Why are there black dots around a car window?
Frit band
Their presence of dots on a car window once began out of a very practical necessity: car windows, in fact, are fixed into the body with glue. That glue must adhere well and not be affected by sunlight. This is why you often see a black border (also called the frit band) along the window. The black dots are applied with a ceramic paint that is baked into the window during the manufacturing process. As a result, they do not wear off and are resistant to heat and cleaning agents
The dots also provide a gradual transition from that black border to the clear glass. It prevents you from seeing a hard dividing line, which is more visually pleasing and gives the interior a more finished look. So what started out as purely functional grew into a subtle piece of design.
Temperature differences under control
Another important reason for dotting has to do with the sun. Car windows heat up when the sun is on them, but glass expands when heated. An all-black edge would absorb much more heat than the clear portion of the window, creating stress differences. That could lead to cracking or distortion of the glass. The dots create a kind of temperature gradient: from black to transparent. They reduce the risk of thermal stresses and make the window last much longer without damage.
Sun protection
You may have noticed yourself that behind the dots the sun seems a little less bright. That’s right: the dots act as a kind of sunscreen. They filter light and heat, making the interior heat up less quickly. Especially near the interior mirror and rearview mirror, you often see a larger area of dots. That extra dark area prevents annoying reflections and glare from the sun.
How do you recognize variations?
Not every car has exactly the same dot patterns. In some models, the dots are larger or more densely spaced; in others, they form a flowing pattern. You also sometimes see creative variations, where manufacturers play with the pattern to give the windshield its own look. Think, for example, of dots that run toward a logo or a shadow area above the interior mirror that is executed slightly differently. Some brands are very creative: on many Jeep models, you sometimes see a black Jeep between the dots.
Also read: Never fogged up windows again? Here’s how you do it
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