With stones flying in all directions, windscreen damage is an everyday occurrence. But sometimes it can be fixed without the expense of replacing the entire screen.
I’M willing to bet that every motorist will experience a damaged windscreen caused by flying debris (usually thrown up by trucks) at least once. Two years ago, I had both the windscreen and the glass roof of my long-term Peugeot 3008 replaced due to just such an incident. While replacement is the order of the day, sometimes repairs are successful.
WHAT CAN BE FIXED?
Only if a hole can be drilled through the first layer at the centre of the chip is the “fix” viable. Short cracks can be attempted by drilling a small hole at the fracture tip to relieve the high stress concentration, but remember that there is no guarantee. Generally, only the bull’s eye type of chip is successful. Take note that a perfectly invisible repair is highly unlikely. The best you can expect is a reduction of visible damage of around 80%.
Cracks that spread cannot be repaired because they grow with time (and stress) and ultimately lead to total failure. Insurers generally do not allow repairs up to 110 mm either side of the driver’s line of sight (steering-wheel centre). Also, cracks longer than 150 mm and chip damage over 25 mm in diameter. Side windows can’t be repaired because they aren’t made from laminated glass layers but toughened glass.
WINDSCREEN TEST CASE
We popped in at Glasfit in Cape Town’s Montague Gardens in the hope that the stone chip in front of the driver’s seat of our long-term Mitsubishi Triton was repairable. Manager Johnny Cornelissen gave us the run-down of the process.
Although he advised that the Triton’s chip was too complex to guarantee success, he agreed to run it as a test case, the uncertainty due to multiple small glass chips at the centre of the damage which would prevent full penetration of the resin.
HOW THE REPAIR WORKS
Glasfit technician Iqbal Khan first cleaned the area of all dirt and grease. He then attached a vacuum pump to the chip, which sucked air from the cracks. Using the same equipment, Vitrafix liquid resin was introduced into the voids under pressure. An ultraviolet lamp was then placed over the area to harden the resin and, finally, the surface was scraped clean with a Stanley blade to remove any unevenness in the resin. The resin must be flexible, return lost strength to the glass and cope with extreme heat and cold. Some backyard repairers may use cheaper liquid glue that will turn yellow after about a year.
HOW MUCH DOES WINDSCREEN REPAIR COST?
To repair a windscreen will cost from R200 to R300 depending on the company used and complexity of the damage. Insurers will usually cover the full cost of such repairs.
THE DIY WINDSCREEN REPAIR ROUTE
Specialist manufacturers sell complete kits containing all equipment required, plus a training DVD if you wish to start your own repair business.
DID YOU KNOW?
- A windscreen contributes roughly 35% to the roof strength of a car. In other words, the glass forms a part of the monocoque structure.
- Panoramic glass roofs are also made from laminated glass.
- Roadworthy test centres will fail your car if there is a chip in front of the driver (in an approximately 300 mm wide section).
- A windscreen is actually two sheets of glass held together with a vinyl interlayer, usually polyvinyl butyral (PVB). This prevents break-up of the glass when damaged.
- Laminated glass reflects 99% of ultraviolet light. All damaged glass is now recycled. It’s an expensive but necessary process.
Thanks to Johnny Cornelissen from Glasfit Montague Gardens for his assistance. Contact Glasfit on 0860 123 423 or visit www.glasfit.com