Contaminated Windscreen

daniel_ley

Active Member
Mar 3, 2018
97
35
Dudley
Hi all. Has anyone had any experience with having a contaminated windscreen, and how to resolve it?

I've got a 2020 FR Black Edition and the windscreen is just terrible in the cold or wet. I'm not sure if it's something I'm cleaning the vehicle with, or whether it was something that happened to the vehicle before it was delivered as it was delayed significantly due to COVID so was sat in a compound somewhere for a few months.

I'm assuming it's some sort of wax/grease deposit, or maybe even sap? As soon as it's cold the outside of the screen condenses really easily and is difficult to see through. Using the wipers doesn't help much, assuming that they're also contaminated too with whatever it is?

I made a hash effort to use white vinegar spray and then washing up liquid which were some recommendations I found, my next effort will be sugarsoap which I read elsewhere could help. I basically haven't really got a clue what I'm doing though having never experienced something this bad before. Do I need to try and use a clay bar on it?

The photos below were taken on a day where I'd cleaned the car, so the windscreen wasn't actuality dirty, but this is what appears when I first set off on a journey. As soon as the screen has heated up it dissapears.

Screenshot 2020-11-08 at 20.49.13.png


Screenshot 2020-11-08 at 20.49.27.png


Cheers!
 

Mr Pig

Active Member
Jun 17, 2015
2,614
906
I've had this before but not on such a new car. Changing the wiper blades has by far been the biggest factor. Valeo ones are my go-to these days and I rarely get a problem.

Have you cleaned the inside? I found that most of the special cleaning products actually make the screen worse! They leave a waxy film on the screen that fogs up as soon as the wipers drag across it. An alcohol based cleaner that doesn't leave any residue is all I'd use but if you use decent blades even that shouldn't be necessary. On such a new car I'd be surprised if you can't get it cleaned. My bet is the idiot valeter at the dealer has put polish on the windscreen.
 

daniel_ley

Active Member
Mar 3, 2018
97
35
Dudley
I've had this before but not on such a new car. Changing the wiper blades has by far been the biggest factor. Valeo ones are my go-to these days and I rarely get a problem.

Have you cleaned the inside? I found that most of the special cleaning products actually make the screen worse! They leave a waxy film on the screen that fogs up as soon as the wipers drag across it. An alcohol based cleaner that doesn't leave any residue is all I'd use but if you use decent blades even that shouldn't be necessary. On such a new car I'd be surprised if you can't get it cleaned. My bet is the idiot valeter at the dealer has put polish on the windscreen.

I've ordered some new blades already, just seems mad that I'm already having to buy them for a brand new car but I figured that was a good place to start. I don't want to fit them though until I've made a few more attempts at clearing whatever is on the screen as I assume I'll just ruin the new blades too. The inside has been cleaned too. I'll try changing my glass cleaner for something different too and perhaps try and alcohol based one. It's just a minefield reading online about how to sort it!
 

DEAN0

Old Git
Feb 1, 2006
5,288
300
Preston - UK
Before you fit the new blades - try cleaning the screen with IPA ( isopropyl alcohol ) - it's reasonably cheap and seems to shift most crap off the screen without attacking the rubber or paint if it gets on them.
 
  • Like
Reactions: Woody_72

daniel_ley

Active Member
Mar 3, 2018
97
35
Dudley
Before you fit the new blades - try cleaning the screen with IPA ( isopropyl alcohol ) - it's reasonably cheap and seems to shift most crap off the screen without attacking the rubber or paint if it gets on them.

Thank you. Will try this too. Will keep the wipers safe in their box until I'm certain I've made all efforts to try and clean the screen first!
 

Mr Pig

Active Member
Jun 17, 2015
2,614
906
IPA is good because it does not leave any residue at all and will cut through a lot of things. Rubbing Alcohol is basically the same thing and might be easier to find. You want to change the blades at the same time as crap blades will smear even on a perfectly clean screen.

