How Long Does Paint Last? 6 Signs It's Time to Toss

One of the best ways to reduce the cost of a painting project is to reuse leftover paint from previous jobs around the house. As long as paint is stored in a cool, dry location using an appropriate container that has been properly sealed, it can generally last several years after being opened, so even if there aren't any immediate plans to paint, it's a good idea to store extra paint instead of disposing of it.

However, paint doesn't last forever. The contents can begin to dry, the ingredients can separate, and the paint can become chunky and sour-smelling. Rust and corrosion on the can are signs that the paint is no longer good. Similarly, there could be mold or mildew growth inside the paint can that indicates it's time to toss the old paint. Use this guide to learn six signs of bad paint and discover how long paint lasts.

How Long Does Paint Last?

The exact amount of time that paint can last depends on a few factors, including whether the can has been opened, the type of paint, and the storage method. Unopened cans of paint will generally last longer than opened cans of paint because they have not been exposed to dust, debris, and air.

Open cans of paint don't last quite as long, but if the can is sealed after painting and stored in a cool, dry location, like a heated garage or a basement, the paint can last for years. On average, a can of paint lasts about 10 years before it needs to be tossed, though some paint products may last up to 15 years.

Paint Types

The lifespan of paint depends heavily on the type of paint.

Water-Based Latex Paint

One of the most common options for interior painting projects is water-based latex paint. This type of paint uses less preservatives than oil-based paint, so it doesn't last as long. DIYers can save water-based latex for about 2 to 10 years, depending on how the paint is stored. To improve the life of the paint, avoid storing it in an uninsulated shed, garage, or similar area that is susceptible to the summer heat and freezing winter temperatures.

Acrylic Paint

Acrylic paint isn't as susceptible to freezing as water-based latex paint, but it will dry up quicker if exposed to open air, so it's important to ensure acrylic paint cans are properly sealed before storing them. Expect acrylic paint to last about 2 to 10 years as long as it is kept in a sealed container and properly stored.

Oil-Based Paint

The paint type with the longest shelf life is oil-based paint. This type of paint can last for up to 15 years when it is stored in a cool, dry location. Just make sure that the paint can is properly sealed after each use. It's worth noting that oil-based paints can typically be opened and resealed several times over the years, though this may reduce the life of the paint from 15 years to 10 years.

Limewash Paint

Limewash paint is generally used on exterior masonry surfaces, like an exposed brick wall. The paint can brighten the intended surface, giving it a renewed look. This type of paint will typically last 5 to 10 years. The reason limewash paint tends to last longer than water-based latex or acrylic paint is that it is only made with lime, water, and sometimes a color pigment.

Chalk-Style Paint

An eco-friendly option, chalk-style paint is a great way to update a home without negatively impacting the environment. However, this paint requires a top coat to seal the painted surface, otherwise, it can be susceptible to moisture. When reusing chalk-style paint, you may find that the paint has dried up, but in some cases, this can be fixed by mixing in some water. Generally, chalk-style paint lasts just 1 to 5 years, so it's important to use it before it goes bad.

Milk Paint

Another environmentally safe product is milk paint. This type of paint is also non-toxic, making it an ideal choice for kids' furniture and toys. DIYers can make their own milk-paint products using powdered milk, though this concoction will usually only last 1 to 7 days. Alternatively, you can purchase premixed milk paint, which can last between 1 to 2 years as long as the paint is stored in a sealed container and kept in a refrigerated space.

6 Signs Paint Has Expired

1. Chunky Consistency

It's good to get in the habit of stirring paint before using it. Even if it's a new can of paint, using a stir stick is a great way to ensure the ingredients are properly mixed. When you grab an old can of paint from the basement or garage, use a stir stick to mix the contents. Old paint is likely to separate. This is also a good opportunity to check the consistency of the paint. If after stirring the paint the consistency is chunky, lumpy, or has a cottage cheese-like texture, the paint has expired.

2. Sour Smell

When opening an old paint can, one of the first things to check is the smell. Few people enjoy the chemical scent of acrylic or oil-based paints, but a quick sniff can help identify if the paint is still usable. Expired paint takes on a sour, rancid smell that is easy to distinguish from a typical paint smell. If it smells rotten when you open the paint can, it's time to toss the old paint.

3. Skinning

When a fine layer of dry paint forms a film on top of liquid paint, this is known as skinning. Minor skinning isn't usually a problem. The DIYer can simply remove the dried layer, then mix the paint before using. However, thicker layers can leave dried particles in the paint, which can affect the appearance of the painted surface. It's recommended to toss the can of paint if there is a significant amount of skinning.

4. Ingredient Separation

One of the most frequent signs that paint has gone unused for too long is ingredient separation. The color pigment will often settle at the bottom, leaving the chemical ingredients on top. Typically, the paint can be mixed up in a home improvement store with a professional paint mixer, or you can try recombining the ingredients manually with a stir stick. However, the older the paint gets, the less successful these efforts will be, so it might be time to invest in a new can of paint if you notice that separated ingredients aren't mixing properly.

5. Mold or Mildew Growth

While one goal of closing a paint can is to keep the paint from spilling, it's also to prevent air, dust, dirt, mold, and mildew from entering the can. For this reason, it's important to ensure the can is properly sealed, not just closed. If the paint can is not properly sealed, mold and mildew can start to grow inside the can, spreading along the inside walls and across the top of the liquid paint. It's time to discard the paint if you find mold or mildew growing inside the can.

6. Rust or Corrosion

Another sign that paint has expired is the current state of the can. A badly rusted or corroded paint can indicates that the paint has not been stored in a safe, dry location. Given the condition of the can, there is a good chance the paint inside is expired. However, the only way to know for sure is to open the can and check the paint. If the paint seems to be fine, it's recommended to pour the paint into a more suitable container for proper storage.

How to Make Paint Last Longer

Proper Storage

The area where the paint can will be stored is one of the most important considerations. Paint cans are not insulated, so the contents can easily be affected by temperature. With this in mind, it isn't a good idea to store paint in a location that is exposed to extreme temperature fluctuations, such as an uninsulated shed or in a deck storage box. Instead, most types of paint should be stored in a cool, dry location, like the basement. One exception to this is milk paint, which should be refrigerated to ensure it lasts as long as possible.

Check for an Airtight Seal

Sealing the paint can or container can help to prevent the paint from drying out. This airtight seal also reduces the risk of mold and mildew growth. The best way to create an airtight seal in the paint can is to close the lid, then turn the paint can upside down, so the liquid paint is pressed against the inside of the lid.

Avoid Contaminating the Paint

Unfortunately, mold and mildew may still spread inside the paint can, even if it has an airtight seal. This can occur if the paint has been contaminated during use. To prevent adding bacteria or mold to the paint, always pour from the paint can into a tray or cup before painting, then dispose of any remaining paint instead of pouring it back into the can. Additionally, avoid dipping the brush or roller directly into the can or leaving the lid off the can when the paint is not in use.