Windshield repair is a specialized job that many professional centers undertake. A home repair kit will not produce as good a result as a professional job, but it is a cheap option good enough for minor damage. This article will teach you how to assess the risks and repair your windshield if it is the best action to take.
Part 1 of 3: Deciding between repairing the windshield or replacing it
Step 1. Review the terms of the insurance and repair contract
The cost of repair or a total replacement varies significantly depending on your location, your insurance, and the type of windshield. If you don't have any insurance, a visit to an auto glass repair shop might surprise you. A professional repair is more expensive than a home kit, but the result can be considerably less visible.
In Florida, Arizona, Kentucky, South Carolina, and Massachusetts, comprehensive auto insurance will cover the entire cost of repair or replacement. If you live in another state or country, or if your car insurance is not comprehensive, you may have to pay for part or all of the repair yourself
Step 2. Look for damage near the edge of the windshield
Cracks or fissures in the edge can compromise the structure of the windshield. Even after repair, this damage could be a major safety concern. Instead of repairing your windshield, have it replaced.
Step 3. Consider the driver's line of sight
Damage directly to the driver's line of sight can interfere with driving the car, even after repair. The most dangerous area is a 12-inch (30 cm) wide piece of glass centered in front of the steering wheel and extending the height of the windshield wipers. If this area is damaged, it is recommended to replace the windshield. You can decide to carry out the repair and then judge the visibility.
In this area, two damaged spots separated by a distance of 10 cm (4 inches) indicate the need for a replacement. This pattern of damage can create a blind spot for the driver, thus obscuring the line of sight in both eyes
Step 4. Measure the length of the crack
Thanks to modern techniques, most cracks smaller than 15 cm (6 inches) can be repaired at home. For cracks longer than 18 inches (46 cm), consult a professional first and only repair them yourself if they think it is safe. Any longer crack requires a total windshield replacement.
If there are two or more cracks, take the car to an auto glass repair shop and ask if it can be repaired. Typically three long cracks indicate the need for a total replacement
Step 5. Examine the cracks and dents
Impact damage may or may not be repairable. This depends on its shape and size:
- Circular or semicircular “bullseye” cracks should be less than 2.5 cm (1 inch) in diameter.
- A “star break,” or an impact point with short cracks extending outward, must have cracks that fit within a circle that is 3 inches (7.5 cm) wide.
- Other shaped cracks must fit within a 2-inch (5 cm) circle, not counting outward-extending cracks.
Step 6. Check the depth of all damage
Windshields are made with two layers of glass and a layer of plastic between them. If the crack extends beyond the outer shell and into the plastic or inner shell, replace the entire windshield.
Windshields damaged from the inside are rare and even a professional might not be sure how to evaluate them. For safety reasons, it is usually best to replace the windshield
Part 2 of 3: Prepare the windshield
Step 1. Purchase a bridge type windshield repair kit
You can purchase a windshield repair kit at an auto parts store, department store, or online. Ideally, choose one that contains a “bridge type” injector that attaches to the glass using suction cups. These are more stable than syringe injectors. The injector should also include a suction system to remove air from the cracks while you repair them.
Almost all repair kits have similar components and work the same way; however, it is a good idea to read the instructions that come with the kit to see if you have any special requirements
Step 2. Plan to use sunlight or an ultraviolet lamp
You will fill the crack with a resin that needs to be cured with UV light. If you can't wait for a sunny day, you will need a UV light to finish the repair.
If your car is parked in sunlight, shade the windshield until you're ready to cure. This will allow you to proceed at a calm pace
Step 3. Remove the broken glass
Use a thin metal object to gently remove small glass shards from the impact points. For this purpose, some kits include a glass extractor.
Wear gloves when handling broken glass
Step 4. Clean and dry the windshield
The windshield must be completely dry before starting. If there is a little dust in the cracks (which is usually the case), clean it with a vacuum cleaner or a small amount of acetone or lighter fluid. If the glass is wet, dry it with a tumble dryer.
