Clean the scratch and the area around it with window cleaner. Again, use a soft cloth to wipe off the window cleaner. Make sure the scratched area is sufficiently dry before moving to the next step.
Using the clear nail polish bottle’s brush, carefully apply a thin layer of the clear polish over the scratch. The nail polish should be enough to thoroughly cover the scratch, but not too heavily.
Afterward, carefully remove any excess nail polish with nail polish remover lightly dabbed from a clean cloth.