What about those black dots on your windshield?
You most probably noticed a pattern of little black dots on the edges of a car or bus windows but did not give much thought as to why are these there. It’s all about the frit! That baked-in ceramic painted band around the edge of the glass which is almost impossible to scrape off. It is not just there as a little design quirk – the frit actually serves to 2 very specific purposes.
First, it acts as a shield against ultraviolet sun rays, which prevents it from deteriorating the sealant on the windshield, because nobody wants the sun to cook the adhesive and send the window flying out next time we hit a bump. Second, it covers up the glue on the edge of the windshield. The dots, on the other hand, are there for an aesthetic reason, as they form a nice gradient between the frit and the rest of the windshield.