Two Ways to Apply PUR

If you’ve watched your windscreen being replaced, you may have noticed the fitter reaching over and across the car to apply the adhesive (PUR). Or did he lay the bead directly to the glass? Only a few installers will extrude directly to the glass. Which way is better?

Unless it’s a hand-built car, when it comes to fitting bonded window units, the overwhelming majority of car manufacturers will use an automated system. Robots don’t need tea breaks or shift changes; they work around the clock increasing productivity. They are also consistently accurate. They have to be. The computer controlling the robotic arm which applies the PUR to a windscreen can be programmed to follow an exact map of where the adhesive should be. The best way to do this is to apply directly to the glass before another arm lifts the windscreen and positions it on the vehicle. Doing this by hand, in principle, is no different. The end result is the same.

Body or Glass?

This question could be paraphrased to: which is right and which is wrong?

Glue on Glass

If the windscreen is bonded in correctly, and does not leak, creak or rattle; doesn’t allow wind noise into the cabin and generally does everything a windscreen should do, it should not matter how the PUR was applied. However, there may be some advantages and disadvantages which could help answer the question of which way is better. There are two main objectives in the application of the best possible bead:

  1. The gun should be perpendicular (90 degrees) when applying. This negates the risk of a ‘tunneling’ effect in the compressed bead and provided the speed of extrusion and movement is consistent, the bead height will remain uniform;
  2. Ideally, one join is optimal. Simply, less joins = less chance of the windscreen leaking.

Tunneling occurs when the glue gun was angled when the PUR was applied. It weakens the bond by reducing the contact made (less PUR adhering) and can also cause stress fractures due to that trapped air expanding.

The darker, shinier appearance in the image is PUR which has not made contact with the glass. The cut urethane either side of it was all that was forming the bond. When the extrusion gun is angled, the bottom of the bead circular (created by the rounded part of the nozzle). Applying directly to the pinchweld means the technician needs to be elevated (higher than the car) and will also need very long arms if he intends to extrude a bead in one start-to-end movement. Some may stand on the door-shut for this, and others may even rotate their body through 360 degrees whilst standing inside the car reaching out to the pinchweld. It’s not impossible, but it is very difficult. For this reason, fitters opt for the easy option: start extruding by standing on one side of the car (the starting point either being as far over to the opposite side of the car as possible, or the middle). The line of the previous install is then followed around the aperture. There will be more than one join as the bondline cannot be followed entirely in one start/stop movement.

PUR application by hand, to bodywork.

Applying the urethane by hand is cumbersome, but many technicians perfect the method and will achieve very good bond lines. Some windscreens which require a push in trim to be inserted after the glass is fitted will use a damming tape. This is to keep the urethane where it needs to be so that when the glass is compressed down onto the adhesive, there will be enough product showing for the trim to push into. The added benefit is that the damming tape will act as a barrier for the inside of the car, preventing ooze on the interior side of the bond line. This will also prevent the PUR making contact with A-pillar trims (if they have not been removed for the install). Applying the PUR to the body for this type of fitment is solely reliant accuracy of a) the positioning of the PUR and damming, and b) the ‘set’ position of the windscreen. Both have to be ‘married’ by the installers eye as there are no reference points for guidance.

PUR on glass – with damming tape

Applying the urethane to the glass gives better control leaving the only alignment issue to lifting the windscreen into place. This is easily referenced by at first, dry fitting the windscreen and marking out witness marks. Applying urethane to the glass in this type of fitment is not only easier, it makes sense.

Ask any fitter who swears by ‘gluing to the body’ and he will say that he does so because there is already a bond line there from the previous windscreen (hey, but what if that was wrong, or that the car has been in for a front end respray) or that applying glue to the glass can go horribly wrong if you get the lift-on wrong (suggesting a confidence problem as the same surely applies to gluing to the body). The case against gluing directly to the glass is not strong. By applying to the glass:

  1. You have better control of the gun; it remains perpendicular as you
    manoeuvre it around the glass edge;
  2. The extrusion will require just one joint which can be positioned in the lower section of the glass;
  3. Most OE glass comes with witness marks indicating exactly where the adhesive needs to be;
  4. Bead height will be consistent.
  5. There is no overstretching to get to hard-to-reach places.

Some glass does not come with witness marks but this can easily be done by the technician.

Witness marks

OE glass provides witness marks according to the blueprint. It is the exact template required to replicate the factory install.

