side glows and is coated in grey-white ash the coal should be essentially odourless, and the ash should be a fine grey-white powder rather than black soot. The same guide tells bulk buyers to ask the manufacturer for a batch laboratory report (bbqoncharcoal.com, a producer writing a buyer's guide, 18 June 2026).
- Ash colour as a carbonisation signal. Light-grey to white ash is read as the clean-burn sign and dark ash as a sign of incomplete carbonisation or added material, observed by burning a piece fully in a clean white dish (bintangbriquettes.com, a producer, 8 May 2025). That page offers no laboratory basis for the causes it lists, so the observation is usable and the explanations behind it are not.
- A published burn-test procedure exists and is worth knowing as a shape: one standardised cube on a heat-resistant stand, ignited with a standardised flame for a fixed period, then burnt freely to self-extinction, with burn time, residual ash, smoke and odour recorded (oxicarbon.com, a producer; the page carries no publication or modification date, so treat everything on it as undated). The method is the citable part. The results printed beside it are that producer's own figures for that producer's own coal, and they are not repeated here.
What the result should make you do
There are no numeric score bands on this page, and inventing a pass mark would be the same error as inventing a burn figure — a threshold means nothing without a population behind it. What the scorecard gives you instead is three shapes of outcome and a different next move for each.
- The bench agrees with the certificate. Count, dimensions and ash colour line up with the report, and the report names its methods. Move to the contract: seal the counter-sample and make it the named reference, per the golden sample clause.
- The bench disagrees with the certificate. Not automatically dishonesty — a hand-picked parcel and a production batch are different populations, which is a real and documented effect. Ask which batch the sample came from, ask for the certificate for that batch specifically, and read why bulk sometimes differs from the sample before deciding what it means.
- There is no certificate, or it names no methods. That is the answer, and it arrived before you burnt anything. A report with no method beside its values cannot be checked with the issuing laboratory, and a laboratory that will not confirm a report number is the oldest tell in the trade — the supplier scam patterns covers what that usually belongs to.
What this page does not give you
No burn minutes. Burning time is recorded per batch in the factory file, and no figure from it is published here or anywhere on this site. A burn figure without its method — burner, ambient conditions, a single piece or a full bowl — cannot be compared with anyone else's, and no such method has been recorded on our side.
No sampling standard cited. Two were pursued while this page was written. The international sampling standard named by one of the quality-inspection sources in this subject could not be read at its issuing body, and the Indonesian standards catalogue returned no briquette entry across three searches. Neither is cited, and neither number nor scope is repeated second-hand from a page that mentioned one, because a standard read through somebody else's summary is that summary. Both are open items.
No downloadable form. The table above is the scorecard; it is readable and copyable without an email address, and a file version is worth having rather than worth faking.
If something is wrong after a container arrives rather than after a sample, the window is the thing to know first: within 7 days of receipt; after that the goods are deemed accepted, with replacement or credit on the next order as the remedy. Requesting a sample and its batch certificate: free charcoal samples, or WhatsApp +62 821 3924 038. Scoring is the middle of three steps, and what arrives before it and how an approved sample becomes enforceable are in charcoal samples: getting them, testing them, making them enforceable.