Insurance Questions: Windscreen Cover

Can I get my insurer to pay for this?

Most comprehensive insurance policies will include windscreen cover as standard. As straight forward as this may appear, there are some grey areas, some of which has been misinterpreted or misunderstood, to cause confusion amongst the insured.

Direct Vision through Windscreen

Direct Vision through Windscreen

Here are some of the most common questions asked on Internet forums; but first, it should be noted that the onus is very much on policyholder to tell the truth. The repairer’s role is a position of trust and one which requires him or her to make an assessment on behalf of the insurer/underwriter (as well as to present the policyholder the correct diagnosis). Honesty is always the best policy, but there are a few areas which are open to abuse.

“I bought a car which had a cracked windscreen,” or that the car had a chipped windscreen which has previously been repaired badly.

This is probably the most asked question, and almost definitely the one which shows the most ignorance and dishonesty among those who discuss it. The reality is, the damage occurred before (current) policy inception. It is not a loss the insurer is obliged to indemnify. The problem with this situation is that the insurer relies on the honesty of the policyholder, and the integrity of the repairer but there is no way of verifying the cause (and date) of the reported damage.

“My windscreen is scratched. Am I covered?”

A tricky one and very much subjective. How an insurer – or the insurance policy – interprets damage is how this one will be defined. Policy wording seldom identifies scratched glass as damage, although it could be argued that graffiti is vandalism but this may not be covered under the windscreen insurance end of the policy (some insurers have paid out for this under general insurance which will carry a higher excess and will impact the policyholder’s NCD). The only way to ascertain if wiper scratches or general scratches (such as from clearing ice or dirt from the windscreen) are covered by an insurer is to check the policy Key Facts or speak to the insurer. The problem this presents is that the ‘glassline’ number will usually be pointed straight at the prevailing repairer whose role is to make an honest and correct assessment on behalf of the insurer it is representing.

Pitted Windscreen 2

Pitted Windscreen

Pitted Glass

“There is surface pitting on my windscreen. When I’m driving into direct sunlight, or oncoming headlamps, I can’t see through the glass. It’s like the windscreen has been shot blasted and is covered with millions of tiny chips about the size of a pin head.”

First and foremost, the windscreen is a forward facing piece of glass in a vehicle. In other words, the driver’s direct view of the road is reliant on the windscreen being in good condition, or being fit for purpose. For vehicle to be legally roadworthy, the MOT Testers Manual states that a reason for rejection is:

“a combination of minor damage areas which seriously restricts the driver’s view in the remainder of the [wiper] swept area”

With this in mind, does this correlate and fit into what the insurer will construe as damage, or an indemnifiable loss? Some insurers will allow some discretion whilst others may not be so accommodating.  Most pertinent to note is that this is all open to interpretation whichever way you were to look at it and the system (in the absence of a better noun) is open to abuse by all parties.

“Will claiming on my insurance impact my NCD?”

Probably the most enigmatic and undefined areas of windscreen insurance is what subsequent impact a claim will have on any future insurance. The majority of policies will state that there will be no impact on NCD following a windscreen claim, however, some policies clearly do. Furthermore, there is no definitive statement from any insurer whether – regardless of how NCD may or may not be affected – the premium will be increased on renewal. Is there a claw-back somewhere? The nature of the business suggests there might be; is it a factor in the rising cost of motor insurance? There is no official word on this and insurance industry representatives remain reticent.

Windscreen Replacement

Windscreen Replacement

Have you had one of these windscreen claim experiences with your insurer? Please use the comments section to tell us all about it; your contribution may be useful to others. Thank you! We hope that the information we have provided will help you find the best auto insurance companies to work with. 

It’s Only a Joint?




When butting up the PUR adhesive, most windscreen fitters are taught to run past the starting point and overlap the joint. This technique envelops the join, and is the easiest one to program the OEM robots with. Is this the best way? Why does it matter?


Overlapped PUR Joint

This joint measured about 50mm in width, more than double the industry average. So what’s the issue? It’s a joint, and other than the somewhat abstract appearance, it looks like it ‘did the job’, right? Here’s what it looked like on the other side after cutting through it with a sharp blade:



As you can see on the left hand side, there was very little adhesion; about 4mm in fact. The shiny bit to the right of the image is cured PUR which was not making any contact with anything. If it’s not making contact, it’s useless; superfluous. A waste of product material, and potentially a catalyst for a defect in the windscreen, or glass performance.





