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The windshields are surrounded by small black dots, sometimes also around the central rearview mirror to place the toll badge. But what is their real use?
The days of single-glass (laminated) windshields at the beginning of the 20th century are long gone. Since the 1950s, they have been made of tempered glass. Since then, the windshield has become athermic, heated, a head-up display screen, a support for rearview mirrors, cameras and sensors of all kinds. However, it remains a fragile element subject to the constraints of the weather, gravel and the sun. The star of the day is undoubtedly its greatest enemy after the projections of various objects of varying sizes. And on this high-tech curved glass, there are small black dots.
Smooth transition
The primary function of the black dots is aesthetic. It provides a smooth transition between the black perimeter strip hiding the glue, the frit, and the rest of the windshield. The latter is glued with a strong and durable urethane adhesive. The dots are baked directly onto the glass. Beyond their smooth transition effect, these black dots also create a stronger connection between the glass, the glue and the car frame. In particular, they prevent the glass from being distorted by the sun’s rays, as they help disperse heat. Due to their black color, they also reduce the deterioration of the glue by UV rays.
For electronic toll collection
Those around the rearview mirror have another additional function. They can reduce the glare of the driver by the reflection of light. They are also there for aesthetics while providing a favorable area for the passage of waves through athermic windshields. This is why it is better to install the toll badge there for France, Spain, Italy, Portugal or Scandinavia for example.