Different macroscopic structures in poly(gamma-benzyl-L-glutamate) (PBLG) films were prepared by spin coating using different preparation methods. These structures were analysed between two polarizers or using polarization microscopy. The main parameters for creating structures during the spin coating process have been determined. In particular, the influence of coriolis forces during the spin coating process and solution properties were studied and resulted in a proposal for the mechanism of the production of structures.