Why do car windscreens have those tiny black dots?

Most car windscreens have tiny black dots of various sizes along their edges. We can find them in vehicles of every class, from different manufacturers. What is their actual purpose?

Although they may seem insignificant, they serve an essential function. To understand their significance, we need to look at the process of installing windscreens in cars. Before the glass panel is mounted, its edges are coated with ceramic paint and heated. This process ensures that the adhesive adheres better to the rough surface.

During heating, the paint reaches a higher temperature than the glass itself. These dots protect the windscreen from cracking due to temperature differences, which reduces the temperature difference on a tiny glass surface. The size of the dots changes gradually to protect the windshield effectively.

Additionally, the black frame of the windscreen, known as the "frit", masks the adhesive used to install the windshield. It also protects it from harmful UV radiation, which helps to extend its lifespan.