Paint it Black



A question often asked amongst motoring enthusiasts is, “I’m having my windscreen replaced today. Is there anything to look out for?” Generally, the advice will be pretty good, and mostly based on experience. However some responses are the work of fiction; a fallacy; an internet fable, see it here.

“Before the fitter puts the new windscreen in, make sure he paints over the scratches with that black primer!”

Porsche 991 Windscreen Removal

Paintwork scratched by windscreen fitter.

This statement highlights an important issue, and just how easily vital information can be grossly misinterpreted and misrepresented. Three of the most used aftermarket polyurethane bonding systems used in the automotive glass replacement ( “AGR” ) industry in the UK are Betaseal (Dow Automotive) Dinitrol and Sika. All three are also used by vehicle manufacturers on the assembly lines all over the world. From their respective websites:

Dinitrol 530.

“Black, solvent based physical and chemical drying primer designed to prepare the cleaned automotive glasses and the flange for direct glazing. DINITROL 530 promotes the adhesion of the polyurethane sealer to the substrates, but also prevents the degradation of the polyurethane due to Ultra Violet radiation.”

Betaseal 43532

“BETASEAL 43532 primer is recommended for use as an adhesion promoter between BETASEAL™ urethane adhesives and automotive paint coatings”

Sika 206 G+P

“Sika® Primer-206 G+P is used to give improved adhesion in adhesive bonding applications on sub-strates such as glass, ceramic-coated glass and painted surfaces. Sika® Primer-206 G+P can also be used on other substrates such as plastics and some metals.”

The product descriptions are condensed, and a fuller technical data sheet furnishes us with all the finer details, but notwithstanding, the single paragraphs – at a glance – tell you what you need to know. The common denominator in all three: black primer is an adhesion promoter. Applying it provides a suitable substrate to bond to. There is no mention of it being suitable for coating bare, or bared,  metal. The emphasis of its use – by its users – is largely misplaced, and anyone using black primer – adhesion promoter – to paint over scratches is missing the point: avoid scratching the paintwork to begin with. The long term damage can be very expensive and often does not manifest itself until the car has moved on to a new owner.

BMW E46 M3 Windscreen

BMW E46 M3 Windscreen Removed

None of us are exempt from making an innocent mistake, but when we do, we learn from it; we gain knowledge. Experience is knowing all the pitfalls of your trade and more importantly, how to avoid them. We don’t paint the mistakes black with primer. We consciously avoid making those blunders in the first place. The prevention is a critical part of eliminating the risk of corrosion. Like in the image of the BMW E46 M3 above, sometimes there is no excuse to scratch the pinchweld on removing the windscreen and there is no justification whatsoever for the pinchweld to be bared of its paint when cutting back the old Polyurethane ( “PUR” ). Steve Allard of Western Windscreens in Launceston shows us just how futile covering a scratch with black primer really is. The car: a Mercedes-Benz SLK had come into his workshop for a new windscreen. It should have been a routine replacement, but the job turned into much more when he found some scratches which had been hidden with something that was not designed to protect bare metal from oxidising.

Merc Windscreen

Picture courtesy of Western Winsdcreens in Launceston.

Nobody in their right mind could claim the car is a rot box as the metal around the scratch has not rusted, therefore negating the claim or suggestion. The black primer is clearly not sufficient, and does not inhibit the corrosion of the metal beneath the paint.

Merc Windshield

Image courtesy of Steve Allard, Western Windscreens, Cornwall

Black primer is not for painting scratches. Its use is for preparing a freshly painted surface to promote better adhesion; it is used to provide a better a substrate to bond to; it is not designed to be used as a rust inhibitor, or to ‘fill in’ scratched paintwork. Even accident, or crash repair centres can be guilty of thinking that the windscreen fitter’s black primer is some magical cure, and an excuse for the painter not to put in the effort:
Windscreen Fail

Unsuitable for bonding

A Porsche 996 (pictured above) had a new roof skin replaced prior to the windscreen being removed after it cracked on a track day. Cutting back the PUR revealed some pretty alarming evidence of what was supposed to be a repair by a Porsche ‘approved’ bodyshop. There was evidence of black primer under the PUR but it had not adhered to the metal at all, and just lifted off the pinchweld like the floating thin layer of brittle black primer that it was. There was no chemical bond between to the two materials.

