The black dots on your windshield are called “frits.” Frits are applied at the windshield factory as a black enamel band that is baked onto the edges of the glass. The solid black band gradually turns into a border of frit dots.
Windshield black dots (frits) do four things:
1) Help windshield adhesive bond to the glass
2) Protect the windshield adhesive damaging from UV rays
3) Help distribute glass temperature to prevent distortion
4) Provide a “3rd visor” for drivers
Fritting promotes windshield bonding
Because the black enamel coating is backed onto the glass at the factory, it acts as etching primer, allowing the urethane windshield adhesive to gain a better bond with the glass.
Fritting prevents adhesive degradation and failure
Windshield fritting acts as a UV barrier to prevent the sun’s rays from softening, melting and degrading the urethane adhesive.
Windshield fritting prevents optical distortion
The solid band of black enamel heats up faster than the graduated dot bands around the glass. Without the graduated band of dots, the black portions could cause the glass to distort, called “lensing,” that makes straight lines look curved. So the dots gradually dissipate the heat to prevent lensing from occurring.
Fritting eliminated the sharp edge look and acts as a 3rd visor
If the windshield didn’t have the frit border, the solid bland band wouldn’t look pleasing. In late model vehicles, carmakers add more fritting dots around the rear view mirror to provide an additional visor for an area typical visors can’t reach.
