The goal of this study is to unveil the behavior of fiber finishes during textile processing and use. Specifically, we investigate the structure of adsorbed layers and the thermodynamics of interactions between typical finish components and nonwoven substrates. We are using polymeric surfaces produced by spin coating as models for fibers consisting of PP, PE, Nylon, cellulose and PET. The nature of the finishes, their surfactant and lubricant components and the films they produce are studied by using QCM, AFM, XPS and DCA. The extent of adsorption, as well as the dynamics of the process (adsorption and desorption) and the topography of the produced film are related to the chemical nature of the additives and the substrate. The results are used to explain the stability of organic films before and after drying and the relationship with their functional properties. Finally, our observations are used to address the case of fiber applications in textile industries.