What is the primary purpose of the frit band on a windshield?

The primary purpose of the frit band on a windshield is to improve surface adhesion. The frit band comprises a ceramic paint that is baked into the glass during manufacturing. This band provides roughness on the glass surface, which enhances the bonding of adhesives used during windshield installation. A better adhesive bond is critical for ensuring the structural integrity of the windshield, especially in the event of a collision, as it helps keep the windshield in place.

While the frit band may have some secondary benefits, such as providing a barrier for UV light, its main function is firmly tied to improving how well the windshield adheres to the vehicle's frame, thereby contributing to safety and performance. The reasons related to aesthetics and UV protection are not its primary function but rather aspects that are either incidental or secondary in nature.