What characteristic does a paint film need to have once it is dry?

A paint film, once dry, needs to produce a flexible and continuous layer to ensure durability and adhesion to the surface it covers. This characteristic is crucial as it allows the paint to expand and contract with changes in temperature and humidity, preventing cracking or chipping over time. A flexible film can accommodate the natural movements of the substrate without losing its integrity, thereby providing a long-lasting finish.

A glossy and thick film may not necessarily contribute to durability, as high gloss can sometimes lead to a brittle surface. An easy-to-peel film is undesirable because it indicates poor adhesion, which can lead to premature failure of the paint job. Similarly, a matte and brittle finish would not hold up well under stress, leading to issues such as cracking and peeling, which compromise the protective qualities of the paint. Thus, the ability to form a flexible and continuous layer is fundamental in achieving a successful paint film.