Drivers only just realising what black dots on car windscreen are for

People are only just realising what the black dots on a car windscreen are for - and just how important they are. Black dots on the windscreen are called frits - and there are vital for safety - according to road users and motoring experts.

The frit band is enamel that is baked into the borders of the windscreen, parts of the windows and sometimes behind the rear-view mirror during the manufacturing process. Usually the frit band starts as a solid line before morphing into lots of individual small dots nearer the edge.

They serve as a contact point between the glass and car frame. They create “etches” on the surface, making them rougher so the adhesive can stick better to the glass. They help preserve the urethane sealant used to bond the glass to the frame.

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They use the black enamel outside the windshield to block the sun’s ultraviolet rays from melting the adhesive underneath the band. This keeps the windows firmly glued in their place. On social media, one driver questioned: "I don't see how the frits could "wear away",unless the operator was scraping at them with something,or using harsh window cleaners. and "replacing the frits" means replacing the window glass,because the frits are printed ON the glass."

"A more useful set of dots to an owner/mechanic are the small groups of 3 where the parked windscreen wiper should be aligned with anytime the arm is removed," another said. Autoglaze explained: "The black dots, or “dot matrix” actually 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.

"Those “gradually sinking” black dots help lessen this phenomenon by dissipating the heat and spreading it out evenly."