Part 3 of 3: Repair the damage
Step 1. Prepare the injector
Take a few minutes to familiarize yourself with how the injector works. There are many different models, but most are easy to use if you follow the instructions. Check the following:
- Identify the syringe or cylinder in which the resin is loaded and the cap or rubber ring that is used for the closure.
- Find the marker or bolt used to adjust the pressure by placing the injector on or away from the windshield.
- Review the instructions on how to operate the injector. A syringe injector has a single piston, but some bridge injectors may have a unique mechanism.
Step 2. Cut a small hole if necessary
This is the step that poses the greatest risk of further damaging the windshield. Fortunately, this is only necessary if you are repairing a long crack that does not end in a circular or semi-circular hole, or if you are filling a small “star break” where no piece of glass is missing.
- To cut the hole, place a glass extractor (or sturdy needle) into the star-shaped crack or the end of a crack. Cut gently with the suction cup removal tool (or any solid object) until a small piece is removed.
- In some cases, you will need to drill into the hole before cutting it. For home repairs, never pierce more than ¼ of the glass. It may be best to hire a professional if you can't cut a hole without a drill.
Step 3. Load the resin into the injector
Most repair kits come with two types of resin. One is designed to fill cracks and the other to fill cracks. Fill the injector with the resin necessary for your repairs following the instructions in the kit. In most cases, you will only need a few drops of resin.
Step 4. Put the injector in position to repair a crack
Coat the suction cups with a thick layer of lubricant so they can move across the windshield. Position the suction cups so that the tip of the injector is over the hole at the end of the fissure. Adjust it until it gently presses on the glass.
- If your kit does not include lubricant, use petroleum wax (petroleum jelly).
- If you are using a syringe injector without suction cups, just hold it at the end of the crack.
Step 5. Apply the resin at the beginning of the crack
Move the injector through the first 2 to 3 inches (5 to 7.5 cm) of the crack. Apply resin following the instructions on the model. Generally, this involves retracting the air with a piston or some other suction mechanism and then releasing it to push the resin into the fissure. Roll it back and forth across the fissure, making sure to introduce the resin.
If the resin does not enter the crack, flex the glass gently with your thumb as you apply it. This should only be necessary at the beginning
Step 6. Seal the rest of the fissure
Move the injector along the entire length of the fissure. When you are sure that the resin has entered the crack, you should be able to seal the crack with a slow motion.
Note that until now the crack will still be visible
Step 7. Fill the cracks and dents with a thicker resin
Fill the injector with a resin for filling holes or the type that your kit includes to fill dents. If you're using a bridge-type injector, lightly lubricate the suction cups so that they adhere firmly to the glass. Place the tip of the injector over the crack and use the vacuum or pressure system until the resin fills the dent completely.
- Syringe injector kits usually include a separate suction cup that you can place over the dent and that has a hole to insert the syringe.
- Remember that in star-shaped breaks where no piece of glass is missing, you must first cut with a glass extractor.
- If the injector contains a different type of resin, clean it first.
Step 8. Cover all the resin with a curing tape
These are also called curing strips or tabs when sold in different sizes. This tape secures the resin during cure, preventing it from overflowing out of the crack or hole.
- You may need a suction cup removal tool or razor blade to remove the injector.
- Never use plastic wrap or other substances that are not specifically designed for this purpose. Some of them block UV light and therefore stop the curing process indefinitely.
Step 9. Let the resin cure
Leave the repaired areas in direct sunlight or place them under UV light until they heal. This can take between 30 and 120 minutes, depending on the brand and intensity of the UV lamp or sunlight conditions. Review the instructions for your product and let it dry longer than indicated.
Driving a car or opening its doors before the resin is fully cured increases the likelihood of cracking lengthening
Step 10. Scrape off excess resin
Remove the curing stripes. Scrape the resin off the surface of the windshield using a razor blade. Wipe off excess resin until the windshield is smooth. If the windshield is cloudy or if the crack is still visible enough to interfere with driving the car, you may need to re-cure it with a special refinish resin. When you're done, clean with a cloth and glass cleaner.