Spin-assembly is an excellent method for controlling the amount and thickness of adsorbed polyelectrolyte in fabricating multilayer thin films. These films are investigated by means of ellipsometry and UV-vis spectroscopy and their spectral properties are used to determine the effect of the polyelectrolyte concentration, the speed of rotation, and other experimental parameters on the film thickness and uniformity. Adjusting these parameters allows fine-tuning of the multilayer thin films and provides the spin-assembly method with a control tool for many future applications.