How Long Does Paint Last After Opening? – The Shelf-Life of Paint

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Choosing a paint color can be tough. What finish do you want? What color complements the space? Will the texture be distracting? Will you be able to use it again? The latter is a question that can pass through your mind if you’ve found a color that really speaks to you, and knowing that you’ll be able to use that color again in the future can give you a lot of peace of mind. After all, paint tends to lose its viscosity, tone, and texture when it sits on a shelf for too long. This begs the question, how long does paint last after opening? Does it depend on the type of paint? Does it depend on where it’s stored? Let’s have a look at how long paint lasts once it’s been opened and what you can do to make it last a bit longer, if not indefinitely, once you’ve used it.



Can Paint Become Unusable?

Does paint expire? This is a really good question, and the answer is yes! Paint can absolutely become unusable once it has been opened. A sealed can of paint can last over 10 years on a shelf from the date of manufacturing. If the can has been opened, this lifespan can decrease dramatically, and typically cuts the shelf life of the paint in half due to a number of reasons.

Old Paint in Cans

How long does paint last after opening, though? This largely depends on the type of paint you’re using as different types/brands of paint have various additives that are designed to improve their longevity and durability both in the can and once they have been applied to a surface. Typically, synthetic paints like acrylic and enamel can last over 15 years, whereas oil-based and latex-based paints have a shorter lifespan of around nine to 11 years.

These are other types of paint out there that are used for less robust applications like chalk paint powder paint, and because they’re meant to be used for disposable applications, they’re only designed to last around three years before they become really lumpy and essentially unusable. So, does paint expire? The answer is yes, thanks to chemical decomposition.

What is the Shelf-Life of Paint Types


Why Does Paint Expire?

When the paint is made, either oils or acrylic polymers are used to add color to the body of the liquid. These two parts are bound together in the mixing process, but over time these bonds tend to break down thanks to things like atmospheric exposure, the effects of gravity, and the fact that some elements of the mixture are simply not naturally compatible with one another.

Paint Can Expire

If you’ve ever left paint on a shelf for a year or two and suddenly needed to use it, then you’ve probably seen this process of separation first hand. When a paint can is sealed, the ratio of semi-solids and liquids remains constant. However, when a can is opened and exposed to the air and then closed again, this ratio is altered. This imbalance is what causes the paint mixture to break down over time, often starting with the heavier particles sinking to the bottom of the can.


What Factors Affect Paint Shelf Life?

As we mentioned previously, one of the most common factors that affect paint shelf life is whether the can has been opened. Other factors that are important to consider are the temperature and humidity of the environment your paint has been stored in. Paint reacts to temperature changes quickly, and if you’ve ever tried to paint something in the dead of winter or in the heart of summer, you know this.

Temperature Can Affect Paint Shelf-Life

Does paint go bad when exposed to cold temperatures then? Yes, paint needs to be kept in a cool, dry environment once it’s been opened to prolong its shelf life. If not, the paint can and will at least partially freeze over, rendering it useless. Does paint go bad when exposed to exceptionally hot temperatures? Yes, not only does it have the potential to go bad, but depending on the type of paint you’re storing, it could potentially become explosive when exposed to high enough temperatures.



How Do You Know if Paint Has Gone Bad?

Knowing how to store paint to prevent it from going bad is all well and good, but how do you know if your paint has already gone bad? Well, there are a couple of things you can look out for to identify a paint that has already gone bad. Remember to always check the condition of the paint you intend to use before you pour it out into a paint tray as there could be some nasty surprises waiting for you.

One of the easiest ways to tell if your paint has gone bad or not is by the smell. Due to the imbalance of particles and the presence of air in a previously opened can of paint, paint that has gone bad tends to smell like milk that has begun to curdle. Others say that it can smell like rotting eggs or meat with a bad case of freezer burn.

Old Paint Smells Really Bad

If you have somehow managed to miss the smell, or the type of paint you’re using doesn’t produce a smell when it goes bad (like some do) then you should look out for some visual indicators. When the heavier particles in the paint mixture sink to the bottom of the can it can leave the top layer with a thinner consistency that typically has a weaker color to it too.

