Expandable graphite is a form of flake graphite infused with acid molecules inserted between its layered structure. When heated, the intercalated acid vaporizes, causing the graphite layers to rapidly separate. This results in dramatic volumetric expansion—up to 300 times or more—as the layers are forced apart. This unique property makes it invaluable for fire safety applications. When embedded in resins or sealants, expandable graphite responds to fire-induced heat by expanding, forming a protective char layer that blocks flames and smoke. Additionally, expanded graphite is halogen-free and environmentally sustainable, aligning with modern green material standards.