This paper deals with the influences that mineral oil, resin and polymer concentrations, and temperature, exert on the steady-state viscous how of model synthetic binders. With this aim, both binary (oil/resin and oil/polymer) and ternary systems have been studied. All the systems show a Newtonian region in a shear rate range that depends on binder concentration and temperature. The temperature dependence of the zero-shear-rate-limiting viscosity is described by an Arrhenius-like equation, in a temperature range that depends on binder composition. This limiting viscosity, at any concentration and temperature within the experimental range studied, can be estimated from the values of activation energies and viscosities of the binary oil/resin systems and the polymer concentration used. These results have been discussed on the basis of the development, depending on the polymer/resin ratio, of both a polymer-rich phase and a resin-rich phase in the bulk binder and its influence on the microstructure of the system. (C) 2001 Elsevier Science Ltd. All rights reserved.