The main phase transition from the fluid state of low density to the condensed state is studied in tetradecanol monolayers using Brewster angle microscopy. The condensed phase patterns obtained on a water subphase and on sodium dodecyl sulphate (SDS) solutions are compared. The addition of SDS to the bulk phase lowers the line tension and changes the circular shape of the equilibrium condensed phase domains evolved on the water subphase. As a consequence, non-equilibrium fingering patterns are formed during compression on aqueous SDS solutions. The patterns relax slowly to equilibrium structures to minimize the total free energy.