Posted on October 31st, 2022

Reusing old paint is a great way to go green and reduce expenses on your next DIY project. But does paint go bad? Before you dive into a project, it’s a good idea to check to make sure your paint hasn’t gone bad while it’s been in storage. Improperly stored paint can spoil or be prone to quicker peeling, so you can’t simply grab a can off the shelf and get started before you’ve inspected it carefully.

We’ll clue you in on everything you need to know if you suspect you might be dealing with a batch of house paint that’s past its prime. Let’s take a look at how long is paint good for, why it goes bad and what to do if it’s over the hill.

Use the above ranges and the following questions to decide whether it’s time to buy new paint:

Was the container of paint already opened?
How well was the container sealed?
Where has it been stored?
At what temperature has the paint been stored?

What Are the Different Types of Paint?

While all those cans you’ve got stacked up in storage may look the same, it’s important to understand that there are big differences among paint types that affect how long they’re good for. Latex, oil-based acrylic, chalk and milk paint are different substances with their own expiration dates.

Latex Paint

Latex paint is a versatile, water-based paint that can be used on interior or exterior jobs. Since it’s mostly made up of water, latex paint contains fewer toxins than oil-based paint, but it’s much more susceptible to freezing. When stored correctly, latex paint can last between 2 and 10 years.

If you live in a cold climate, it’s best not to store latex paint in a garage or storage space that’s not climate-controlled, since repeated freeze/thaw cycles can make your paint lumpy. Minor lumps can be gently stirred out with a paint stick, but if the problem is severe, you likely won’t be able to achieve an even coat of paint on your walls. In a case like this, it’s time to dispose of the latex paint and buy a fresh can.

Oil-Based Acrylic Paint

Oil-based paint is a beautiful, thick paint that spreads easily on just about any surface. But it’s more likely to contain volatile organic compounds (VOCs) than its water-based peers—and since it’s oil-based, this type of paint is much more likely to separate when it spends a long time on the shelf.

When properly sealed in a container, oil-based paint boasts the longest shelf life of any type of paint. A can that’s been opened and properly resealed may easily last a decade in storage, while unopened paint can last up to 15 years. However, a word of caution: When oil-based paint is left partially opened, it dries out rather quickly. And as it dries, it releases toxic fumes that could cause a fire. So it’s wise to be extra cautious when it comes to storing acrylic paint.

If your oil-based paint has separated but looks and smells fine otherwise, a simple stir will have you ready to go in no time.

Chalk Paint

Super thick and smooth, chalk paint is the ideal medium for small projects like furniture or doors. It dries to a beautiful matte finish for a modern look or can be layered, distressed or sanded.

While chalk paint can last from 1 to 5 years if stored properly, chalk paint will dry up much faster than that if left exposed to air. If your chalk paint has thickened considerably since last use, know that you can thin it with water if you’d like to use it again.

Milk Paint

The paint with the shortest shelf life of all is milk paint. This thick paint is made with absolutely no harmful chemicals, making it ideal for jobs where children or even animals are involved. But the added milk proteins in this type of paint give it a shelf life of just a few days to a week once it’s mixed.

Pre-mixed varieties that come in a tightly sealed can will last longer and can last up to a year if sealed properly. Keep in mind that milk paint can and should be refrigerated if you have to take a break in the middle of your paint job.

How to Tell If Paint Has Gone Bad

Chunky, lumpy, or smelly—all of these (unattractive) descriptors are indications that your paint may have started to go bad. Repeated freeze and thaw cycles can cause paint to get lumpy, which means you likely won’t get that smooth, beautiful finish you’re hoping for when you paint your walls.

Rancid odors in paint likely indicate bacterial growth, so you should never use paint that smells bad. Trust us—if it smells bad in the can, it will smell bad on your walls, so it’s best to skip this paint and buy a fresh can.

In general, it’s okay to use paint that has separated. Simply turn the can upside down a few times, give it a gentle stir or use a paint stick to reincorporate the paint. If you’re unsure whether the paint can be used or not, take a trip to the paint store, where you can obtain a professional’s opinion.

Original Post: How Long Does Paint Last?