Those who are engaging in such practices will not be around to witness the damage in time to come. The car may even have since exchanged hands, and thus voided any warranty however subjective it may appear to be in the circumstances. The perpetrators of such careless and shoddy workmanship cannot be held culpable for the consequential loss which will invariably have been caused by their negligence, and this is as much of a crime as the act itself.

Removing a windscreen, and cutting back the adhesive that held it in is easier today than it has ever been. There are a variety of removal apparatus and cutting implements readily available whilst finely honed techniques remain the most important tool of the fitter’s repertoire. Yet there are so many who neglect to use them or are ignorant to the fact. In some ways, the windscreen fitter skills and mindset has perpetuated its own paradox. Added to this is an incessant need for speed; there appears to be so much emphasis on cheaper, easier and quicker ways to get the job done. Not many have the time nor the inclination to do a good job, or take pride in their work.

Windscreen Replacement

Appropriate and correct treatment of bare metal

It is inevitable that at some point, you are going to bare some metal as you cut back old PUR. It might be a raised spot-weld, or it might be a slip with your chisel. Within reason, and after careful assessment, you may be justified in ‘dotting’ a small mark in the bondline with primer, but if you want to be thorough, and offer a guarantee which is as robust as the work you’re aiming to complete, or is in line with the car manufacturer’s warranty, you have to spend a little bit more time than just dabbing on something which is not fit for purpose. A little more application – literally – is in order.
Windscreen Replacement

Treating bared metal with a chemically bonding agent



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Porsche 911 Windscreen: The 996

Headlights that looked like they were shaped from fried eggs, characterless exhaust notes and with an extremely soft suspension the Porsche 996 became known as the unloved series.

Porsche wrote in their 996 brochure, “Over the years we have broken with many conventions, but never with our principles. Therefore the new 911 is a direct result of more than 30 years of evolution..”  It was indeed larger, more comfortable, faster and quieter; signature 911 characteristics – developed and presented by Ferdinand Alexander Porsche – had been modified significantly, but some changes just didn’t sit right with fans of the marque. Despite this displeasure, figures made it the best-selling model in the car’s history marking the biggest turning point in the evolution of the 911.

The successor to the 993 did however inherit one common complaint in its genes. And as one frustrated owner once described,

“I have a really bad creaking noise coming from the dash board or lower front windscreen area on my 996 C4S. It sounds terrible!”

The 996 windscreen has, like its predecessor’s, been the subject of just as much fiction.

By design, the 993 and 996 windscreens are very similar. They both use a two-part trim: a frame or retainer (which fits around the glass edge) and a ‘covering frame’ which locks into it. The notable difference is twofold:

  1. The 996 trim frame is a shaped, one piece retainer which fits along two (left and right) sides and the top of the windscreen, also described as a ‘goalposts’ shape, whereas the 993 trim frame extends all around and encapsulates the entire windscreen perimeter. The second part of the ‘outer’ trim for both fits into both frames in the same way, similar to a tongue and groove joint.
  2.  During manufacture, the 993 windscreen has its trim frame enveloped under a bead of polyurethane. The 996’s trim retainer is a separate part and is fitted by hand, by the glass installer.

Both windscreens are directly glazed, i.e., they’re bonded (with an automotive grade polyurethane) to the car’s chassis. The similarities being so close suggest the cause of the creaking must therefore be the same. Well, the simple answer is yes, but in keeping with the theme thus far, it is, in different ways. The common denominator [in replaced windscreens] is usually installer error. With original, factory fitted windscreens it’s usually the aging – or degradation – of composite materials. Allowing for rare exceptions, the most common cause for any kind of creaking is movement. Two solid surfaces moving against each other will generate friction – a vibration – and voila!

At this point is also important to note that as much as there is a realistic possibility that plastics (and composite rubber materials) will be adversely affected by age and or exposure to extreme temperatures (or erratic temperature changes) there is not much evidence to support claims of product (or bond) failure. Polyurethane adhesives do not fail. People using them do. Most of the alleged ‘product failures’ are usually attributed to one, or a combination of the following:

  • inadequate surface preparation;
  • preparation in adverse or unsuitable weather conditions;
  • poor application of bonding materials;
  • contamination, or the presence of contaminants;
  • use of conflicting products thereby affecting the curing mechanism of the adhesive.

