To thicken watery nail polish, leave the bottle open in a well-ventilated place, clean the brush, check the polish periodically and put the cap back on when the polish reaches your desired consistency. This takes several days and requires a drinking glass, nail polish remover, a bowl and plastic wrap.
- Remove the cap
Pour 1/4 cup nail polish remover into a small bowl. Remove the cap from the nail polish bottle, and set it in the bowl. Soaking the brush in nail polish remover prevents it from hardening while the nail polish thickens.
- Position the bottle
Lower the open bottle of nail polish into a sturdy drinking glass. Set it in a well-ventilated location where it is unlikely to be disturbed by curious children or pets.
- Clean the brush
Lift the cap out of the nail polish remover, and roll the brush between your fingers. Dunk the bristles back into the remover, lift them out and massage them again. Dunk and rub the brush until it is clean, and then rinse it in warm running water. Pat the brush dry, wrap it loosely in plastic wrap and set it next to the open polish bottle. This reduces your chances of losing the cap.
- Check the bottle
Check the nail polish frequently. Cap the bottle when you are satisfied with the consistency of the polish.