We have touched on the topic of solar coated windshields a couple of times over the years but the issue regarding a white halo appearing around the impact point is one that still has some technicians scratching their heads.
There are two basic types of solar glass and not understanding the difference may affect the outcome of your repair. The first type of solar glass is batch solar glass, which blocks approximately 70% of the Sun’s UV rays but does little to cool the vehicle’s interior. This type of glass is found in most windshields today and is commonly identified by its light green tint, although bronze and grey batch solar glass windshields are also seen.
Often, but not always, batch solar glass windshields are identified under trade names such as Solar, Tint, Solar Green, Solex or Solar Tint. Batch solar glass is made by a process that incorporates the solar-reflective material within the glass itself, and can be repaired with equal success to non-solar, “clear” glass windshields. Because the reflective material is within the glass, a halo will not appear on damaged batch solar glass.
Pittsburgh Glass Works (PGW) produces the second type of solar glass and sells it under the Sungate™ trade name. According to PGW, “The Sungate™ windshield incorporates a multi-layer metal/metal oxide coating on the inboard surface of the outer glass”. When Sungate™ windshields are damaged an air pocket may be formed between the coated layer of glass and the PVB layer. Depending on the extent of the damage, this air pocket may allow air and moisture to come into contact with the coating on the inside surface of the glass, causing a white ring or “halo” to appear.
The halo is caused by the reaction between the air and solar coating. While these windshields are repairable, the milky colored halo will still be visible after the repair is completed. Drilling neither helps nor worsens this effect as it is due to a chemical reaction and not resin flow.
Sungate™ windshields, which reduce infrared energy by 50 percent, are easily identified by the bug in the bottom corner of the windshield and the glass usually has a purplish or orange tint. Always check the bug on a windshield prior to starting a repair and inform customers who have Sungate™ windshields that, while the damage can be repaired and the structural integrity restored, the white ring will not disappear.
Below is a current list of vehicles most commonly equipped with Sungate™ windshields. This list is for PGW windshields only. Keep in mind that just because a vehicle is listed below does not mean that it is equipped with a Sungate™ windshield, so it is always best to identify a Sungate™ windshield by the bug like the one shown above. Other companies like XYG also make solar windshields with a coating on either the number two or number 3 glass surface, so best practice is to always check the bug and inspect for the halo prior to starting a repair. Viewing the windshield through polarized sunglasses may also be helpful in identifying vehicles with the solar coating in the windshield. Through polarized glasses the purplish tint should become very obvious.
For additional information from technicians who have encountered the halo effect, visit the “Ring around the bullseye” discussion at www.windshieldrepairforum.com.