A PROCESS FOR PREPARING A STABLE SPINNING COMPOSITION COMPRISING AN ACRYLONITRILE POLYMER DISSOLVED IN A CONCENTRATED INORGANIC SOLVENT SOLUTION THEREFOR AND A SURFACE ACTIVE AGENT INSOLUBLE IN SAID SOLUTION IS DISCOLSED WHICH COMPRISES DISPERSING SAID SURFACE ACTIVE AGENT IN SAID SOLUTION, MAINTAINING SAID DISPERSION AS A FILM UNDER RETION, AND DEFOAMING SAID DISPERSION AS A FILM UNDER REDUCED PRESSURE AT A TEMPERATURE WHICH IS AT LEAST EQUAL TO THE BOILING POINT OF SAID COMPOSITION AT THE REDUCED PRESSURE EMPLOYED.