With the blame firmly pointing at the installer (also known as technician, engineer or fitter in different circles) the emphasis is placed very much on the process rather than the products. If the windscreen is set too high, as well as partially obscuring the VIN in the bottom right corner the trim frame will rub against the aperture and therefore generate a creaking or squeaking noise cue: the Infamous Helicopter Tape Myth. It’s great for protecting paintwork against scratches, and it will provide unparalleled abrasion and erosion resistance. How it made its way into 993 and 996 windscreen essentials remains a mystery. It does perversely, get a little bit of credit: it can be used as an insulating material against an audible vibration. Conversely, if a windscreen is fitted correctly so that no two surfaces are making contact with each other, the need to provide sound insulation is dispelled, while also using full fledge rigs for insulation purposes. Furthermore Helicopter or Teflon tape often introduces its own problems.

996 Windscreen2

996 Windscreen with infamous tape

Just like a lacquer or paint edge will peel, tape will also lift. It’s only a matter of time. Once it does, it can act as a dam trapping water and dirt behind it. I have removed and refitted countless creaking 993 and 996 windscreens, many of which had the ‘snake oil’ tape applied. Some of them did a thorough job of etching into the paint surface; others were just there doing nothing, looking like – and about as useful as – shedded snake skin.

Teflon tape windscreen

Shedded snake skin

In some cases, the paint had been scored (presumably where the tape had been trimmed with the blade of a scalpel). In terms of providing insulation against a creaking windscreen, tape works only when the windscreen has been fitted incorrectly. In fact, for what it achieves, you might as well wear ear defenders when you drive the car. The root cause of the creaking will still be there; the tape merely disguises it.

Trim Frame loose

Just add Neoprene chord

Another common issue comes when the trim frame (or trim retainer) separates from the glass. It’s something that will go unnoticed until you reach speeds in excess of 60mph and begin to hear what at first sounds like the noise a playing card would make against the spokes of a bicycle wheel (something all boys growing up in the seventies and eighties will identify with). Anyone hitting higher speeds (on a motorway or track for example) will hear what sounds like a radio controlled helicopter is hovering above the windscreen. A quick fix for this problem is to stuff a line (or two) of Neoprene chord; an ‘authentic’ Porsche part. Inserting the chord will simply keep the trim frame wedged against the glass edge. Paradoxically, in doing so, it simply treats the symptoms and is a long way from treating the cause. Ultimately, a new trim frame is required and this can only be fitted with the windscreen removed from the car.

996 windscreen

Adhesive on windscreen

Like the 993, the 996 windscreen leaves the manufacturer with a line of cured polyurethane applied to the glass. This is a true representation of the pattern required to install the windscreen correctly. It also acts as a buffer to aid setting of the windscreen to achieve the final and requisite position. Deviating from this mapped guide will affect the marriage of (cured and fresh) PUR, and can lead to creaking, wind noise or water ingress issues. The alignment needs to be true, and millimeter perfect. Get it wrong and there’s no recovering from it; you can’t backfill it, or make do. It will simply need to be taken back to the start and done again, correctly.

windscreen wind noise

Cause of wind noise

Check the trim around your 996; is it the correct type? If the windscreen has been replaced the installer may have used a one piece trim for fiscal reasons or in an act of complete incompetence. How can you tell? Simple: measure it. You may not even need to  as some of the trims I’ve seen used have included one for a Ford Transit which measures about 22mm in overall profile width, compared to the 15mm correct OE Porsche (assembled). In some cases, a wider trim (up to 27mm) is utilised to hide sins such as scratches, scuffs (inflicted during the removal process) paint defects, or even to conceal the presence of Helicopter Tape.

In summary, it’s not a difficult windscreen to fit. Conversely it is its simplicity which can lead to some very annoying – and often expensive – problems. Understanding the subject matter is key to achieving the best possible results. Using the same mindset as you would on an average windscreen in a fast-fit environment simply will not do. And whilst the adages and definitions of experience remain true, it’s more about attitude and application. The simple answer to why a 996 windscreen creaks could be construed as vague: it hasn’t been fitted correctly. Investigating the root cause still may not reveal a definitive diagnosis however, recognising one of the symptoms illustrated here will steer you towards the solution.

Do you have an issue with your 996 windscreen? Get in touch, especially if it is suffering from one of the issues highlighted in this post.

