How to Keep Nail Polish Thin. Bottles of nail polish can last for a very long time. When you have many different colors, it may be months before you use any single bottle. Keeping the nail polish thin enough to use can be a challenge. Rather than throw away those thick, messy bottles of nail polish, try some of these tips to keep each color fresh and usable.

Put four or five drops of nail polish thinner in the bottle when the polish becomes too thick to apply evenly. Nail polish remover will not work for this purpose. There should be a nice, small drop of nail polish on the end of the brush when it is thin enough.

Store nail polish in a cool, dry place. Keeping nail polish in the refrigerator, which many women seem to do, actually makes it harder and thicker. Even when it is removed and allowed to return to room temperature, the chemicals may be so changed that you will not get a nice, even coat from the nail polish.

Toss nail polish after about two years. Be realistic about the longevity of your favorite colors. While a certain color may go out of fashion for a few years, don't hang onto it thinking it will be back in style some day. Nail polish is unusable after some time.

Handle your bottles of nail polish gently. Shaking the various colors before applying only make bubbles in the polish and can make it more difficult to apply. The thicker coloring that settles in the bottom of the bottle can be mixed by holding the bottle between your hands and gently massaging it. Turn the bottle upside down once, then upright.