What is the primary purpose of applying a tack coat?

The primary purpose of applying a tack coat is to prepare a surface for subsequent layers of paint or coating. A tack coat acts as an adhesive layer between the existing surface and the new application, ensuring good mechanical bonding. This is crucial in multi-coat systems, as it helps prevent delamination or peeling of the topcoat due to inadequate adhesion.

When a tack coat is applied, it creates a slightly sticky surface that helps subsequent layers bond effectively, improving the overall durability and performance of the coating system. This step is particularly important in environments where coatings are subjected to stresses, such as humidity and temperature fluctuations, as it provides a stronger foundation for the layers to come.

In contrast, other options like finishing the surface paint or enhancing color vibrancy do not reflect the primary function of a tack coat, which is not intended to serve aesthetic purposes directly. Similarly, reducing application time might not necessarily be a consequence of applying a tack coat, as the focus is on ensuring adequate adhesion rather than speed. Thus, option B distinctly highlights the primary role of a tack coat in coating systems.