The Securiflex Windscreen


Porsche Securiflex Windscreen #930 #964

Porsche Securiflex Windscreen #930 #964

Found on some Porsche 930 and 964 models as standard, is what was offered as a ‘safer’ windscreen.
The Securiflex Windscreen was presented as an improved windscreen with a thin, plastic inner laminate attached to the inside surface of a laminated glass. Its purpose was to minimise the risk of lacerations caused in a impact scenario (to a passenger) during a collision. The plastic provides an additional protective coating to the inside of the sandwich construction and thus covers the sharp edges of the broken glass,  reducing the chances of cut and splinter injuries. Its effectiveness was evaluated by comparing its performance with that of a standard windscreen in simulated barrier crashes at speeds of up to 40mph (approx 65 km/h).

The Amazing, Vanishing Windscreen Chip?

Take a look at this chip:


Before repair

There’s a slight reflection in the mirror, so for avoidance of doubt, the damage is to the left of the mirror. This image was taken before any attempt was made to repair the damage.

Here is the after:


After repair

Here’s the twist: no windscreen repair resin was used. Not a drop. There is no camera trickery here either, and the image has not been edited in any way. Also, the damage was not touched in any way; no tools were used whatsoever. The process, from ‘before’ to ‘after’ took about 20 seconds.


Please note: the car was not handed back to the owner at this stage.


Please use the Comments box, or click the ‘like’ button, and all will be revealed soon.


Problems with a Porsche 993 Windscreen



The Porsche 911 993 windscreen is one of the most uncomplicated and straight forward windscreens to fit, yet they can give you many problems if not done correctly.


The Problems


It’s fairly common knowledge that the two most prolific issues which arise from the windscreen, or windscreen area of the car, are corrosion of the aperture (or pinchweld) and a very irritating vibration – or creaking – noise. Conceding that the former could well be attributed to a design flaw, both problems are usually traceable to human negligence, especially if the car has had its windscreen replaced. To identify and illustrate what these problems are, and just how bad they can get, I have chosen this 1995 car on the basis of its age, condition and comprehensive service history.


The Car


This 993 is extremely ‘clean’ and looks to be a fantastic depreciation-proof investment.  A C4 coupe 6 speed manual, she’s flawlessly finished in a Polar Silver metallic paint with an unmarked – and as new – gray interior; hard backed leather sports seats to boot. The car has been well maintained and between just three former keepers every mile, every turned nut and bolt, has been meticulously accounted for. The current owner wanted to address two annoying problems which first began to surface a few months after he’d bought the car: corrosion (on the scuttle below the windscreen) and, “it sounds like the pitter patter of rain” he said.

NB: I have covered the VIN in order to concentrate on the subject, and not on the car or its identity.


The Evidence


Like with any windscreen replacement, most car owners will see the finished product; in most cases, they start with a damaged window and when the work’s done, they’re presented with shiny new screen. If there are any issues in the finish, sometimes they’re immediately obvious but some problems will not manifest themselves until later. One of the most annoying scenarios is finding such a problem as the new owner of the car. The story with this car started with such a sketch.


Porsche 911 993 Windscreen

Porsche 911 993 Windscreen


To be fair to the current owner, it’s an easy detail to overlook when looking over an otherwise fantastically maintained – and presented – car. “It was only until after I got it home and wondered if it should be like that,” he said “I decided not to query it as I was so pleased with the car”. Some six months into his ownership, his ear ‘tuned in’ to the infamous creaking noise and like many other Porsche owners, he put it down to a dry bush or guessed that it might be a tightness in the dashboard somewhere. The car subsequently ended up with a Porsche independent who immediately spotted the gap in the damming rubber, which prompted him to look for other telltale signs. On closer inspection, there was no doubting the windscreen had been replaced. Underneath the outer trim, or ‘sealing frame’ was not a pretty sight.


Poorly fitted Porsche windscreen

creaking windscreen


Please also note that there may have been approximately a year (or more) between spotting these issues and having them corrected; the bubbling paint was not as bad when first noticed.

My remit was to remove the windscreen so that the bodyshop guys can tackle the corrosion. The following pictures tell their own story.


Porsche 911 993 Windscreen Problem

Chassis view window painted over!

Creaking windscreen

Rust underneath poorly applied adhesive











The windscreen was removed – intact – and whilst it was difficult to ascertain if had been fitted from new (or removed and refitted) there was no mistaking the attempts to cover up a multitude of mistakes.


Windscreen woes

Chassis view window cover-up

Creaking windscreen

Excessive corrosion to pinchweld










The Work

Leaving the bodyshop guys to deal with the corrosion (which pointed towards some over zealous use of a knife by a previous installer) the windscreen needed some extensive correcting of its own before it would be ready for refitting. My suspicion is that for whatever reason, the windscreen had already been removed and refitted. This may have been in a bodyshop (for paint.corrosion correction) or possibly even to rectify a replacement problem such as creaking, leaking or wind noise.


