Visibility in your vehicle is such a valuable aspect of its daily functional value. Scratched car glass not only impedes visibility but also predisposes your auto glass to other damage. All you need is a little ping from a road pebble to crack a structurally unsound windshield.
Any cracks or chips can lead to spider-webbing and the inevitable need for a complete replacement. I decided to put together a community resource for all auto owners to prolong the life of their vehicles. Please read below for my in-depth analysis of how to remove scratches from car glass quickly and safely.
Assessing the Damage
There are a variety of reasons why your car glass is scratched up. Whether you were tailgating a truck hauling gravel, driving in an ice storm, misusing an orbital polisher, or simply drove through some low hanging trees, it is easy to imagine how glass can accumulate scratches from contact with anything at operating speeds.
The first part of the assessment is determining whether you have laminated or tempered glass. You simply have to look on the lower corner of your driver's side window to see if it says tempered or laminated. Even if the side windows are tempered, the front and rear windows are likely made of a more durable laminated glass.
This is an important distinction when it comes to repairing auto glass. All late-model vehicles produced after September 2017 were required by law to use laminated glass on all panels to prevent people from being thrown from their vehicles in accidents.
The next part of the assessment is assessing whether the scratches are deep or shallow. Deep cracks require a considerable amount of care because any pressure you exert may be enough to shatter the windshield or crack it. This is because the surface tension of tempered safety glass is paramount to the retention of its integrity.
While you may be able to whack your side window clumsily with your elbow; if you use the same force with a small pointed instrument, the whole window will instantly shatter. Laminated glass has reinforced surface tension that requires much more force to shatter but still requires care when it comes to deep scratches.
The best manner of gauging the depth of your auto glass cracks is running your fingernails over the surface. If there is enough bite for your nails to catch, then you will need to a different kind of repair to prevent the scratch from cracking, spreading, spider-webbing, and ultimately failing.
Light Scratch Repair Process
Any repair process is going to require that you thoroughly wash and dry your windows to remove any contaminants that may cause further scratches. This will also allow the repair compound to penetrate without being repelled by grease or waxy residues.
Most of the products that are sold to repair light scratches are similar to rubbing and polishing compounds used to correct the finish of automotive paint. These products come in creams that you apply to a sponge fitting for an orbital polisher. Depending on the brand, you will simply apply the cream to the sponge and then use overlapping circular motions at various RPMs to polish out the fine scratches.
Even if you don't know how to remove scratches from car glass and this is your first time trying, this method is very straightforward and easy. The active ingredient in any quality cream is Cerium Oxide. Cerium Oxide penetrates into the micropores of the scratches and bonds to the material to restore the surface and seal the repair.
3M makes a reliable product that is premixed and ready to apply. If you are doing the repair by hand, you will simply apply the 3M polishing compound to the damaged glass itself and use a cloth to work at it. Never apply too much pressure in any case because the Cerium Oxide should do all the work if you move it around.
Although the 3M product is nothing more than Cerium Oxide mixed with the ideal volume of water to form a paste, you may need to continue wetting the surface with a spray bottle. If an orbital tool runs too dry, it can overheat and crack the glass. Make sure the surface is lubricated and that you are letting the circular motion and compound do the work without trying to burn a hole in the windshield.
When the repair is finished, simply wash the auto glass clean and check the repair every so often to ensure that the area does not reform any scratches or cracks.
Deep Scratch Repair Process
When it comes to repairing those deep scratches that jeopardize the value of your vehicle, quality auto glass resins are the weapon of choice. If you fail to repair deep scratches they can crack and force you to replace a windshield. Replacing windshields is problematic because cross-contamination of dissimilar metals can lead to rust cancer or white powder deterioration of aluminum.
Even if your vehicle is not made of dissimilar metals such as aluminum and steel, the risks of forming a leak are greater in a reinstalled windshield. These leaks can lead to electrical gremlins that can send any late-model vehicle to the boneyard. However, if you live in Tracy California or surrounding areas, we guarantee all of our work for as long as you own your vehicle - so you don’t have to worry.
Resins come in a variety of viscosity ratings. A resin with a viscosity of 25 cps is like water. A resin that is rated at 1,600 cps is thick like honey.
Unfortunately, it’s difficult for consumers to find the high-viscosity industrial grade auto glass repair resins. The low-viscosity resins that come in kits may be sufficient enough for a deep scratch but not good enough to retain the integrity of cracked glass. This is why it is better to have a professional repair deeper scratches if they’re isolated.
Typically, the resin is applied with a number of special tools such as injectors and vacuums to set the ideal volume of resin in the surface before hardening. A UV light is used to cure and harden the resin after the surface is adequately sealed. When the repair is done correctly, you won't be able to tell that there was ever any damage at all.
Applying a commercial kit resin is little different than using nail polish or superglue. You have to guesstimate the ideal volume of resin by applying it slowly and making sure to remove any air bubbles. You then use plastic sheets to firmly smooth out the surface.
You let it cure in the sun or under a UV light for 10-30 minutes and then scrape off the extra resin compound with the included razor blade. It is said to be an art form that takes some practice to get perfect results. Although these compounds are used for cracks, a deep scratch may be millimeters away from forming a crack so you should consult a professional if you’re unsure.
If you have light scratches, the 3M Cerium Oxide compound buffed in with a rotary tool is probably about as easy as it gets. If your scratches are deep, you may have to weigh the consequences of doing it yourself against the convenience and certainty of a professional repair. While the resin repairs can always be corrected by a professional if your Rain-X kit fails, your comprehensive auto insurance may cover the damage without cost on deeper scratches to prevent a claim for broken auto glass.