Check Consistency of Old Paint

The opposite can be true too. If a paint canister is exposed to excessively hot temperatures, it can cause the paint on the surface of the canister to create a thick film. This is essentially a result of the heavier particles being “cooked” together by heat, which can make the paint unusable. When paint has been damaged to this extent even mixing the two parts back together will not salvage it.

How to Tell If Paint is Bad

One indicator that a paint has expired, which tends to point itself out to you instead of you having to look for it, is when paint fails to adhere correctly. This is especially noticeable when using oil-based and acrylic-based paints as they tend to run down surfaces instead of adhering to the surface. If this is the case, you might be able to salvage it. Although, we recommend getting a new batch in the interest of your finish and the overall longevity of your coat.


Can You Use Old Paint?

Can you use old paint? There is a big difference between paint being old and paint being unusable. As you know by now, when the paint is left idle for a long period of time, the heavier particles tend to settle at the bottom of the can while the lighter ones rise to the surface of the mixture. This might seem like the paint is done for, but in reality, all it needs is a little bit of help to be usable again.

How to Use Old Paint

How do you make the paint usable again, though? Well, the best way to go about it is to use a mixing stick (or any stick) to mix the heavier particles and lighter particles back together again. Professional paint shops usually have an automatic mixer that ensures that the paint is thoroughly mixed through, but this isn’t necessarily.



How Long Do Different Paints Last?

As we mentioned previously, there are different paint types that last for different amounts of time due to the nature of their composition. That’s why we’ve detailed some of the most common paint types you’ll encounter and how long they last once they’ve been opened and when they’re left closed for future use.


How Long Does Oil Paint Last?

Oil-based paint is one of the oldest paint types out there. It produces incredible textures, has one of the best consistencies of any paint, and they do a good job of both beautifying and protecting surfaces they’re used on. Oil-based paints often consist of lacquer or natural oil (like linseed or tung oil), which is fused with a coloring agent to achieve those deep, bring colors oil-based paints are known for.

Opened Oil-Based Paint Can Expire

How long does oil-based paint last when they’re unopened? Oil-based paints last the longest out of any paint type when they’re unopened. Their oil-base acts as a natural preservative, which allows the mixture to remain stable for extended periods without any of the bonds dissolving permanently. This longevity translates to once it’s applied to the surface of a workpiece too.

How long do oil-based paints last once they have been opened? Even though oil-based paints can last up to 15 years when closed, this time is cut in half almost instantly once they’re opened. This means that your oil-based paint may only last around eight to ten years once you’ve cracked them open for use.


How Long Does Acrylic Paint Last?

How long does acrylic paint last? In order to understand how long a paint lasts, it’s important to understand what it’s made of. Acrylic paint is made of acrylic polymers, which has had pigments and/or other dying agents suspended in it. There are often other stabilizers like plasticizers and defoamers present in its makeup. These help make acrylic paint high versatile and durable as a surface coating.

Opened Acrylic Paint Can Expire

How long does acrylic paint last when unopened? Well, when left unopened acrylic paint can last for up to 10 years before it begins to break down and cannot be used as intended by the manufacturer. It’s a lot less time than oil-based paints but it’s still pretty long lived by any standard, and this is thanks to all of those synthetic polymers present in its makeup.

How long does acrylic paint last once opened? The cool thing about really high-end acrylic paint is that it can last for nearly as long when opened as it would when unopened. When opened, acrylic paint can last for five to ten years, which is cool considering that most paints that are used for both interior and exterior applications these days are acrylic paints.


How Long Does Latex Paint Last?

Latex paint is pleasant to work with and they ensure that you and your loved ones aren’t exposed to any potentially harmful chemicals while you’re working with them. Even though they’re called latex paints, they’re actually water-based and therefore contain virtually no VOCs (volatile organic compounds), which means they can be used indoors safely.

Check Condition of Paint Before Using

How long does latex paint last when unopened? Latex-based paints typically don’t have loads of additives in them so there aren’t any bonds that can be broken down over time. On the other hand, there aren’t many binders to keep what little elements there are held together either, so depending on the brand latex-based paints can last between six to ten years.

