Charcoal is a high-carbon microporous product produced by wood pyrolysis in the absence of oxygen.
The weight of 1 m3 of charcoal is up to 176 kg for birch, 180 kg for oak, 138 kg for aspen, and 120 kg for spruce.
Charcoal is generally produced from softwood or hardwood (which is preferable).
Charcoal lumps come in two sizes: small lumps of 6–12 mm, and large lumps of over 25 mm.
Charcoal is available in two grades: Premium grade А and First grade B.
Charcoal production is deemed to be easy, however, it requires certain skills and knowledge, otherwise it may affect the product quality and lower the yield.
Phases of charcoal making process:

• Drying (to remove moisture from wood as moist wood does not burn well)
• Pyrolysis (the key process when the wood is burned in the absence of oxygen)
• Heating (to remove excessive gases and resins)
• Cooling.

Quality charcoal has a glossy black colour with blue highlights and preserves the grain of the wood.
It has a cracked surface, and such cracks speak for the time of carbonization (the more cracks, the faster was the carbonization).
When shaken, charcoal lumps make a tinkling sound. The charcoal gets alight easily and gives good heat.