Which ingredient in paint is responsible for forming a solid film after drying?

Binders are the key ingredient in paint responsible for forming a solid film after drying. Their primary function is to hold the pigment particles together and provide adhesion to the surface being painted. As the paint dries, the solvent evaporates, causing the binder to coalesce and form a continuous, solid film. This film is essential for protecting the substrate, providing durability, and contributing to the overall finish of the paint.

In contrast, solvents are used to dissolve and carry the other components of the paint, facilitating application. They evaporate during the drying process and do not contribute to the film formation. Surfactants serve to reduce the surface tension of the paint, enhancing its application properties and stability but do not contribute to the solid film. Fillers are added to improve texture and opacity but also do not function as the primary film-forming component. Thus, binders play a crucial role in creating a durable and protective layer once the paint has dried.