How long does latex paint last once open? This is a tricky question to answer considering that different brands use different ratios of colorant to paint, but generally once opened latex paints can last anywhere between three to five years depending on the type, quality, and conditions in which they are stored.


How Long Does Chalk Paint Last?

Chalk paint is a fairly niche paint type that is primarily used to achieve a rustic or vintage finish. This paint is actually latex based, which has led to it being used in many of the same applications as conventional latex-based paints. Chalk paints are a great way to add character to any space, and they are pretty easy to work with too considering that they require little preparation to use.

How Long Does Opened Chalk Paint Last

How long does chalk paint last when unopened? As we mentioned previously, latex-based paints and acrylic paints are pretty much the same on a chemical level and this means that their longevity is similar too. An unopened can of latex paint can last for roughly six years if stored in conditions that are favorable, but its finish is fragile, so you should test out your latex paint first if it’s been sitting for a while.

How long does chalk paint last once opened? Chalk paint tends to last much longer or much shorter than conventional latex-based paints once it’s been opened. It really does depend on the brand and quality of the paint, but typically once opened chalk paint can last anywhere between two to four years once it’s been exposed to air.


How Long Does Milk Paint Last?

If you’ve never heard of milk paint before, you’re not alone. Milk paint, like oil-based paint, is one of the oldest paint types in the world, but unlike the latter, it hasn’t remained nearly as popular. Milk paint is essentially made of a milk and lime base, which then has pigments suspended in it to add color. In order to make milk paint last longer, a chemical called borax can be added to it.

Can You Store Milk Paint for Re-Use

How long does milk paint last when unopened? This depends on the type of milk paint you’re using, if you’re using the powdered kind, it can last indefinitely until it is activated. Canned milk paint can last for up to a week or more if it’s kept refrigerated at all times. This isn’t the type of paint you’d keep around for more than one use as it tends to go bad quite quickly.

How long does milk paint last once open? Well, not very long. Since milk paint uses milk as its base, it would be the equivalent of keeping a bowl of unpasteurized milk on your kitchen counter in the sunlight. Within one or two days depending on environmental conditions, milk paint will go bad, especially if not refrigerated and left open.



How Do You Store Paint to Make It Last Longer?

There are few things worse than buying a paint that you like, using it, and then storing it for later use only to find that it’s been spoiled. How do you ensure that your paint doesn’t go bad then? Well, the best thing is to store it in a cool dry place with minimal temperature fluctuations. Garages that aren’t insulated are a bad idea, and attics aren’t an option thanks to their elevation.

Badly Stored Paint Will Go Bad

If you have a storage closet or spare room, you should consider these. After all, you like the temperature in your home to be comfortable so your paint should be pretty comfortable too. Secondly, you should ensure that your paint is sealed correctly. When you’re replacing the lid, wipe off any excess paint on the rim of the container to ensure a nice tight seal on the perimeter.

You should also ensure that the lid is on as tight as possible. Use a wooden block placed across the diameter of the container and give it a few good taps with a mallet to ensure that it’s on nice and tight. Inspect the container for any weak points and don’t store it near anything that could potentially puncture it.



Now that you know that paint can become unusable, that all types of paint will eventually expire, what factors affect paint shelf life, and the estimated shelf life of most types of paint, it’s time for you to get out there and put your newfound knowledge to the test. Remember that even though it’s better to have more paint than you need, it can take some work to store it correctly once the job is done.



Frequently Asked Questions


How Long Is Paint Good for in a Can?

How long is paint good for in a can? This depends on the type of paint, the conditions it’s stored in, and whether it’s been opened or not. Commonly used paints like oil and acrylic can last for up to ten years if unopened, and around half that time once they have been exposed to air.


How Long Does Paint Last Unopened?

How long does paint last unopened? This depends on the type of paint and where and how it is being stored. Acrylic paint and oil paint can last for over ten years when unopened, but they need to be stored in an environment with a constant stable temperature for this duration.


Does Paint Expire?

Does paint expire? Yes, paint does expire. Some paints can last for over ten years but eventually, the bonds that bind the pigment, and the main solution will fail which will render the paint unusable. Paint can also become less effective both aesthetically and in its adhesive ability the longer it is left unused.