Polishing car windscreens – micro scatches

My wife’s car seems to have acquired a lot of tiny scratches on the windscreen that make it very difficult to see through when it’s dark and wet.

I’ve tried cleaning/degreasing it inside and out, which helped a bit, but it’s not good enough.

I’ve seen a few kits and products for polishing, using drill-mounted buffing attachments but am wary of making it worse.

Anyone have any recommendations? I will check with insurance – I know we can have it repaired for free/not much if it gets chipped, but don’t think scratches are covered.

Yeah, I have the same, and was wondering similar (although I was wondering if it was something that could be done professionally, there’s no chance I’m having a go myself)

Halfords (and other brands) will do “intensive glass cutter” type products, it’s basically T-cut for glass and works reasonably well for getting decades of pock marking and scratches out.

A drill / grinder pad attachment would definitely make the process a bit quicker as it’s obviously a lot harder than paint.

Anyone have any recommendations? I will check with insurance – I know we can have it repaired for free/not much if it gets chipped, but don’t think scratches are covered.

Insurance won’t pay for wear and tear on the windscreen, only if it’s broken by an actual event.

I’ve tried it – not a massive success but I didn’t persevere for all that long

£100 excess on the windscreen bit of the insurance sorted mine out. Replaced and 12yr old windscreen and the difference was amazing! It was actually an accidental break though. Some long bits of wood that I was taking to the tip. Loaded up the night before and they settled during the night in a way that pushed the front of them up and cracked the screen from the inside.

I used Carpro Ceriglass with a rotary polisher to do this, i wouldn’t recommend it.

A) even after a long time polishing (1 hr+) , the microscratches* were not improved much in the way i wanted, they still catch the sun at this time of year

B) larger scratches were not improved at all

C) the polish is the worst I’ve ever used for splattering all over the place

D) the glass gets extremely hot

E) did i mention, it takes forever

* for reference, you can’t catch them with a fingernail, you just *just* about detect a slight texture change with the fingertips. I can’t be sure but I believe they were caused by the  wipers automatically starting after the car had been parked under a conifer for a few days

I have never seen DIY glass polishing end well*. Either polish splattered everywhere and no noticeable improvement or cracked glass from the heat of over polishing. Not sure if professional cleaners are any better, or that much cheaper than a new screen.

If you do find something that works, let me know as 2 of my cars would benefit.

*Headlights can be massively improved with simply car polish as long as you keep the buffer moving and don’t loiter in one area too long.

Here are the before and after photos for the sidelights/indicators. About 20 minutes work.

What if it were to ‘accidentaly’ get stone chiped?

For insurance, it needs to be accidently cracked. They won’t replace it for screen chips even if it is within the MOT fail area. They also get quite suspicious if they refuse a stone chip claim and you submit a claim for storm damaged* smashed screen a week later.

*hit by a neighbours trampoline. Fortunately I had a photo to prove it.

Insurance won’t pay for wear and tear on the windscreen, only if it’s broken by an actual event.

Definition of actual event ? .

I mean a brick hitting a window in your hand is an actual event.

What is the actual life expectancy of a windscreen? I mean the mileage, before it gets worn by the wipers so you get a haze or blur etc when its wet/dark? 100,000miles?

Glass is far too hard to remove marring. A pointless exercise.

Definition of actual event ? .

I mean a brick hitting a window in your hand is an actual event

I once saw a seagull fly into a windscreen carrying an axe wrapped in a towel. True story

No help to the op now but my approach to windscreen longevity is new wipers each autumn. Best money you’ll spend.

What is the actual life expectancy of a windscreen? I mean the mileage, before it gets worn by the wipers so you get a haze or blur etc when its wet/dark? 100,000miles?

How long is a piece of string, I guess.. dirty wiper blades with grity dirt/leafs and twigs on them would have the largest impact over time I guess.

Wipers are for clearing water, not for cleaning the glass, so wouldn’t wear the glass in any significant way, I wouldn’t think.

