Today’s car windshields are significantly different from the tempered glass windshields of the 20th century. While tempered glass was able to provide a material that’s harder and stronger than pure glass, it had one shortcoming – it shattered easily. Laminated glass that makes today’s windshields came to overcome this shortcoming. It bends slightly upon impact and this flexibility prevents shattering. Thus, laminated glass is so far the safest option for windshield manufacturing, among other auto glass applications. In fact, in the U.S and many other countries, the law requires that all cars are fitted with laminated windshields.
What is laminated glass?
Laminated glass is a type of composites. To make a composite, two or more materials are combined with an aim of maximizing their useful properties and minimizing their individual weaknesses. Composites can be laminated materials, particle composites, or fiber composites. Composites are designed with a specific application in mind. Laminated glass windshields are made of laminated materials. Most of them are manufactured using Glass Reinforced Plastic (GRP) which is one of the oldest and most popular composites.
Making laminated glass windscreen
The making of different composites follows an almost similar procedure but using different materials. Generally, one material is tightly bound into another material to make the resultant material more damage resistant. During the manufacturing process of most current-day windscreens, two sheets of toughened and cleaned glass are bonded together with a clear plastic sheet. The adhesive forces between the glass and plastic and the help of heat and pressure from the special oven used in the manufacturing process assist to create a laminate that’s highly resistant to tearing or breaking.
In the making of the windscreen, a number of requirements need to be met. The laminate needs to retain long-time clarity and provide reliable structural support to the car’s roof. It should be strong and shatter-resistant so that the windshield stands the least chances of shattering in the event of an accident.
Repairing a laminated glass windscreen
Using laminates comes with some implications and challenges. As expected, the cost of a laminated glass windscreen is higher than that made of pure glass. Maintaining the windscreen is another major concern to owners and auto glass repair professionals. Advanced methods, equipment, and chemicals are involved in the windshield repair and replacement procedures.
In a typical laminated glass windshield repair, the damaged area is first cleaned and tidied. All the air in the chip or crack is sucked out with a vacuum and a clear resin is injected. The vacuum is then reversed to force the resin to fill the area. The repaired area is covered with a special film and a ultra-violet light is applied to harden the resin. The surface of the glass is then cleaned and polished and the car is ready for a safe run.
The windshield repair resin
The resin used in windshield repair is an important component of the laminated glass windshield repair kit. A resin is an epoxy – it’s used as a bonding agent. There are different resins in the market but not all can be used on laminated windshields. The depth of the damage also influences the choice of resin to be used. Different resins have different viscosity. The viscosity of a resin is measured in cps (centipoise) and is indicated on the resin package. Low cps means less viscosity or little thickness while a high cps means the resin is highly viscous or thick. The deeper the windshield damage, the more viscous the resin should be.
Principles of repairing laminated glass damage repair
- The resin should not only have good viscosity but also the ability to leave the windshield clear. There are some resins that leave a yellowing effect on the windshield.
- The required special resin should be cured with ultraviolet rays to ensure that the windshield material is brought back to its initial resistance.
- The resin should be safe to use; for the safety of the technician
- The technician must be trained and certified.
The windshield provides unmatched safety to the car’s users. Proper installation and repairs should be done by a reliable auto glass professional. The lack of proper tools and chemicals result to incorrect repairs that further reduce the strength and integrity of the cracked or chipped windshield. Therefore, the importance of applying the right resin when doing repairs to laminated glass windshields cannot be overstated.