Spin casting of mixtures of nonvolatile polymeric solutes dissolved in volatile solvents is studied experimentally and theoretically. The final solute coverage, time-resolved film thinning, time-resolved solvent evaporation, and evolution of the solute concentration within the thinning film is investigated for various combinations of different polymers (PMMA, PS, PS-b-PMMA) and different solvents (toluene, ethylacetate) for a wide range of polymer concentrations and spin cast conditions. The comprehensive data unveil a clear picture of the spin cast process. The findings are translated into a concise theoretical description. Easily available bulk properties of the solvent/solute mixture plus a single "calibration" experiment are sufficient for a quantitative description of the spin cast process including a prediction of the final solute coverage. This and the well-specified boundary conditions render the approach useful for practical applications. (C) 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.