I don't know about you, but I love nail polish. I buy a new bottle at least every 3 months. I haven't counted lately, but I might have at least 10 bottles of nail polish. Like I said, I love nail polish. I also love tips that will help me keep my nail polish - and my bottles - looking good!
Nail polish too thick?
ORLY has a great thinner, but it can be quite expensive.
One way you can thin out thick nail polish is to use nail polish thinner. Now, sometimes it works and sometimes it doesn't. I guess it really depends on what brand you get. I don't use thinner because I really don't come across thick nail polish unless the polish is more than 3 years old.
I sometimes use a drop of non-acetone nail polish remover. Now, I'm not saying to do this -- it might not work for you. But a drop in a solid color polish helps thin it out just enough for me to use it. If you do try this, I suggest using it on an old polish (that rarely gets used) and NEVER use it on shimmer/glitter/gel/hologram polishes. The remover will change almost everything about it.
Nail polish too thin?
I recently came upon a really thin nail polish but in all honesty, it was a super cheap polish and you apparently get what you pay for. Remember when you were in elementary school and you got to use water colors? Remember how watery the paint would get? It was like trying to put that on my nails.
One way to thicken really thin nail polish is to keep the lid off for 10-15 minutes, stirring about every 2 minutes. Close the bottle, and roll between your hands. That should help thicken it.
Is your bottle sticky or caked with polish?
Lid stuck on the bottle?
You can either drop the bottle into a cup filled with hot water for a few minutes. If it doesn't work, repeat until it does. Make sure that You can also wrap a rubber band (the thicker the better) around the lid, and try to create some traction.
Another idea, but one that is really off-the-wall, is to use one of those rubber jar gripper thingies. Sometimes it works, and sometimes it doesn't.
Remember - trial and error! What works for you might not work for some and what works for some might not work for you!