At some full stop on a long cause , you or a persistent baby have probably marvel what the contraband dot at the top of yourwindscreen are for .

They appear to be on most vehicles but , like indicators , almost nobody knows what they are for . You might guess that the blackened " frit " stretching across the windshield is cosmetic , or to keep a slight light out . But in fact the strip is there to keep the windshield in place and allow you to see properly , but in all probability not in the way you ’d gestate .

Before the fifties and 60 , windscreens were held in place with ametal trimming , before manufacturers moved to using adhesives . Frits , made of a rough ceramic paint , are there to conceal this unworthy adhesive ; but also to aid keep the windshield in piazza .

“ The modern windshield is a marvel of engineering , and defy we say one of the most underappreciated components of a vehicle . Part of that engineering affect how the windshield is tie to the human body , ” ablog postfrom North Carolina - based bodyshop DeDona Tint & Sound explains .

“ While the inward front side of the frit allow adhesive to adhere to the crank , the outbound present side of the frit pretend as a shield against ultraviolet light radiation for protect the adhesive bond , which would otherwise be weakened by continual exposure to direct sunlight . ”

As well as protect the adhesive adhesion from ultraviolet radiation , ultimately hold on your windscreen from wing at you mid - drive , the back breaker gradient running aside from the frit serves another important purpose . During manufacture , an engineer with Pittsburgh Glass Works explain toJalopnik , windscreens are bent inside a hot oven .

While inside the oven , the longsighted black frit heats up faster than the deoxyephedrine of the windshield . go away alone , without the superman ground substance , this would innovate distortions into the meth . But the dot leading aside from the black frit help circularise the temperature more evenly , helping to reduce any distortion , which would n’t be ideal while you’redriving .

The frit is also supposed to look pleasing , which is good because as it is baked onto the windscreen , it is virtually impossible to scrape off .