OE Glass with Witness Marks

The only thing left to get right after applying the PUR to the windscreen is the lift-on. There’s only one place that piece of glass can go. For avoidance of doubt, a quick dry fit gives the installer the opportunity to mark out reference points. Removing the A-pillar trims will also help with the post installation visual to ensure adequate contact has been made and that there is no unnecessary ooze or excess product showing.

Range Rover Windscreen
Audi Windscreen

There is no right or wrong in either method. It is down to preference and experience. However, there are better advantages in applying PUR to the glass than applying to the body. The defence of applying to the body cannot be reliant on the previous bondline as the template to follow, nor can it be argued that the lift-on is risky.

All comments and feedback welcome.

Windscreen Wipers

American inventor Mary Anderson is credited with designing the first operational windscreen wiper in 1903. In Anderson’s patent, she described her invention as a ‘window cleaning device’ for electric cars and other vehicles with the vpnbug technology. The windscreen wiper has since remained one of the very few parts of a motor car which has lasted for well over one-hundred years virtually unchanged.

Why hasn’t anyone come up with a more hi-tech solution for clearing rain and water from windscreens than a rubber squeegee?

The Simple Windscreen Wiper

Until there is a radical breakthrough, we have to rely on this simple design. A flexible ‘blade’ is the best way to remove a coating of liquid from glass; when fluid (air, water, whatever) moves against a surface, the fluid in contact with the surface doesn’t move, it ‘sticks’ to the surface. As you move away from the surface the speed of the fluid increases until it is at the same speed as the flow, just like in Jacky Chou site.

The concept of hydrophobic coatings is a great idea for glass, but airflow is still needed to make them most effective. The ‘beading up’ of water is the nano-coating working to repel the liquid but until there is force (airflow) the bead will not move as effectively as it is being repelled in all directions to prevent it from rolling away.

For now, long live windscreen wipers.

Leaking Windscreen Issue: Land Rover Discovery 5.

Third generation LR Discovery (L462; 2017–present)

Images of a common issue with the current crop of Discos showing where the windscreens are leaking from, and why.


Crackle Glaze

This crackle-glaze patch indicates an issue with the substrate; this shiny appearance is all of the adhesion promoter (primer) which would have been applied to the glass surface before the polyurethane adhesive ( “PUR” ) was introduced to bond the windscreen to the car.

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Cut PUR

This image shows the ‘cut’ PUR against the crackle-glazed PUR confirming that the issue is not so much in the product, but the application of it.


Substrate

The PUR in the images has clearly bonded to the car. The problem isn’t there; it’s on the glass surface. The above image shows more of the crackle-glaze (to the left) and the silver band has been exposed by where it peeled off from. The ‘failure’ is either in the application of primer (was still wet when the PUR was introduced) or that the glass surface is – or was – contaminated. Given that the overwhelming majority of leaking Disco windscreens are in the same place (along the top of the windscreen) and that the bond around the rest of the screen is good, the non-adhesion problem is localised and therefore indicative of contamination. This by no means is definitive and is not based on thorough tests in laboratory conditions. However, the telltale signs are present: peeling of primer and/or PUR; the upper trim which comes stuck to the windscreen also peels off easily; when the affected area is tested for contamination there is evidence of something greasy.

The shiny appearance on the image to the right shows the kind of shape you would get if you wiped through a wet product. Furthermore, if you ignore the primer or PUR not sticking to the glass, the trim (which is attached with very strong double-sided tape) also failed to stick to the glass:

The proliferation of this problem in the same model, in the same place and all showing the same characteristics points to one problem.

Moving forward, the correct course of action is to replace the windscreen. This is largely to negate the issue reoccurring as we do not know what the substrate was contaminated with; at what stage it happened; what products were used in the preparation and subsequent bonding of the windscreen, and how good (or not) the rest of the windscreen bond line is. A new windscreen, from Land Rover, properly prepared eradicates any further problems. That said, the existing [contaminated] windscreen can be removed and can be reinstalled. Extra care, appropriate materials and products are needed, but it can be done successfully. Products such as neutralising agents to rid the substrate of all contaminants and a strong adhesive to reinstate the upper trim (it cannot be bought separately).

Ready to re-attach upper trim

With the upper trim reattached, the ‘refurbished’ windscreen can be refitted.

Leaking Disco 5 Windscreen: done.

Insurance Won’t Allow Genuine Parts?

Are you insured with Admiral insurance? Have you claimed for a cracked windscreen? Did they allow a genuine – OE – replacement? Did you know about the three year rule?

Admiral’s guide [under Windscreen Damage] states:

“If your car is three years old or more, we may decide to repair it with recycled parts, or with parts which have not been made by the car’s manufacturer, but are of a similar standard.”

