DIY Windhsield Damage Repair: Tips For Working With Resin

If a small rock, a piece of hail, or a heavy piece of debris hits your windshield, then it may become damaged. Windshield damage can spread quite quickly due to engine vibrations, temperature changes, and water entering the chip. An immediate or timely repair can stop the damage from spreading and prevent a much more costly windshield replacement. An auto glass repair shop can fix the small point of damage with a resin filler material.

This same type of resin can be purchased at your local auto repair shop and used at home. If you want to attempt the DIY repair at your house, then follow some tips to make sure you do not make mistakes when working with the resin.

Inspect the Damage First

Before you can attempt to fix the chip in your windshield, you should make sure a resin repair is appropriate for the damage. In general, chips can be fixed while damage that contains straight cracks cannot. Cracks tend to spread even after a resin repair, because the ends of the crack are weak points in the glass.

A professional will use a diamond tipped drill to create small holes on either end of the crack to prevent further expansion, but this is not something that an amateur should attempt. Be wary of straight cracks as well as star-shaped damage with four or five arms that expand outward from the middle point. Look for chips like the following when thinking about using resin.

  • Star Chips - These chips feature a central point of damage with four or more cracks protruding from the center. Chip damage extends out from the center and reaches to the ends of the star points. This keeps the cracks contained so they are not at risk of spreading.
  • Bulls-eye Damage - Bulls-eye chips look like a bulls-eye on a target or a dartboard. A small circular chip appears in the middle and concentric circles form outward from the center.
  • BB Chip - The damage is similar to what you would see if a BB were to hit a target. The chip looks big in the center without any surrounding cracks and it is textured.
  • Flower Damage - Flower chips look a lot like flowers with a small central point of damage with four or more crescent shapes protruding out from the center.

Once you identify one of these types of damage, use a magnifying glass to see if the chip extends through the entirety of the glass. Place a white sheet of printer paper behind the chip and turn the magnifying glass about 45 degrees to peer through it at an angle. If the chip appears to be shallow, then continue with the repair. Seek professional assistance if it is deep.  

Deep damage resides within all three layers of the windshield glass. The glass is made up of two pieces of safety glass with a thin layer of vinyl in between. The pieces of the glass are laminated together so the glass cracks and shatters but does not fall away into pieces on impact. The glass also helps to keep the roof of the car from collapsing inward during an accident. Unfortunately, a deep point of damage creates a structural weakness that may prevent the windshield from keeping you safe.

Keep Air Out of the Chip

Resin repair kits absolutely must be used on a clean and dry crack or the water and debris will slowly work its way to the surface of the windshield and destroy the repair. To make sure the chip is ready, squirt some lighter fluid across the crack to force away dirt. The fluid will evaporate afterwards and leave a dry chip behind. Afterwards, make sure you have a glass repair kit with a plastic syringe and a suction cup device.

Attach the syringe to the suction cup and force the cup over the crack so the syringe is centered over the middle of the damage. Once the cup is secured firmly, slowly pull the stopper out of the syringe and hold it in place for 60 seconds. Place your watch on the hood of your car to keep track of time or use a kitchen timer.

This step is extremely important, because a vacuum is created that forces the air out of the chip and the bottom of the syringe. Air bubbles move up through the resin to the top of the syringe so they are not forced into the chip when you press on the plunger. You should press on the plunger after the 60 seconds are up to fill in the chip.


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