So if your windows look like this: hose them down and give the blades a wipe rather than relying on the wipers to clean the dirt, therefore scratching the glass.

once saw a seagull fly into a windscreen carrying an axe wrapped in a towel. True story

Strange I’ve seen a few of those in my time too.

Definitely just get it replaced on insurance – all you need is for a rock to fall off a pickup in front and crack the screen and pay the excess.

I try to not use the wipers and rely on Rain X. It is surprisingly good for rain, not so good for nasty salty gritty road spray.

not so good for nasty salty gritty road spray.

Thinking about it, winter road spray is probably the largest contributor to windscreen scratches over time…all that muck and rock salt kicked up at 70mph I imagine creates quite a good grinding paste, and you don’t have the option of not using your wipers to clear it.

I had deep scratches on my windscreen with no amount of polishing effective.

In the end, I paid £50 (you will pay more now) to get a guy to use the industrial glass polishing to grind / shave off a layer off the windscreen.

It needs to be expertly done or the windscreen will break if the pressure is applied too much during the polishing process and the heat generated from the polishing the windscreen.

When the polisher was at work, he basically shaved off a layer of the windscreen and constantly checking the temperate.  There was plenty of glass/plastic mixed shaved bits and it smelled like burning plastic.

Be prepared for a replacement windscreen in the event that it breaks during the polishing process.  I was prepared for that but just thought I gave the industrial polisher a try.

Also the polisher ensured the polish was even so the whole windscreen was polished./shaved off.

After that all fine and the wind screen is Not weaker.

Don’t forget ….. Aftermarket windscreens favoured by your insurance tend to be shite.

I’ve never had an after market one last more than a couple of years. Yet the original usually lasts 10.

Can’t always be that lucky with the original/unlucky with the new one surely……and the new ones always pick up minor scratches/marks easier.

Isn’t glass (especially toughened windscreen glass) too tough to polish? Genuine question tbf, as I’ve never heard of windscreen polishing.

The normal action of polishing as I understand it is to either heat/melt the surface enough to flow the irregularity out if its soft enough, as WCA polishing his side repeaters (which should be a polycarbonate of some kind). Or to remove enough of the surface as to ‘lift’ the fault from the area,  but this then leaves surface deformation that needs to be blended to look good.

Anything that can remove scratches from tough glass would either heat the glass so much as to discolour it or remove the surface so much the you’ll end up looking through the bottom of a pint glass.

I’ve polished a scratch out of a rear screen using cerium oxide polish. It didn’t heat the glass up much but I was doing it by hand.

I wouldn’t want to do a windscreen, I care far more about the visual accuracy looking forward.

Isn’t glass (especially toughened windscreen glass) too tough to polish? Genuine question tbf, as I’ve never heard of windscreen polishing.

Yes, I have never heard of them before I tried them. He was basically using a powerful grinder to shave the windscreen.

I was going to replace the windscreen using 2nd hand part but thought I would give that a try.

I don’t think it is glass but some sort of a mixed with glass, hence the plastic smell.

The guy was an expert and there was no uneven spot nor did he use any thing to “melt” the windscreen.

My car is just a Toyota Corolla 2005 with no fancy windscreen.  Therefore, nothing fancy that would go wrong except breakage.

I’ve tried Auto Finesse glass polish. Absolute garbage (like most of their other products to be fair).

After that all fine and the wind screen is Not weaker.

So someone shaved a layer off your car windscreen and its not weaker? OK…

Don’t forget ….. Aftermarket windscreens favoured by your insurance tend to be shite.

I’ve never had an after market one last more than a couple of years. Yet the original usually lasts 10.

Can’t always be that lucky with the original/unlucky with the new one surely……and the new ones always pick up minor scratches/marks easier.

Same here, OH’s fiesta got a new screen a couple of years back and it’s got a few big scratches already, including one somehow on the inside . It’s also a funny color, or maybe it just refracts light differently because I’m sure it sometimes looks blue and other days yellow, it’s definitely filtering out some wavelengths.

