How to Stop Cracks From Running on a Windshield

by Joshua Smyth
sur la route image by valérie Beunardeau from

Car windshield cracks can be frustrating and a safety hazard. Most windshield cracks start with a small chip from an object hitting it, such as a rock or pebble, while driving. A crack can spread across a windshield, becoming unsafe and requiring immediate replacement. If your windshield has started to crack, it may require professional repair at some point. Not doing so may result in a serious safety risk, as your windshield will be greatly weakened. It is, however, possible to stop cracks from expanding, which could prevent the need to replace the windshield. Applying nail polish or using a windshield repair kit can stop the spread of a windshield crack.

Step 1

Carefully clean the area around the crack and let it dry fully in the sun. If it is not sunny outside, dry it with a hair dryer.

Step 2

Apply clear nail polish to small windshield cracks. Using the brush that came with the polish, work it into the crack, both on the inside and outside. Allow the polish to dry. While not a permanent fix, this will buy some time to shop around for repair jobs and will stop further expansion of the crack.

Purchase a windshield repair kit from an auto supply store. The kits consist of the same resins that repair shops use to fix cracks. Mix the resin with the applicator and work the resin thoroughly into the crack. Clear excess resin and follow the directions on the package for drying.


  • Apply any repairs as soon as possible after the initial chip that starts the crack. If the crack is older than one month, dirt may have worked its way into it, which could make it impossible to repair at home.
  • Avoid applying rain-resistant products to your windshield after it sustains a crack. These are wax-based products that help water roll off the windshield and reduce the need for wipers. The wax will flow into the crack and stop the repair resins from binding to the glass.


  • Large or complex cracks, such as from a large rock or baseball, are unlikely to be repairable. In these cases, replace your windshield as quickly as possible, as it could potentially break, even a minor collision.

Items you will need

  • Windshield repair kit
  • Rag
  • Nail polish

More Articles