The Clean Up


Windscreen Clean Up


Windscreen Cleaned











There was a lot of making good to be done and found hidden beneath the mess was one of the reasons why these windscreens creak: silicon contamination. In order to obtain a more flush-fitting finish, the 993 front screen comes, from the manufacturer, ‘pre-encapsulated’ within the trim frame (like the one on the heated rear window, this is not available as a separate part). The plastic-coated frame is slotted onto the glass and provides a groove for the outer (rubber) trim to lock into. With the trim frame around the perimeter, a bead of Polyurethane adhesive (PUR) is applied over the line where the trim frame meets the glass. The idea is to bond these two parts together and in doing so, provide a raised profile to which fresh PUR is applied when fitting the windscreen to the car. A mistake many make is to cut into this pre-applied PUR. In this case, there was little left of the factory-applied PUR; the silk-printed ceramic frit had been obliterated with black adhesion promoter and the trim frame was loose. Given how contaminated the substrate was, the best policy was to cut right back to the ceramic coating; much of what was left of the existing PUR simply peeled off.


Creaking Windscreen

Not good enough


The next steps were crucial. Nobody likes doing preparation work; it’s boring, it takes time and you cannot see an immediate result.  However, the importance of prepping the substrate sufficiently couldn’t be more important in this case. This screen was riddled with silicon and had to be removed before we did anything else.


Porsche Windscreen

Removing contaminant

Creaking Porsche Windscreen

Clean as a whistle










With the contact surface neutralised, work began on getting the trim frame back on and bonded under fresh adhsive. There are a couple of points which I am purposely omitting at this stage under the banner of trade secrets but mainly because this is a very involved remove and refit of a 993 screen and that those particular details would probably not apply to the fitting of a new screen.


Creaking Windscreen

Trim Frame fitted and fresh PUR adhesive applied


With the fresh PUR applied, the windscreen is left in a cool, dry room to allow the adhesive to cure through to its core (brand, temperature and humidity dependent, this could take up to 84 hours). For your information, I use a Sika AGR OEM Approved PUR adhesive system. Once the PUR has cured, some trimming may be required to allow the screen to sit at the required height.


The Repainted Car

From the moment the fresh paint has been baked, the car must be allowed to cool down for 24 hours after it is removed from the oven. This is part of the paint curing process. Sika recommends a bonding process specifically for freshly painted cars and this process is followed according to their guidelines.


Creaking Windscreen Cure

Fresh Paint

993 Windscreen

Adhesion promoter applied










With the inner damming rubber in place, there are some minor adjustments to be made before the windscreen can be bonded back into place. These tweaks are made from ‘dry’ fitting the screen and ascertaining the where correct position is in relation to where – and how – the screen will sit on freshly applied PUR. Some final preparation touches are made before setting the screen into position. And she’s in:


Creaking Windscreen

View from inside – antenna no longer visible.


The final step is to make sure this problem doesn’t creep back in years to come.

And Finally


Some shots of the finished job.


Porsche 911 Windscreen993 Windscreen

Windscreen Porsche

993 C4S Windscreen Remove and Refit: Done.

I invite, and welcome your comments.





Contaminated Windscreens: the Missing Link


With each windscreen replacement, a key component of the vehicle’s structural system is put into place. The crucial part of this assembly is the bond between two contact surfaces: the glass and the car (specifically the aperture, or pinchweld). This critical area can develop air and water leaks, and at worst, can compromise the overall safety of the occupants (in the event of a collision or rollover scenario) if contaminants are not removed as part of the preparation process.

Preparing bonded windscreens used to be a bit of a grey area.

Most modern car windscreens have a black band, or ceramic ‘frit’ around the perimeter of the glass. This essentially provides a suitable surface for the Polyurethane (PUR) to adhere to, as well as acting as UV block which, can break down the bond.  When preparing for installation, the glass must be decontaminated to rid this substrate of any substances which may have been introduced during handling, such as grease, oily fingerprints and other substances. The performance of the adhesive can be adversely affected if the glass – and aperture – is not prepared correctly by following the adhesive manufacturer’s process instructions.

