Polyurethane coatings are highly flammable, and because of their widespread applications on different Substrates (wood, steel, and building materials), there is a need to increase their fire-safety properties. Intumescent additives sharply suppress the flammability properties Of polyurethane coatings. Two problems accompany intumescent additives: their high loading percentage and incompatibility With polyurethane coatings. In this research, we Succeeded hi increasing the compatibility by mixing intumescent additives with a butyl acrylate polymer and in lowering the flame-retardant additive loading (up to 20%) by incorporating newly modified montmorillonite. The flammability properties of the new intumescent coatings were characterized with a cone calorimeter. (C) 2008 Wiley Periodicals, Inc.