**6.1 Solvent evaporation**

The most typical approach for preparing thin films utilising water-soluble excipients, polymers, and drugs that are dissolved in de-ionised water is solvent evaporation; as a result, a homogeneous mixture is formed by applying high shear forces generated by a shear processor. To get good quality films, the prepared solution is placed onto a Petri plate and the solvent is allowed to dry by exposing it to high temperatures. The film-forming polymer is normally immersed in a suitable solvent overnight in the solvent casting procedure. The type of API that must be included in the film determines the appropriate solvent based on essential physicochemical parameters of the API such as melting temperature, shear sensitivity, and polymorphic form. Before completing a formulation, the drug's compatibility with the solvent and other excipients is taken into account. Entrapment of air bubbles during formulation might affect the homogeneity of produced films. **Figures 2** and **3** indicating the deaeration of the mixture is therefore accomplished with the aid of a vacuum pump [45].
