At some point, we have all experienced this scenario: after a painting project, there is leftover paint that needs to be stored in the garage or basement. Paint can expire within a range of two to fifteen years. To determine its shelf life, consider the type of paint and storage conditions. Let us guide you through this process.
Can Latex Paint Go Bad?
Latex paint can spoil over time, but it usually takes a while. Typically, you can store it for around ten years, with some conditions to consider. The primary factor affecting the shelf life of latex paint is whether the container has been opened. Unused paint tends to last longer. On the other hand, once a can of paint has been opened (and resealed), it tends to deteriorate faster due to potential bacterial growth. Bacteria require specific conditions to thrive, such as darkness, moisture, and warmth, all of which can be found inside a sealed paint can stored in your garage, shed, or basement. If you are using a modern low-VOC or zero-VOC latex paint, it is more susceptible to deterioration from bacterial growth after a few years.
Can Oil-Based Paint Go Bad?
Oil-based paints can go bad, but it will take more than a decade. In fact, an unopened oil-based paint can last up to 15 years, which is five years longer than most latex paint. Unlike modern latex paints, oil-based paints have high VOC counts, which helps preserve the paint for longer. However, this also makes the paint more toxic to people overall.
Can Paint Primer Go Bad?
Primer can go bad just like regular paint, and it has a much shorter shelf life. Most primers have a storage life of two to three years, considerably less time than a paint can.
How to Tell if Paint Has Gone Bad
Regardless of the base type, there are a few key signs that your paint or primer has gone bad:
Odor. Just like rotten food in your refrigerator, there’s usually a harsh smell that accompanies an old can of paint that has gone bad.
Physical changes. You might notice the consistency of your paint has changed. There may be a “skin” on the surface or lumps that won’t stir out. If either of these is present, your paint has most likely expired.
Separated solutions. If your paint has separated into semi-transparent and opaque liquids, try stirring it to see if it comes back together. Wait a few minutes. If your paint reseparates quickly, you’ll know it’s no longer good to use because the solvent and pigment won’t work together to properly stick to the wall.
Because paint is made of solvents and compounds that are potentially harmful, you shouldn’t just throw your old paint in the trash can. Many regional governments have programs set up to help people dispose of their old paint. And if your paint hasn’t expired yet, you can donate it to building charities.
How to Avoid Leftover Paint
Unless you plan to do multiple projects in succession, you’ll probably end up with leftover paint at some point.
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