What Causes Bubbling in Car Rear Windshield Films?
3 Answers
Bubbling in car rear windshield films can be attributed to several factors: the use of low-quality adhesive in the bonding or dye layers, lack of attention to detail during the installation process, poor technical skills, incomplete removal of dust from the window affecting the pressure-sensitive adhesive's bonding, or insufficient force applied during the adhesion process. If bubbles appear in the vehicle's window film, the film should be removed and replaced, as there is no way to repair bubbled films. Some vehicle models have rear windshields equipped with heating wires for defrosting and fog control. The heat generated by these wires during operation can be trapped by the solar film adhered to the glass, potentially causing the film to bubble over time. The primary cause of bubbling in rear windshields is the uneven contact surface between the glass and the solar film. Compared to the front windshield and door windows, applying solar film to the rear windshield is more challenging because other windows are flat, allowing for better adhesion with the solar film. It is advisable to choose reputable channels for car film installation. Not only does bubbling affect the vehicle's aesthetics, but it can also impact the driver's mood. Attempting to remove and reapply the film may damage the rear windshield's heating wires, leading to the inability to defrost or defog the window, which poses significant safety hazards.
I've encountered this issue before. There are typically three reasons for bubbling in the rear windshield. The most common one is aging of the interlayer, especially noticeable in older cars. The PVB adhesive film turns yellow and bulges after prolonged UV exposure, creating fish-scale-like bubble clusters. Secondly, installation craftsmanship issues – my friend who runs a modification shop mentioned that if dust isn't thoroughly cleaned or air isn't completely expelled during glass installation, edge bubbling may appear within two years of driving. Another cause is when summer heat causes interior temperatures to skyrocket, softening the adhesive layer while the metal frame expands at a different rate, creating wavy bubbles. These bubbles increasingly obstruct visibility and become particularly dangerous when reversing. For new cars, I recommend avoiding low-quality films. For older vehicles, if the bubbles exceed palm-size, replacement is advisable.
Actually, it's an issue with the adhesive layer in the laminated glass. Unlike the single-layer side windows, the rear windshield has a middle adhesive layer, just like a sandwich filling. This adhesive layer is most vulnerable to three things: prolonged exposure to sunlight making the adhesive brittle and cracked, moisture infiltration causing foggy bubbles, or localized overheating from the defroster wires in winter leading to layer separation. I've personally seen an eight-year-old car where the bubbles had spread into a spider-web pattern. The mechanic said small bubbles might be tolerable, but if they spread to the rearview mirror reflection area, it could cause dangerous glare during night driving.