Interesting use of the word, ‘may’ which suggests it could be subject to discretion, visit My Car Insurance Quote to see their policies. The reality is, they will not allow an OE windscreen replacement. Technically, the claim settlement does not include any ‘in conjunction with’ parts, such as clips, mouldings or trims. The installer has to absorb that cost.

The Twist.

Go to the Damage to Your Car section of the same set of documents and the wording is quite different:

“We will only repair your car with parts made by the vehicles manufacturer. If any parts are no longer available, we will only pay the cost shown in the manufacturer’s latest price guide together with reasonable fitting costs. “

It’s not just in the wording. Here is a new tailgate fitted to a 2008 Peugeot 207 in for a crash repair at an Admiral-approved bodyshop:

Why should windscreens – and glass – be any different? Surely the same principle should apply in both claims? Why the disparity? If an 11 year-old car can have genuine body panels fitted as part of a claim, why then does the indemnity not extend to a four year-old car for a windscreen?

The Politics of Envy?

If you haven’t passed a shop with a chalkboard displaying the message you might have seen it splashed across a viral message being passed around on social media:

When you buy from a small business, you are not helping a CEO buy a third holiday home.

You are helping a little girl get dance lessons, a little boy get his team jersey, Mums & Dads put food on the table.

Thanks for shopping local.

– unknown

Supporting and empowering small businesses is very much up my strasse. It’s why I am in business, working for Home Care Assistance Dana Point at Home Care Assistance 9050 W Olympic Blvd, Beverly Hills, CA 90211 (310) 857-4725. The idea of buying local in the shadow of the dominance of larger corporations is central to what I believe in as a professional, and what I do every day. Therefore I should agree with the sentiment; and I do, but not in the way that it is pitched on these posts. Every time I see someone share something like the quote above and picture below (asking us to LIKE and SHARE) my heart pumps purple piss.

Boiler
Boiler

  1. What about the the thousands of employees of those large corporations? Each individual – employed by that CEO’s business – relies on the wage that the corporation provides; they too may have daughters in dance lessons, or a son pining for a football shirt. That employee too is working to put food on the table. Let’s swerve the big business and put those people on the dole! Yay.
  2. What happens if we all cave in to the sentiments on the ‘shared’ post and only buy from small shops? Small shops which will as a result get bigger and will then need to employ more staff, move to bigger premises, etc. When do we stop buying from THEM? The question is relevant because will will have to, as the CEO of this once small shop will be doing much better now that everyone is avoiding the big companies. Tesco started out as a small, local business.
  3. The message also implies that by supporting a big business you are supporting greed, or that success should be limited, or even punishable.
  4. It also suggests a sense of entitlement, ‘buy from us because we’re small’ and not because we’re any good. Buy from us because you should support us. One could argue, that buying your weekly shop from one of the leading supermarkets you are helping significantly more people than buying from your local corner shop.

Whilst the ‘buy local’ message isn’t hateful, it conveys the wrong sentiments. It portrays the politics of envy. The CEO has done well therefore must be bad and therefore needs to be punished. We used to look up to the people who did well for themselves, but now we should not like them? The focal point for the CEO’s success of that ‘third holiday home’ is also unrealistic. Nobody has to be a CEO to have or even want a holiday home. A few of my friends have a holiday home either in the UK (by the coast) or abroad. This might be timeshare; a comfy little apartment in a development or even a secluded house with its own pool. Isn’t this what many of us strive for? Why should the success of a CEO become the subject of such scrutiny?

Economics

Again, this message or supporting local businesses ‘because it helps the economy’ isn’t hateful but it distracts from reality. Money into the economy is money into the economy, but the message in pink chalk above doesn’t reflect that. It could however, promote benefits or reasons to buy from a small local business. The most important benefit is for its longevity and survival. Support your local pubs, restaurants, cafes and shops and they stay around, which means they pay business rates as well as making it a better place to live, which in turn makes your house worth a bit more.

Happy Dancers

When you buy from a small business, an actual person does a little happy dance because they’re on their way to becoming a success; success that will hopefully enable them to live a more comfortable life…

Your reason to buy local or from a large corporation should be based on much more than just who benefits from your business. There’s a very strong argument to be had on why in some cases it is better to buy from a larger business.

