I was flying a couple of times this week and got a window seat on the flight. When gazing out at the world below I noticed something similar I had to work on for a project some time back. Ever wondered why you see a black coating around the edges of plane windows or even on car windshields? The interesting part is not the black border, but the series of black dots around its periphery. It’s a little-known fact I thought I’d share with you all.
These black dots, are known as the “frits”. The frit is a ceramic/enamel paint that is baked into the glass edges at high temperatures. It’s incredibly tough and cannot be scraped off or damaged by UV rays. The black band in the frit helps the windshield glass stick to the window frame and hides the black adhesive used to stick the glass panel. It protects the adhesive from UV exposure and makes the adhesive last longer.
Now why do you need a black dot matrix all around it? You might also notice that the dots become less dense as they move inwards. It’s just a clever mechanism to distribute heat evenly from the edges while the glass is bent into shape. Less dense means, a smoother temperature gradient and you won’t have a sharp edge for the temperature gradient for the glass to crack at that edge. Dots are just a way to keep that gradient. Remember more black color always absorbs more heat.
So, the next time you see those black dots, you’ll know they’re not just for decoration. Tiny engineering details make all the difference!