The brand of blade matters. Years ago I was getting persistent issues, bought new blades and it would be better for a short time then the problem came back. I even got a new windscreen fitted and still had issues. Changed to Valeo blades and I've not had a problem since other than the blades shuddering when they wear out but they'll all do that eventually.
 

daniel_ley

Active Member
Mar 3, 2018
97
35
Dudley
IPA is good because it does not leave any residue at all and will cut through a lot of things. Rubbing Alcohol is basically the same thing and might be easier to find. You want to change the blades at the same time as crap blades will smear even on a perfectly clean screen.

The brand of blade matters. Years ago I was getting persistent issues, bought new blades and it would be better for a short time then the problem came back. I even got a new windscreen fitted and still had issues. Changed to Valeo blades and I've not had a problem since other than the blades shuddering when they wear out but they'll all do that eventually.

Cheers, yeah the ones I've ordered are Valeo as I remember always seeing them as a recommendation on here! Will give IPA a good go then with some elbow grease and see how I get on.
 

Mr Pig

Active Member
Jun 17, 2015
2,614
906
I think Valeo are what Seat fit out of the box, maybe.

I find that immediately after you clean the screen and fit new blades it might still smear a bit for awhile but it will clean up.
 
Sep 28, 2020
22
0
Bar keepers friend mixed with white vinegar to a paste. Work in with a microfiber cloth then let it dry and buff off. Works a treat on many things that contaminate glass
 

3D_Rob

Active Member
Dec 20, 2019
11
4
Hampshire
I'm assuming it's some sort of wax/grease deposit, or maybe even sap? As soon as it's cold the outside of the screen condenses really easily and is difficult to see through. Using the wipers doesn't help much, assuming that they're also contaminated too with whatever it is?

I made a hash effort to use white vinegar spray and then washing up liquid which were some recommendations I found, my next effort will be sugarsoap which I read elsewhere could help. I basically haven't really got a clue what I'm doing though having never experienced something this bad before. Do I need to try and use a clay bar on it?
It's probably not sap since most sap is actually water soluble and washes off easily. I'd guess some type of paint sealant or wax residue that managed to bond to the glass. Some of the modern ones in particular are known for being very durable and chemical-resistant (which means hard to remove also).

But regardless of what it is, you need to use some proper car cleaning products rather than washing up liquid, white vinegar etc. I'd recommend Autogylm Car Glass Polish for a start. It contains mild abrasives and should cut through most residues that don't come off with normal washing. Best applied using some kind of sponge applicator pad and, since the abrasive is quite mild, you really need to use some pressure and possibly repeat applications.

If that doesn't work you might need to step up to something more aggressive. Just do your research before jumping in with the clay bar, they tend to get treated quite casually for how aggressive they are on paint. Though in fairness, glass is harder than paint and shouldn't scratch easily.

Incidentally, one of the best things I've done to my windscreen is applying two coats of Angelwax H2GO, an excellent rain repellent. Water just beads off and the screen is very easy to clean. Seems to last several months as well.
 

SRGTD

Active Member
May 26, 2014
2,388
1,279
@daniel_ley; I’d try rubbing alcohol first and if that doesn’t work, I’d try a clay bar. If you have any concerns over a clay bar being too aggressive to use on your windscreen, a fine clay bar is the least aggressive type of clay bar and should be OK. I’d avoid using a medium or heavy grade clay bar on car glass though.

If you do resort to using a clay bar, use one where water (warm water in a hand sprayer) can be used as a lubricant. Once the screen has been clayed and dried, follow up by cleaning it with proprietary car glass cleaning product.

Before fitting your new wiper blades, you may want to try cleaning the existing ones as they shouldn’t be worn out on a 2020 car. You could try neat screen wash (avoid getting it on your paintwork) on a clean cloth. Wipe each blade along its length a few times and dry. Follow up by cleaning the blades with rubbing alcohol.
 
Genuine SEAT Parts and Accessories.