You’ve gone through the car with a fine tooth comb and it’s faultless; the HPI report comes back all tickety boo and you exchange money for the keys – and V5 – before hitting the road home. It’s your new pride and joy. But there’s something not quite right, and you won’t know just what that is until it shows up as a costly problem to fix.
Kicking a tyre won’t find a defect just as much as knocking on the windscreen reveal if it’s been replaced or not. Seeing a ‘VW’ logo merely tells you that the glass is a genuine part; it doesn’t tell you if it is the original factory fitted (OEM) one. In all fairness, if the car has a windscreen free of chips, cracks or scratches, the chances are you’ll spend more time looking through it, than at it. Your attention will not be drawn to the glass itself unless there’s a problem with it, and it’s the windscreen that can be hiding those potential issues. One of the most common, is damage caused by a careless windscreen fitter.
A widespread misconception about what the adhesion promoter (in a windscreen bonding kit) is that it is to ‘paint over any scratches’. Even the adhesive manufacturer technical data sheets do not state this, yet this mistaken advice is finding its way into many conversations, “make sure he paints over the scratches!” they will say. Bizarrely, not many people understand that not scratching the paintwork in the first instance is (obviously!) the correct approach. In the image above, it looks as though there’s just a bit of black paint on the paintwork. As innocuous as it might appear, experience has taught me that it is usually there to cover up a mistake. And it will go unnoticed, because the average windscreen fitter (from the cheap, cowboy independent to the ‘insurance approved’ uniformed ‘technician’ representing a national brand) will not see anything untoward about it. I used a fine Scotch-Brite hand pad, and gave it a bit of a tickle…
There are many polyurethane adhesives on the market, some are excellent and some are sold purely on being the cheapest on the market. Sika manufactures the best product I have used, and thus, the only PUR I have used in almost a decade. Quoting directly from their Product Data Sheet is a description of when and where the ‘black primer’ should be used:
Areas of Application
Sika® Primer-206 G+P is used to give improved adhesion in adhesive bonding applications on substrates 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.
This product is suitable for experienced professional users only. Tests with actual substrates and conditions, especially boundary temperature conditions have to be performed to ensure adhesion and material compatibility.
It is not a rust inhibitor, and it certainly is not formulated to cover scratches and protect the metal exposed as a result poor workmanship. By using an appropriately sized chisel and with the correct technique, damage to the pinchweld and surrounding paintwork is minimal, if any at all. If any bare metal is exposed, an appropriate treatment process should be followed. Scratches are caused by carelessness, and the use of inappropriate tools such as long blades, Stanley Knife tools and surgically sharp chisels with removable blades.
Rust remover treatments, etch-primers, paints and polishes have firmly become part of my tool kit over the recent years; the paint damaged cars (from previous installers) have become a very common problem to deal with on a day-to-day basis. In most cases this type of damage will go undetected until the windscreen (or body-glass) is removed.
This is not something that can be ignored with a shrug of the shoulders either; and only after any further corrosion is prevented the original task of replacing the cracked windscreen can be continued.
This carelessness – by the previous installer – added unnecessary time to this job. Shoddy workmanship is unfair on the next installer, and is unquestionably unfair on the car owner especially if it comes at an extra cost. It’s all preventable, and just taking a few extra minutes to do a tidy job can avoid hours of correction work. More images of the job can be found on the Glasstec Facebook page here.
If you have had the windscreen replaced on your Golf, and would like to discuss any issues with it, please use the comments box below.
A good related forum is R32OC.com where there is a thread running on the subject.