Nail Polish Thickening Technique

How to thicken your nail polish:

You simply need to use air, but do it carefully. 
Open up the polish bottle and take out the brush.  Clean the brush with polish remover to prevent it becoming too stiff and put aside. Place the open bottle somewhere safe, where no one can knock it over.

DONT FORGET to put it in a room that you don't spend a lot of time in.  The solvents in the polish will be released in to the air around you and can cause headaches and really isn't very healthy.

Keep it open for a day or two, depending on the climate.