Why does polish thicken? Nail polish was designed to harden when solvents in the polish evaporate. Each time you open the bottle it allows small amounts to evaporate directly from the bottle. If you leave polish all over the neck of the bottle it won't seal correctly. This means that more solvents will continue to slowly evaporate even if the cover is on. Over time you will find your polish will thicken and become harder to apply. It may even become dry and clump up.

How do I fix thickened polish? The easiest way is to add the solvents back into the polish. You can find polish thinner at your local beauty supply store such as Sally's or at other online stores. Some nail polish manufacturers make thinning products specifically for their own polish line. For example the company Seche sells Thinner Top Coat and Lacquer Restoration Thinner. This product is specially designed to be used with the Seche line of products. Thinning solutions are added directly to the bottle of polish. Sometimes you only need a few drops to bring it back to it's original consistency. Other times you may have to add a dropper full to fix it.

If polish remover thins out polish then why not use it? Polish removers only job is to break down and dissolve polish. This makes it easier to remove from your nails. Adding polish remover to thick polish will temporarily thin it out. But, it will continue to break down the polish components causing other changes to the texture. You might notice that the polish begins to shrink back from the edge of your nail or the cuticle area. It might start to clump up in the bottle. At one time you may have applied one or two coats to cover the nail but now it takes 3 or more. And the color is streaky (is that even a word LOL). It is a quick way to solve the problem but ultimately will cause more.

If you like to use polish keep a bottle of polish thinner on hand. It doesn't cost a lot to buy and will keep your polish applying like a dream.