A charcoal lab report tells you four things that predict how the charcoal will burn: how much of it is carbon, how much is ash, how much will come off as smoke, and how much is water. Read the fixed carbon first, then ash and volatile matter, and always check whether the figures are given as received or on a dry basis. This guide walks through each line using one of our own reports as the example.
The four numbers that add up to 100
A proximate analysis splits the sample into four parts by weight:
- Moisture: water in the sample. You pay for it and it does not burn.
- Volatile matter: what is driven off as gas and tar when the sample is heated without air. On the grill this is the source of smoke, flame and smell.
- Ash: the mineral residue left after everything else has burnt.
- Fixed carbon: what remains. It is not measured directly; it is calculated as 100 minus the other three.
Fixed carbon is the part that glows and gives heat. The higher it is, and the lower the volatile matter and ash, the cleaner and steadier the charcoal burns.
A worked example
These are the figures from a Report of Analysis issued for our binchotan by the Sucofindo laboratory in Surabaya on 27 July 2026, tested to ASTM D1762-84:
| Parameter | As received | Dry basis |
|---|---|---|
| Total moisture | 2.05 % | – |
| Ash content | 1.92 % | 1.96 % |
| Volatile matter | 3.28 % | 3.35 % |
| Fixed carbon | 92.75 % | 94.69 % |
| Total sulfur | < 0.02 % | < 0.02 % |
| Gross calorific value | 7,886 kcal/kg | 8,051 kcal/kg |
Check the arithmetic on the as-received column: 100 − 2.05 − 1.92 − 3.28 = 92.75. If the four lines of a report do not add up to 100, ask why.
As received and dry basis
As received (AR) describes the sample exactly as it reached the laboratory, water included. Dry basis (DB) recalculates every figure as if the water had been removed, by dividing by the dry fraction. In the example, 92.75 ÷ (1 − 0.0205) = 94.69.
This matters when you compare suppliers. A dry-basis figure always looks better than the as-received figure for the same charcoal, and the gap widens as moisture rises. Compare dry basis with dry basis, and look at the as-received moisture separately, because that is the water you will be shipping.
What each figure means in the kitchen
- Fixed carbon. White charcoal typically tests above 90 %. Ordinary black lump charcoal is commonly well below that, with the difference showing up as volatile matter.
- Volatile matter. Low single digits mean very little smoke from the fuel itself. High values mean flame and smoke while the charcoal lights and burns in.
- Ash. Lower ash means a cleaner fire bed and less clearing out during service.
- Moisture. Charcoal takes up water from the air, so moisture reflects storage and packing as much as production. High moisture makes lighting harder and can cause sparking.
- Calorific value. The heat released per kilogram. It rises and falls with fixed carbon.
- Sulfur. Wood charcoal is naturally low in sulfur. The line is there because the same analysis is used for coal.
Five checks before you trust a report
- Who issued it. An independent, accredited laboratory carries more weight than an in-house sheet.
- The date. A report describes one sample at one time. Ask for a recent one.
- The sample description. It should match what you are buying. The sample is supplied by the producer, so the report proves what that sample was, not what every carton will be.
- The test method. Results from different methods are not always comparable. ASTM D1762 is the standard method for wood charcoal.
- The basis. Make sure you know which column you are reading.
What a report cannot tell you
It says nothing about stick size, how much breakage there is in a carton, or how consistent one shipment is with the next. For those, ask for a sample carton and photos of packed goods, and agree on the size grade in writing. Our importer's checklist covers the rest of the buying process.
Looking for a binchotan supplier?
CV. ABRA produces binchotan white charcoal in Indonesia in sizes S, M and L, minimum one 20 ft container FOB Surabaya. See the product range or request a quote.
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