The heating elements on my old car and the work transit (which seemed to be particularly prone to chips and cracks) were more visible too,

So someone shaved a layer off your car windscreen and its not weaker? OK…

The strength comes from the fact it’s laminated over a plastic layer.  Polishing off a few microns won’t have a measurable impact.

fettlin

Full Member
Isn’t glass (especially toughened windscreen glass) too tough to polish? Genuine question tbf, as I’ve never heard of windscreen polishing.

The normal action of polishing as I understand it is to either heat/melt the surface enough to flow the irregularity out if its soft enough, as WCA polishing his side repeaters (which should be a polycarbonate of some kind). Or to remove enough of the surface as to ‘lift’ the fault from the area,  but this then leaves surface deformation that needs to be blended to look good.

Anything that can remove scratches from tough glass would either heat the glass so much as to discolour it or remove the surface so much the you’ll end up looking through the bottom of a pint glass.

The very lightest surface damage can be polished out, but it takes a lot of time and the correct polish/pad. Usually rayon pad with a polish with cerium oxide in it. As I mentioned, I used the CarPro Ceriglass kit to do mine, and it restored the ‘sparkle’ to the screen really nicely but didn’t remove even the most minor scratches.

I think any kind of scratching will mostly likely need a much more aggressive sanding, like the first few passes in the video, and as you say, I guess you’d have to blend it out a really long way to avoid distortion on a windscreen.

spoke to insurer (Admiral) and they will replace on the insurance, the excess is £115 so not too bad.

I’ve tried a few different cleaners to see if it’s some sort of surface contamination. The disc brake cleaner made it lovely and clear when it was dry – and no visible scratches – but as soon as it was wet, it was rubbish again. Going to try some rain repellent to see what that does. Maybe its a problem with an old coating or treatment?

@Lodger – insurance are replacing a (10 years worth) scratched windscreen for just the excess?

You didn’t have to make an accidental motorway mishap crack in it?

Wow…

Time to call my insurer and demand similar!…..

No. Was pretty easy. I said not chipped or cracked, just rubbish at night.

Autoglass dont have any drop down menus for that, but I rang them up and they booked it in for Monday. Wanted £40 extra for their rain repel coating, bit the bottles of it are only £8ish so thought I’d try that first

Wife insists whatever it is occurred when I borrowed the car to get to a job in Newport.  It did get very dusty (i was working in the port) but I didn’t use the wipers and went straight to a car wash and had it pressure washed before they wiped it. Just Newport corrosive environment i guess.

Wipers are for clearing water, not for cleaning the glass, so wouldn’t wear the glass in any significant way, I wouldn’t think.

No, they don’t, but

all that muck and rock salt kicked up at 70mph I imagine creates quite a good grinding paste, and you don’t have the option of not using your wipers to clear it.

is what does the damage – sand, which gets blown onto roads, as well as spread from trucks carrying it, is quartz, and is remarkably effective at scratching glass, which is made from quartz/sand.

Headlight lenses are mostly plastic, which is why they go cloudy and yellow, and they can be polished.

Having seen a remarkable number of car screens with cracks in while working in logistics, I asked an Autoglass fitter who was replacing a screen and re-calibrating the sensors and cameras about modern screens, and he confirmed my suspicions that modern screens are a fair bit thinner than a couple of decades ago, basically to save weight, and to cause less distortion to the sensors mounted on the back, which is why they crack for very little reason sometimes.

A replacement screen for my Ford is around £1000, because it’s heated – I make sure it’s covered under the insurance. A panoramic glass roof, which can be cracked when loading a roof rack or carrier, or even something dropping from a tree, that’s £12-1500. An LED headlight unit? About the same, £12-1500.

Personally, I ignore small marks on my screen, there’s one or two tiny chips, but they’re no more noticeable than the heating element in the glass, usually – very low level sunlight will show them up, but regular applications of RainX are the best thing.