What Actually Controls Heat Output and Burn Time
Heat output and burn time are controlled by three measurable properties: fixed carbon (more heat, longer burn), bulk density (slower burn when denser), and moisture (energy lost as steam). Fixed carbon and moisture are measured by ASTM D1762 and calorific value by ASTM D5865, so the drivers are checkable, not just claimed. Any burn-time or peak-temperature figure only means something with the piece size and test conditions stated.
Heat output and burn time are controlled by a few measurable properties — fixed carbon, bulk density, and moisture — not by marketing adjectives. Higher fixed carbon means more usable heat and a longer burn; higher density makes a piece burn slower and longer; moisture steals energy boiling itself off. The catch: burn-time and temperature numbers are method- and condition-dependent, so they only mean something when the piece size and test conditions are stated alongside them.
The Factors That Actually Matter
| Factor | Effect on heat / burn | Verified by |
|---|---|---|
| Fixed carbon | Higher fixed carbon → more usable heat and a longer burn | ASTM D1762 |
| Bulk density | Denser pieces burn slower and longer per piece | EN 1860-2 ≥ 130 kg/m³ |
| Moisture (as received) | Higher moisture wastes energy as steam → lower effective heat | ASTM D1762 |
| Volatile matter | Higher volatiles → faster flare and more smoke, less steady heat | ASTM D1762 |
| Calorific value | Energy content per kilogram of fuel | ASTM D5865 |
| Piece size & shape | Larger, denser hexagonal/pillow pieces sustain heat longer | Internal burn test, stated conditions |
Why “Burns for X Hours” Needs Conditions
A burn-time or peak-temperature figure is meaningless without the test setup: piece size, airflow, grill or device, and ambient conditions all move it. That is why we treat burn time and surface temperature as shape- and condition-sensitive and publish them only from our own burn test with the conditions stated — never as a bare “burns for X hours” claim, and never copied from an industry benchmark.
⚠ Pending accredited lab
Our measured burn time and peak surface temperature for each grade and shape are published from an internal burn test with the piece size and test conditions stated, and cross-checked against the accredited COA. Until then these show as pending, not as a benchmark presented as our number.
Test method: Internal burn test (stated conditions); proximate by ASTM D1762
For the composition figures behind heat and burn — fixed carbon, ash, calorific value — see the lab reports and test methods, and inspect the actual graded stock on the ready-stock board.
Questions
Mainly higher fixed carbon and higher density, with low moisture so energy isn't wasted as steam. Fixed carbon and moisture are measured by ASTM D1762 and calorific value by ASTM D5865 — so the drivers of heat and burn are checkable, not just claimed.
Because burn time depends on piece size, airflow, and the test setup, so a bare 'burns for X hours' is meaningless. We publish burn time and peak temperature only from our own burn test with the conditions stated, never copied from a benchmark.
Yes. Larger, denser hexagonal or pillow pieces sustain heat longer than small or loosely pressed ones, so burn time and surface temperature are shape-sensitive and are stated per shape with their test conditions.
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