The shelf life paint possesses is determined by whether it's oil-based or latex and whether or not it's been opened. You can determine how long your paint will last by its make-up, when you purchased it, and where you've placed it for storage. Here are some tips to help you evaluate how long your paint will last.
Determine whether the product is oil-based or latex-based paint. If the product is oil-based, then the paint, if it's been sealed well. can last an exceptionally long time. Unopened cans can last for as long as a decade and a half. If the paint is latex, then you will have to determine whether it's been subjected to below freezing temperatures, which usually will make the paint ineffective.
Open up the can carefully. Skim off any residue from the top. Stir the paint by lifting the paint up from the bottom of the can while stirring. If the paint does a good job of mixing, then it should last a fairly long time. If it has rust or there are solids formulating on the bottom, it’s time to toss it.
Estimate the paint's current shelf life. If it's been sitting on your shelf for several years and it's oil-based, it should be good for another 10 years if the cover is placed on it tightly. If it's latex, it should last at least another 5 years.