How to repair scratched glass
It's a sunny day and as you look through your window, you notice there is a crack in the glass. Though the crack may not be damaging to the structure and the function of the window, you may be bothered by it. Light scratches can be removed from glass with items you may already have in your home.
Deeper grooves or scratched glass that compromised the function of a windshield or a house window may need to be replaced rather than repaired.
Do the "fingernail test" before you attempt to repair your scratched glass. Drag your fingernail across the surface with the scratch. If your nail catches on the groove, the scratch is most likely too deep to repair at home. You may need to bring your car to the auto shop, buy a new window for your home or just live with a scratch in other glass surfaces that cannot be replaced.
Apply a white, non-gel toothpaste to a light scratch on a glass surface. Make sure the entire scratch is covered liberally with the toothpaste.
Allow the toothpaste to harden. This should only take a few minutes.
Wipe off the toothpaste with a soft cloth. Buff the scratched area in one direction to avoid added new marks to the glass. In most cases, you will see that the scratch is gone once all of the toothpaste has been removed.
Mix together a paste from white vinegar and ground mustard seed to tackle slightly deeper glass scratches. Ground mustard seed is available in the spice aisle of your local supermarket. Start with a tablespoon of the dry mustard and add a few drops of vinegar at a time to avoid making the mixture too wet.
Slather the mustard-and-vinegar paste onto the scratch, allow it to dry and buff off with a cloth.
Buy a glass repair kit for scratches in your car's windshield. Kits of this kind, available at auto parts stores such as AutoZone (see Resources), usually contain some kind of solvent as well as a buffing medium that is safe to use on glass.