An intumescent material includes a liquid carrier with a corrosion inhibitor, such as a coating forming material, expandable particulate graphite (flake graphite or lump graphite) and if desired a filler. The intumescent material has a pH greater than 7.0, to reduce the corrosive properties of the intumescent material for most metals used in the construction industry and to provide a chemical environment conducive to the forming of a corrosion inhibiting layer by the corrosion inhibitor. The method of making the intumescent material includes combining the liquid carrier, the corrosion inhibitor, the expandable particulate graphite, the filler (if used), and a pH enhancer (if necessary to bring the intumescent material within the desired pH range), to form an intumescent material having a pH greater than 7.0.