Many car owners wonder what the black dots on their car windows are for. You are not alone. In this mobility piece, we look at the purpose of the dots, and you will then know their use going forward. It’s highly possible that you see them every day even if you don’t have a car. In motoring terms, they are called frits.
The definition of black dots on your car window
Motoring publications have always published all the parts and purposes of some of what we may see as decorations. Today we give you more on these dots. They are intriguing because they seem to be present in almost all cars today, but these black dots are so underrated.
According to Autoglaze, these dots are known as frits. What is a frit? It is a painted black enamel that’s baked around the borders of a windscreen during the manufacturing process.
In almost every car, these dots often start as solid black bands near the edge, gradually dissolving into small dots at the outer edge. They are seen on windscreens and other parts of your car’s glass windows and we have picked up four of their main purposes.
The purpose of black dots on your windscreen
The dots also known as frits serve an important purpose such as working as a contact point between the glass and car frame. The dots create “etches” on the surface, making them rougher so the adhesive can stick better to the glass.
In checking out their second purpose, the dots help drivers to sustain the urethane sealant used to bond the glass to the frame of your car. In most cases, they use the black enamel outside the windshield to block the sun’s ultraviolet rays from melting the adhesive underneath the band. In essence, they keep the windows firmly glued in their place.
Looking at the purpose of the black dots also referred to as the “dot matrix”, they help distribute temperature evenly to lessen optical distortion or “lensing”.
“This happens when the frit band (the solid black one) heats up much faster than the windscreen’s glass, creating an optical distortion that makes either straight lines look curved or bowed inwards toward the centre,” reports Autoglaze.
“Those “gradually sinking” black dots help lessen this phenomenon by dissipating the heat and spreading it out evenly.”
Moreover, frits are also there for aesthetic purposes and if you pay attention, the contrast between the dark band and the transparent glass can look too obvious even when viewed from afar. Creating a halftone pattern or “dot-matrix” allows a gradual decrease in size, making the transition much more subtle and easier on the eyes.
The car publication also posted that frits have been slowly evolving over the past few years. In modern cars, these dots add “third visor frits” right behind the rear-view mirror to block the sun between two sun visors.
What happens if there are no black dots
In a recent special feature, Slashgear.com explains the purpose of black dots. They report that “if a glass sheet simply had a plain band of UV-absorbing enamel, it would get hotter while the rest of the region would be at a lower temperature under sunlight.”
In a simple explanation, there is a sharp separation between hot and cold glass on the same surface. That’s not a good sign, “as it could lead to deformation and become prone to damage over time”.
Hot glass can also create an optical distortion effect, which is also referred to as lensing and that explains the purpose of the black dots in your car window.