Have you ever noticed a pattern of black dots along the top of your windshield? Have you wondered what the purpose of the dots is?

Maybe you assumed they were a way to help shade the sun a bit to keep from blinding the driver, and that’s certainly a major benefit of the black dots.

This is why this pattern of dots is often referred to as the third visor, since it is usually found in the center of the windshield, between the driver and passenger sun visors. However, there is also more to the story.

The black dots are actually ceramic paint and this paint along the edge of windshield actually helps seal the windshield into place. The pattern of black dots is called a frit.

The ceramic paint of the frit helps the sealant adhesive stick to the glass which helps keep it firmly affixed to the frame of the vehicle. A final thing the frit does is to help minimize distortion to the glass when it is heated and bent to shape into the slightly curved windshield.

Typically, heating glass causes it to expand and this can create a distortion effect known as lensing. This would potentially make it hard to see through. The frit helps to spread the sharp thermal gradient between the glass and the dots and this minimizes or masks the distortion.

In sum, the third visor frit is more than just a weird collection of dots; it serves three very important purposes.