Why are the black strips and dots around car windscreens so vital to our safety… find out what they do here

Have you ever noticed the black strip and dots running around the edge of your car’s windscreen? Well, it turns out this pairing just happens to be a vital safety feature that your car really can’t do without.

So what are these dots all about? Read on

So what are these dots all about? Read on

Here we reveal the secrets behind the humble black strip and dots on our motors’ screens – and just why we really do rely on them for our safety while on the roads.

What are the black strip and ‘dots’ you’re talking about?

We’ll all have seen them, but it’s likely our mental processes decided the innocuous strip and dots simply weren’t worth committing to memory. However, take a look at the edge of your screen and you’ll see exactly what we’re talking about.

Oh yes – we know what you mean – but what are they for?

Okay, let us explain what the strip and dots are for. Here’s all you need to know.

The black strip – aka the ‘frit’

This is your windscreen - but do you know what the back strip and dots are for? You'll be surprised.

This is your windscreen – but do you know what the back strip and dots are for? You’ll be surprised.

A black band around the windscreen, the ‘frit’ is a ceramic paint that’s been baked into the glass – making it integral to the screen and impossible to scratch or scrape off.

Talking to jalopnik.com, UK-based auto glass manufacturer, Pilkington, described the purpose of the ‘frit’.

According to the glass firm, the strip has three main jobs. Most important of these is its ability to act as a filter to prevent damaging UV rays  attacking the sealant that holds the glass in place.

Without this protection, the sealant would deteriorate, allowing water to creep in and damage your motor – and possibly result in the windscreen becoming detached from the car. Not to be recommended!

Without this protection, a speed hump or pothole could send the screen flying to a shattering end!

What other uses does the ‘frit’ band have?

Along with the small matter of keeping your screen in place, Pilkington revealed it offers a rougher surface to the smooth glass – which helps the adhesive do its job attaching the shield to your car.

It also helps to improve the aesthetics of your car, by hiding the glue ‘splurged’ beneath the glass.

Okay, that makes sense, but what about the strange black dots?

Here’s what those strange black dots are really doing on your screen

The dots are a smart way to bridge the gap between the practical applications of the ‘frit’ and making our motors look pleasing to the eye.

The dots reduce in size as they encroach onto the screen, creating what appears to be a smooth gradient. This ensures the ‘frit’ does not leave a harsh black border to the windscreen.

Anything else on the black dots?

Yes – along with the simulated gradient, the dots also have a more practical use to aid drivers. According to Jalopnik.com, because screens are curved in a hot oven, the black ‘frit’ band heats up faster than the rest of the glass – which can cause some visual distortion at the edge of the screen.

To counter this, faded dots are used to ensure a more even temperature distribution during ‘baking’ to minimise and hide the distortion that could prove distracting for drivers.

Fine – but why has my car got a large spattering of dots around the rear-view mirror?

Simple! Many modern cars have this ‘third visor frit’ to block the sun in the gap between the two sun visors. This helps the driver get a clear view in the mirror without being blinded by the sun.

So, that’s why the black strip and dots are so vital for safety while we’re on the road.


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