The first part of this investigation focused on the synthesis and characterization of a new type of intumescent flame-retardant (IFR) agent. Four steps were used in the synthesis process. The structure was characterized by FTIR, magic-angle spinning nuclear magnetic resonance (MAS-NMR) C-13 spectroscopy, and elemental analysis. The addition of an IFR agent into polyurethane (PU) varnish led to an improvement in its carbonization and flame-retardant (FR) properties. The second part focused on the evaluation of such characteristics as FR property, thermal stability of IFR/PU-based coatings, rheology of IFR/PU-based coating solutions, and mechanical properties such as hardness, adhesion, and flexibility of IFR/PU-based dry coating films. (C) 2003 Wiley Periodicals, Inc.