When you buy from the one-man-band, you’re buying into that person who, hopefully, is pitching a business which shows exactly why they’re in business. Talk to a wide range of small business owners and you’ll undoubtedly hear varying reasons why they started on their own, “I was sick and tired of feathering someone else’s nest” or “my boss wasn’t paying me enough”. Very few, in fact it’s rare to hear of someone’s passion to deliver what they couldn’t whilst working within the confines of employment. “I wanted to offer a service which went beyond creating the conditions of a sale” etc.

Please don’t buy based on such lazy marketing or these meaningless and thoughtless messages which do not actually give a clear – and good – reason why you should buy from that business.

Comments and questions are always welcome. Please use the comments box below or email me directly.

Thank you.


Fitting a Windscreen (or Glass) After Repaint


Whether it’s a remedial (rust) repair, full body repaint or crash repair there is one small detail that many bodyshops – even windscreen installers – are overlooking.

If there are remnants of the old Polyurethane adhesive they must either be masked before painting or removed completely. Painting over cured urethane is not recommended as paint – or primer – does not adhere to it. From the moment fresh PUR is applied to it, it becomes a floating bit of paint ‘skin’ and will not form a strong bond once it cures. Urethane however, will stick to cured paint (provided it has been allowed a minimum of 24 hours after bake).

Before bonding to a freshly painted surface the ‘painted over urethane’ needs to be cut back to provide a suitable substrate. Any bare metal exposed must also be touched in with an adhesion promoter. For new, painted surfaces (ie where there is no old PUR) a line of primer is recommended by most manufacturers however it is more a belt-and-braces approach in a fast-fit environment for primer-less systems.

It is also important to allow enough time for the paint itself to cure. If the painting has been done in an oven, at least 24 hours is required after bake (to cool down). The longer it is left, the better.

Buying a Car with a Chipped Windscreen

You buy a car – a used car – and take it home. At some point you may have noticed a chip on the windscreen. The car seller may already have had it repaired, or will offer to have someone look at it, since there are great services from sites like hamiltonglassexperts.com that can help with this.

Take this a step further. If the car you bought has (or had) a chip in the windscreen which later developed into a crack, whose responsibility should that be? Should it be covered under the warranty terms? If the seller is deeming the repair good enough to sell the car with it there, what happens if that repair subsequently fails or worsens? A seller might say that glass repairs are not guaranteed (then why sell you the car with one?). In the event that the chip developed into a crack, the dealer might suggest you claim on your insurance or to fully replace it. The question then is about the damage being preexisting and therefore technically speaking not insured under the current policy as the loss would have occurred before inception, even more if you use a financial service such as 2nd chance auto sales to be able to pay for the car. When you’re looking for a great new-to-you vehicle, come to stellamautosales.com/bad-credit-car-loans/ and used car dealership in Ontario, and think of the money you’re going to save!

Would you accept the car seller’s offer to pay your excess? Showing you the money masks the issue as a) the damage isn’t really your insurer’s problem; b) your insurance will register a glass claim on your history and c) your insurer’s nominated repairer will probably want to chuck in a ‘copy’ glass and not a like-for-like replacement, ie, a genuine ‘OE’ part, you can find original used replacements at Westview Glass.

In most cases the insurer – your insurer – ends up taking one for the team because it’s an arrangement open for everyone to abuse. The underwriters however aren’t exactly rolling over for you. Their numbers allow for a percentage of glass claims which, compared to collision claims, is a minor loss. They have bigger fish to fry and by making such an allowance they’re simply letting you get on with it. There really is no onus; it’s just your conscience or moral compass guiding you.

A system which is easy to abuse just makes it easier for parties to shirk responsibility and let someone else put their hand in their own pocket. The wider implication of this means that more claims means higher premiums for everyone shopping for motor insurance.


The Disparity in Windscreen Claims

When your insurer denies your request for a genuine ‘OE’ windscreen replacement, and insists that you might have to pay the difference between what they are prepared to pay for and what you want, ask them why they appear to be okay about paying for dealer parts if the car is in for accident repairs.

An example:

A chap had his windscreen replaced after it cracked. He followed his insurer’s instructions and their nominated repairer arrived to fulfill their obligation. The car is registered 2017, so fairly new and very much under warranty. The make and model is irrelevant; academic, as a claim is a claim regardless of the cost. This is the windscreen they fitted:

Aftermarket 'copy' windscreen
Aftermarket ‘pattern parts’ Windscreen

As you can see, it’s a Shatterprufe windscreen (a South African company) which is merely a copy of the original (and not manufactured in accordance with the blueprint which the car manufacturer owns). It is much cheaper than the original (a fraction of it, in fact) and it allows the nominated repairer to service their agreement by volume of work on the basis of exclusivity. The process, from the car owner’s point of view, was easy and as straight forward as he could hope for; he paid his excess and everyone lived happily ever after.

