Graphite oxide could be made a lot less flammable if a common contaminant were removed prior to use. Oxidizing and exfoliating graphite with concentrated acids and potent oxidizers such as potassium permanganate is well-known step in the production of the popular experimental material graphene. In contrast, graphene-type products made from graphite oxide - reduced graphite oxide and chemically modified graphene - are highly flame resistant. Now, while studying graphite oxide's exothermic properties, Northwestern University materials scientists Franklin Kim, Jiayan Luo, Jiaxing Huang, and colleagues have discovered that in the solid state, the material can undergo self-sustaining deoxygenation that propagates throughout the entire sample. Potassium salt residues are to blame the team has found.