Many people have half-used cans of paint rattling around their attic or basement that they told themselves they will use someday. More often than not, these paint cans wind up languishing in storage for a long time.

Usually, storing used paint cans is not a problem besides the storage headaches it may cause. However, after some time, the paint becomes unusable, and it is best to throw it away. Here are a few ways you can tell that it is time to get rid of your paint.

General Rules

There are a few guidelines for deciding how long to store cans of paint that may help you decide if your paint is still usable. Unopened cans of oil-based paint can last for as long as 15 years, while sealed cans of water-based paint can last a decade. This longevity only applies if they have been stored properly in a dry place with moderate temperatures.

Once a paint can has been opened, it can usually last only two years, even if it is resealed. Once those two years are up, the paint is usually damaged.

Signs That Your Paint Is Unusable

If you can’t remember when you stored your paint, or you suspect that it may have gone bad before its time is up, there are a few ways that you can test if it still works. First, check the conditions inside the can. If the paint has separated into liquid and solid portions that won’t recombine no matter how much you stir it, then you need to throw it away.

Other signs that the paint has gone bad are a strong, foul odor or signs of mold. You should also scrape the bottom of the can. If the paint has hardened at the bottom, that is a sign that you should not use it.

If the paint looks usable while it is in the can, try painting a test strip on some newspaper or other piece of scrap. Mix the paint properly and paint one swatch across your surface. If you notice lumps or inconsistencies, that means that your paint will not create the look that you are hoping for once you start your project.

Discarding Paint

If you realize that the paint you’ve been storing is no longer usable, you need to dispose of it the proper way. Unfortunately, it’s not as simple as throwing the cans in the trash.

Your paint needs to solidify before you can throw it away. Some people use cat litter. Just mix cat litter into the can, let it dry for a few days until it reaches a mealy consistency, then throw the can away. Others buy paint hardener at the hardware store. Once the paint solidifies, you can scoop it out and recycle the empty can. However, paint hardener does not work for oil-based paints.

Before discarding paint, it’s always a good idea to check with local authorities. Some governments classify oil-based paints as toxic waste and may have special procedures for disposing of them.