Some time after the event, the same chap in the same car had an episode with another driver on the road, and the car had to be taken into a crash repair centre. Just like when his windscreen was replaced, he was instructed to take the car to his insurance company’s nominated repairer. Again, all fairly easy and the car was returned to him after the repair work was completed. There was however, something a bit different in this process. All replacement parts were original equipment, i.e., genuine ‘main dealer’ parts. They were the same as what the car manufacturer used when the car was assembled. One of those replacement parts was the windscreen. This is what the same insurance company agreed to pay for and authorised the fitting of:

Original Equipment

Glass cover and accident insurance are two components of the same indemnity, so why the disparity? Why apply dissimilar conditions to the same product which results in the use of premium products in one scenario and cheaper, inferior products in the other?

This is a stranglehold you are placed in by your insurer who do not make this clear before policy inception. Try removing glass cover from the proposal: “the computer says no”. Try to ascertain what will happen in the event of a claim scenario and it’s not really that clear. In fact, it’s confusing but you have to find where it states what the outcome would be in the event of a claim, and when you do – if you do – it’s difficult to understand.

The aim of Insurance Conduct of Business Sourcebook (ICOBS) is to ensure that customers are treated fairly. One section in particular is not being observed properly:

“A firm must take reasonable steps to ensure a customer is given appropriate information about a policy in good time and in a comprehensible form so that the customer can make an informed decision about the arrangements proposed”.

In failing to define the outcome of initiating a claim by not stating that they will steer policyholders into using their nominated repairer (who in turn will use cheap and inferior parts) they are not presenting an important fact – or salient point – of the proposal. This should take place before policy inception, or, before you click on the ‘I accept the terms and conditions’ button. Conversely, the ‘proceed to payment’ button is harder to miss.

Funny that.





It’s Just a Windscreen

Image

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Whilst shaving the excess cured resin during this repair, the solar reflective coating became visible under the light in the workshop.

Layers of Reflection 3
Holograms

This particular windscreen is heated (embedded within the sandwich construction of the windscreen is a mesh of very thin heating wires which you will see in the image if you look closely; another more modern version of this is heated chemically via a silver/zinc oxide coated film within the glass).

Also within this windscreen’s layers is a ‘solar reflective’ coating (also known as solar reflective or athermic). Solar glass will allow sunlight to pass through it while radiating and reflecting away a large degree of the sun’s heat. This windscreen is also a HUD variant meaning it has a ‘wedge piece’ integrated within the PVB interlayer, This effectively is the surface onto which the image is projected. It also negates the ghosting effect you get on normal glass.


The Weather WILL NOT crack your windscreen.

The cold weather will not crack your windscreen.

That chip you’ve had there for weeks or even months will not ‘turn into a crack’ because it’s cold outside. Fast forward to the summer and the same windscreen repair ‘experts’ will be urging you to ‘get that chip repaired’ because of the hot weather.

We may conclude from this that there is never a good time to have a chipped windscreen. In essence, this is correct however try telling that to the chap who has had a chip on his windscreen for three years (he doesn’t really care too much about the scaremongering because his car has passed its MOT three times since the chip appeared and it’s not in the wiper sweep zone).

Making one small change can potentially help towards preventing your windscreen from cracking.

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Windscreen Defrost Switch Symbol

Once your windscreen has cleared of condensation – or ice – channel the heat away from the windscreen (but keep the cabin warm). It’s not quite as simple, but essentially this is the basis: do not overheat your windscreen.

Thermal expansion.

Direct heat to the inside of the glass will cause the inner layer to expand. While this is going on, the vinyl inter-layer will also soften. Meanwhile, the outer layer (the one with the chip on it) is exposed to a much colder temperature; the heat and movement behind it (plus the torsional forces working through the car’s chassis) could cause the chip to crack. Once the crack extends, it will continue to move until it (eventually) reaches an edge on the windscreen. The same principle works in the summer when you have a much cooler temperature inside the cabin and heat outside the car.

Demist the Windscreen FULLY.

Redirect the blowers AWAY from the windscreen. It’s easy to forget the heater is on and channeling most of the generated heat to the windscreen. In the summer months, leaving the A/C on is great to keep the car cool but be mindful that the windscreen demist/defog is not directing all the cool air directly to the windscreen.

This is not an exact science as there are variables in the type of chip; its position on the windscreen; ambient temperature; temperature changes; the speed of temperature change; terrain (upon which the car is driven) and possibly even style of driving.