Analytical and experimental studies of surface tension and viscosity properties of Dow resins PS-2 and 276V-2 are described. This investigation was undertaken to provide information on materials of interest for thermoplastic recording. It was found that external plasticization lowered the surface tension of the polystyrene while greatly decreasing the viscosity. Typical values for a 25% mixture of PS-2 in 276V-2 are γ = 35 dynes/cm. and η = 20 poise at 80°C.