FireCarb is based on a high quality Chinese crystalline flake graphite, it's structure is in the form of layered sheets of carbon atoms. In a process known as intercalation, an acid solution is placed between the carbon layers. Following manufacture, the material is thoroughly washed and dried trapping the solutions within the platelets. The end result is a dry, pourable, clean material with minimal surface acidity.
Expandable graphite belongs to a group of products called 'intumescents'; the main property of which is the ability to expand when heated. On exposure to heat the retained solutions within FireCarb produce a gas that expands and forces open the graphite platelets.
The tremendous expansion that expandable graphite offers (up to 350 x volume at 1000°C) makes it more effective than conventional intumescents. This expansion has the added benefit of creating high pressure, especially when mechanically restricted. At the same time an insulating carbonaceous char is formed which protects the substructure from the heat source.
Typically expansion starts at 170°C, and standard FireCarb grades demonstrate both a good onset of expansion at relatively low temperature and a high total volume of expansion.