New products are now readily available after the recent discovery of one particular – invisible – substance which is deposited on the glass during manufacture. Silicone residue interferes with the adhesive bonding and following extensive research, has now been identified as a cause for bond failure. Previously, some windscreens would reveal areas of wax-like deposits which installers would try and scrub away with an abrasive cloth. But back then, nobody really knew what that substance was, and most installers would take a leap of faith relying on the adhesive manufacturer’s bonding ‘kit’ to do the trick.  Research has proven that standard glass cleaner, or abrasive cloths will not remove silicone contamination.

Today, leading PUR manufacturers recommend that all windscreens are decontaminated with an appropriate agent and neutralised of silicone interference. Whilst some windscreens, especially OEM branded versions, show little or no signs of decontamination, the wisest approach is to go through the removal process as a matter of course.

But there still are grey areas.

Presently there is no official word on whether or not OEM windscreens are decontaminated before being fitted to cars during assembly. But there is evidence to suggest that these ‘genuine’ screens go through a different manufacturing process to their aftermarket counterparts. One of these differences may well be a ‘washing’ process so that glass units arriving at car assembly lines are ready, and fit for purpose. This – if true – would make sense evidently in the interests of a time-saving exercise for car manufacturers to benefit from. One thing however is very clear: most windscreens will show some degree of contamination.

Detecting silicone deposits on glass is very simple: if the glass surface (two-three inch wide area around the edge  of the glass) appears to repel (the adhesive manufacturer’s) glass cleaner, the glass is contaminated.

But what if the glass manufacturers have pre-applied material to that area?

Pre-applied primer on windscreen

Pre-applied primer on windscreen









Windscreens, such as for the Porsche 996 and Golf Mark 4 are produced with a pre-applied bead of PUR. Are these screens decontaminated before this ‘pre-encapsulating’ process? How about other screens, where a primer line is applied to the frit? Many windscreens will also have extruded trims, or mouldings bonded to the glass during manufacture. Installers are taking the same leap of faith when they are applying bonding material to glaze these units directly to the vehicle and are reluctantly relying on someone else’s work for the integrity of that bond. It’s an almost impossible task to remove cured primer and PUR. This Fiat Bravo screen is produced with a formed PUR buffer at the top and bottom of the screen. This is bonded to the glass sandwiching a coating of black adhesion promoter, or primer, between it and the glass surface. A test concluded  that the sides of the windscreen revealed heavy deposits of silicone which, makes a strong claim that this windscreen was not decontaminated before these additional items were introduced.

This windscreen is contaminated

Contaminated Fiat Bravo Windscreen

PUR adhesive manufacturers and windscreen installers have identified a problem and this partnership has brought about a better awareness in how to achieve the best results for correctly bonded – and safe – windscreens. But the industry needs better communication from glass manufacturers. Glass production is a huge global concern with thousands of units being manufactured every day; there are windscreen plants all over the world and UK suppliers are busy doing what they know best; windscreen replacement companies are striving to do the best they can by investing in training and using the best available products. Technological advancement in PUR formulation has given us the best adhesive systems the trade has ever seen, and with glass being the chief character in this plot, the industry deserves better communication from the glass manufacturers.

Windscreen Manufacturers – What do they Really Mean?


“We fit OEM standard glass” is a statement trotted out by many windscreen replacement companies, and unless you are fulfilling your offer by fitting genuine, car manufacturer-branded or OEM branded glass, you’re well, misleading us all. The end users will think they’re getting manufacturer authentic, genuine parts but they’re not, and most will be unaware of the difference. Windscreens and other vehicle glass which are not OEM branded are often described as ‘OEM equivalent’. Another confusing statement.

This confusion can be traced back to the manufacturers.

But first and foremost, a distinction must be made between OEM branded windscreens and (glass) and (glass) manufacturer-branded aftermarket, or what some people may refer to as ‘copy’ glass. There are some automotive glass manufacturers who produce ‘genuine’ glass which is fitted to cars during assembly as well as supplied to their OEM (or, main dealer) parts networks; some manufacturers cater for the aftermarket glass replacement (AGR) market and some will supply both industry sectors. Some of these brands are better known than others, but how can you tell the difference? For example, Guardian Llodio Uno S.L manufacture glass for some Audi models and the glass will display the Audi ‘four rings’ logo above their own. Guardian Llodio Uno S.L also produce a ‘non branded’ glass which does not feature the Audi logo. A question often asked is, is it the same glass with one obvious difference in detail? Many installers will tell you it’s the same glass off the same production line. There also some windscreens (and vehicle body glass) which fall into both categories. Pilkington produces windscreens for SEAT cars; the Ibiza model for example, will clearly feature the ‘SEAT’ logo. A windscreen via an authorised SEAT dealer parts seller will also feature the same logo however, the same glass from an aftermarket supplier will have the SEAT logo removed (usually by laser) and overlaid with a black Pilkington logo:

