The Case of the Mending Metalized Material
Dear Glass Detective,
Can metalized/athermic windshields with small rock chips be repaired or do they need to be replaced?
Thank you for contacting the Glass Detective with your question as to whether or not what is known as a metalized or athermic windshield can be repaired, or does it have to be replaced? You specifically stated that your windshield has some small rock chips in it and apparently you believe you have a metalized windshield, so you are questioning the viability of performing a simple windshield repair (the chips are small) in hopes of avoiding the full windshield replacement. Good question—thank you for asking it!
The question you have asked is most likely one that will be of interest to others and particularly so in the future. So I am creating two possible questions of my own that they (other readers) may also have when they read this. I have a suspicion that you already know the answer to these questions:
Question #1: What is an athermic or metalized windshield?
This type of windshield, which is becoming more popular with each passing year, is typically referred to as a windshield that has been treated or processed in such a way as to add a very thin reflective coating to one of the two pieces of glass that make up a windshield. For more information on how windshields are made, check out our Where is Auto Glass Made? blog.
This reflective coating acts as a screen/filter and reflects back most of the solar (infrared) radiation that hits the windshield while allowing visible light to pass through the glass. The purpose of the coating that has been added to the glass laminating process is, therefore, primarily intended to reduce radiant heat transmitted into the car by way of the windshield. There are some “side effects” caused by these metalized windshields. One is that they will often interrupt or block radar detectors, tollroad passes, or even remote garage door openers. Typically, metalized windshields have areas that are not treated so that a device of some type will not be blocked by them. These areas may vary from car model or windshield manufacturer to manufacturer.
Question #2: How can I tell if I have a metalized windshield?
Usually, the reflective coatings on a metalized windshield will make the glass appear to be slightly reflective and differing in color (anywhere from a neutral gray color to a bluish/purple color) when compared to a non-treated piece of glass. The various windshield manufacturers do not all use the exact same coating processes, so there will be some variation from manufacturer to manufacturer. If in doubt about what you have for a windshield in your vehicle, see your dealer and they can identify exactly what you have.
Question #3 (YOUR QUESTION): Can a metalized windshield be repaired, or does it need to be replaced?
My opinion (and I recognize that some may disagree) is that any attempt to repair a metalized windshield is certainly appropriate if the repair is in keeping with the Repair of Laminated Auto Glass Standards (ROLAGS). In general, in order to comply with ROLAGS the damage must be less than 14” in length, outside of the driver’s primary viewing area, not extending to the edge of the windshield, and not penetrating to the polyvinyl interlayer. I do not believe that the resins used for windshield repair will negatively impact the coating much if any and because a repair is so much less costly than a complete replacement (a metalized windshield is more costly than a non-treated one) I think it is certainly worth the attempt.
However, if the windshield is an overall heated windshield, a repair should not be attempted. An overall heated windshield is similar to a heated wiper park which keeps the windshield from icing, except that the heat elements run across the entire windshield. Therefore, a repair could cause arching of the current that passes through the elements.
As always, only use certified technicians to perform your repair and/or replacement work. You can find a reputable shop in your area by using the Glass.com search tool. I hope the information provided here is of some value to you and thank you once again for contacting the Glass.com Glass Detective.