What defines a tack coat in the context of paint application?

A tack coat is specifically defined as a thin layer of paint or coating applied to a surface to promote better adhesion of subsequent layers. The purpose of a tack coat is to provide a slight degree of stickiness, ensuring that the next coat adheres effectively to the surface, thereby improving overall coating performance and durability.

In this context, a tack coat is essential for ensuring that the layers bond properly and perform as intended, thereby preventing issues such as delamination or peeling. This is particularly important in multi-coat applications, where the integrity and longevity of the final finish can be significantly affected by the quality of adhesion between each layer.

The other choices do not accurately describe a tack coat. A fully cured primer pertains to a different aspect of surface preparation; a top coat is typically the final layer intended for protection; and a coat applied before an anti-fouling layer does not capture the primary purpose of a tack coat, which is enhancing adhesion between layers rather than serving a specific function before a certain type of coating.