Remember having a nailpolish that is thick and actually way to old to use, ready to throw away? There is a way to still use them as a nailpolish! That is nail polish thinner!
I've been looking around some forums and on every forum there is a question about how to thin nailpolish. And I don't know were people get some awnsers from but there is one way to thin out your nailpolish and it's not water, olive oil or nail polish remover! Water is going to dry your nailplish out, olive oil is just going to make a oily mess and remover is to remove nail polish, that is not an option either.
I always use thinner from Mavala. But before you're going to use a thinner you have to smell the nail polish first. Because if it smells like a rotten animal you have to throw them away.
When you use a thinner you just have to put a few drops of it in your nail polish, shake it, let it soak in for a few minutes and your nail polish is ready to use!
I use Mavala because that is the only thinner I can get in a store here but there are a lot of different thinners you can buy on webshops. Orly, OPI and Essie have their own thinners.