Seat OEM Windscreen by Pilkington

Seat OEM Windscreen by Pilkington

Pilkington Windscreen for Seat

Pilkington Windscreen for Seat










Again, no definitive answer why this is. It could well be required due to restrictions imposed by commercially complicated bureaucracy. But Pilkington’s Executive Director Pat Zito ‘certifies’ their products by stating:

“Pilkington manufacturing processes and products meet the highest quality standards set by the world’s leading vehicle manufacturers. All Pilkington glass products supplied are always certified ORIGINAL EQUIPMENT PARTS and ORIGINAL SPARE PARTS”

Aftermarket (AGR) glass versus Genuine (OEM). Same, or different?

“Antonio Girbrau Ortega, Superior Ind Engineer and Quality Manager of Guardian Llodio Uno S. L.


That all replacement glazing produced by Guardian Llodio Uno S. L.., identified with the Guardian logo, are manufactured according to the same specifications and standards as the Original Equipment used for vehicles. It means that the replacement glazing has the same quality as the Original Equipment parts.

Besides, the Company is in the possession of the following Quality System Standards:

ISO 9001 : 2.000

Automotive Standard QS-9000

Automotive Standard VDA 6.1″

At face value, it all seems fairly straight forward, and glancing at the Quality Manager’s statement appears to confirm that there is no “quality” difference between an OEM Guardian glass and a non-branded equivalent.

Andrea Vietti Ramus – Quality Manager ARG Europe for Asahi Glass Company (AGC) and Spintex glass – has an interestingly different choice of key words:

“This is to confirm that all products made by Splintex for the ARG market respond to OEM main technical and aesthetic characteristics.
Furthermore, all Splintex products are homologated according to:

European R43 regulation, revision 1 – add. 42 (March 1987) of UN and European Directive 92/22 (1992)
American Standard ANSI Z.26.1.

Finally, please note that Splintex products specifically for the ARG market do not bear the car manufacturer logo”

What exactly does ‘respond to’ mean? There is a criteria set out and our products respond to it? It would be reassuring to the end user if products surpassed those prerequisites, surely? But if their non OEM glass “responds” merely to “main technical and aesthetic characteristics” could mean that the glass looks the same (aesthetically) and is the same size (technically). This statement could, technically speaking, apply to mock designer handbags or faked expensive watches, “this watch responds to Breitling’s  design criteria”.

Taken from their website, Polish manufacturers Nordglass state:

“NordGlass company produces high-class windscreens for over 650 popular car models sold in Europe. Our company also deals with the distribution and selling of side and rear windows as well as accessories necessary for the assembly of car windscreens.

We offer our Customers a product that is compliant with the strictest requirements of the industry, for original parts as well, with all necessary legal requirements. Our products meet OEM standards both in terms of materials used and technological process parameters, therefore obtaining the assumed technical specification of this product line.”

The glass manufacturing business is now busier and more competitive that it has ever been. There are Chinese brands, Polish, South African and Turkish manufacturers all pitching to produce more and more glass for the AGR and, or OEM markets. It’s even evident on new cars; the front windscreen, the door glasses and the heated rear window might all bear the same car manufacturer logo, but the glass itself might be from three different manufacturers.

One thing we can be sure of is if your glass comes via an OEM source and is branded with the vehicle manufacturer logo, it’s about as genuine as you can get. But with the others, take your chances. It looks the same, it might measure the same; the product ‘responds’ the same, but nobody can tell us if it really is the same.






Textbook Bullseye

First, the impact mark/point is tidied. The break is then dried to remove any moisture present.

Stonechip Repair Windscreen

Windscreen Chip Repair BMW X5

Once the optimum working temperature is achieved, most of the air is removed from behind the impact:

Windscreen Chip Repair

Vacuum stage

The resin injector is positioned over the break for the next step:

Windscreen repair equipment

Glass Doctors bridge with Novus injector

A pressure (and if needed, vacuum) cycle is applied to remove any remaining air and the resin is cured under Ultra Violet light. The final stage is to fill the impact crater with a finishing resin which is also cured under a UV lamp.

Chipped Windscreen Repair

Job done

A textbook bullseye and one of the easiest to repair.