It’s common to have leftover primer after a paint job that you need to store. So you may be wondering how long does paint primer last? Here is the answer to that.
A can of unopened paint primer can last up to 3 years. However, when opened, a can of paint primer that is sealed and stored correctly can last up to 2 years before it goes bad.
But that’s not all. There is more to know about how long paint primer lasts, which digs right into the topic. Let’s dive in.
How Long Does Paint Primer Last After Opening?
Paint primer lasts about two years after opening the container. This is because paint primers usually have similar qualities to regular paint. However, paint primer also has adhesive and bonding chemicals that harden when exposed to outer temperature and air.
So when you open a can of paint primer, it wouldn’t last up to 3 years because the cooler outer temperature and air have been introduced to the container.
Paint primer is used as a base coat before applying the main paint on the surface. Base coats like paint primers are usually designed to dry quickly, so if you open a can of paint primer, the air that goes in is enough to make the primer begin to cure (harden).
Though paint primers don’t usually last more than 2 years after opening the container, the paint can still last long enough if stored properly. This is because paint primers like regular paints are very prone to air, moisture, and heat. These 3 factors can ruin the paint quicker than anything. So if you keep your open paint primer correctly, it can stay good for over 2 years.
The paint primer should be stored correctly in an airtight container. The container should also be kept in a cool and dry room and at room temperature. If all of these storage conditions are kept, then the paint primer can last over 2 years. But what happens after 2 years? Does the primer go bad? Let’s take a closer look.
Does Primer Go Bad?
Paint primer goes bad when the primer is exposed to moisture, heat, cold, or air. Also, air can cause mold to grow in the paint container when the container isn’t sealed correctly, indicating that the primer has gone bad.
Like every other paint type, Paint primer goes bad but not the same way your household groceries go bad. Paint primer goes bad not based on an expiration date but based on the storage conditions of the primer.
Paint primers don’t have any expiration or best before the date indicated on the container of the paint primer. The primer goes bad when it is not stored correctly, and external elements like air, water, and dust get into the container.
When the primer is exposed to external elements, the primer will begin to show signs letting you know that the primer in the can has gone bad. So what are these signs? And how can you tell if paint primer has gone bad? First, let’s take a closer look.
How Can I Tell If My Paint Primer Has Gone Bad?
Paint primers don’t have any expiration date indicated on the container. So to know if the primer has gone bad, you need to check for a few signs. If your paint primer has any of these signs, then it hasn’t gone good.
A Puffed Container
If the primer container is puffed or swollen, that’s the first indication that the primer has gone bad. A puffed container tells you that there are microorganisms present inside the container.
The microorganisms like Bacillus (a bacteria) inside the paint container eat and feed on the primer. After feeding on the primer, these bacteria release gasses that puff or inflate the container.
The gasses being released by the paint-eating bacteria ruins the primer inside the container by contaminating the chemicals in the primer. So a puffed paint primer container indicates that the primer has gone bad.
Related Read: Will Primer Fix Peeling Paint?
If The Primer Is Light
Paint primer, regardless of the type, is usually thick. This is to allow the primer to stick to the surface properly. The thick nature of the primer also helps to improve the adhesive qualities of the surface. So if the primer is light or thin, then chances are the primer has gone bad.
Though paint primer is meant to be thick, it shouldn’t be too thick too. If it is, you should shake or mix the primer with a paint mixer first to loosen the primer a bit.
This is one sign that guarantees that the primer is past its prime. In addition, mold or mildew appears in the paint when moisture and air are introduced into the container.
This happens when the container isn’t well covered or when the container is kept close to water. Then moisture (water) and air get into the paint container. Mold will grow in the container indicating the primer has gone bad. Accompanied with the mold is a very foul smell in the container, and anything that smells foul is bad.
Paint primer should smell like strong chemicals. So if you notice mold and the primer smells like rotten eggs or sour milk, then the primer is bad.
If The Primer Has Cured (Hardened) In The Container
If you notice that the primer has hardened in the container, then the primer has gone bad. Hardened primer means the primer has cured or dried. This type of primer can not be revived because the primer has already hardened no matter what you do, and it will not come back to its original state.
Primer would harden inside the container if the container weren’t properly covered. When you don’t seal the container before storing it, cool air will get in and cause the primer to harden. All paint types, including primers, shouldn’t be exposed to any air at all. The slightest exposure to air will cure the paint and make it unusable.
So when you notice any of these signs, the primer has gone bad. But sometimes, the primer would have gone bad, and you wouldn’t notice any of these signs. So the best way to be sure the primer has gone bad is to:
Conduct A Test
To test the primer, apply a layer or coat of the primer on the surface or a disposable container and see how it dries. You usually can use the primer directly from the container. However, you can also pour some primers into a tray and use a paintbrush to apply it.
So, apply a layer of primer to the needed container. Then see how it dries and the form it takes after drying. The primer should be smooth and fine after it dries. If you notice lumps or an uneven layer, then the primer might have gone bad. A good primer should be easy to apply, and it shouldn’t have any lumps.
If you suspect the primer has gone bad, it’s best not to use it because the primer is the base coat, and if the base coat is ruined, whatever paint you apply on it wouldn’t come out well.
So now you know if the primer is good or bad. But can you use old primer paint? Let’s find out.
Related Read: Does Latex Paint Go Bad?
Can You Use Old Primer Paint?
You can use old primer paint, but only if the primer paint is still in good condition. You will also need to revive the old primer before using it.
Old primer paint works as well as new primer paint. The only factor determining if you can still use the old primer paint is still in good condition. Old primer paint that has been in storage for a while tends not to be good anymore due to the storage conditions.
For example, the can might have dents or holes where air can go in. In addition, the primer itself might have been mold-infested if it was or is exposed to air and moisture. So to know if you can use a can of old primer paint, the first thing to do is to inspect the paint to know if it’s in good condition.
Start by inspecting the container. If you can notice any dents, holes, or if the container wasn’t sealed tightly, then the primer has gone bad. Even the smallest holes are enough to allow air that can damage the primer to get in the container. You should also check the container if it’s puffed or swollen. A puffed container or lid is also an indication that the primer has gone bad.
If the container is good, check the primer. Open the can, and if a strong smell of chemicals greets you, that’s a good sign. But if the primer paint smells foul or vile, it’s a bad sign. Mold is also not a good sign.
The ultimate test to know if the old primer is in good condition is to test it out. If you test it and it comes out as it should, then the old primer can be used. If it doesn’t come out as well as it should, the old primer is past its primer. But even if the old primer can be used, you still need to revive it before using it. So how do we do that? Let’s take a closer look.
Related Read: Can Chalk Paint Go Bad?
How To Revive Old Primer Paint (Made Easy)?
To revive a can of old primer paint, you need to shake the container and then mix the primer thoroughly to eliminate any clumps in the paint primer. Let’s check out how to do this in detail.
1. Open The Container
The first step is to open the container. Then inspect the paint. Old primer paint in good condition will be dull and very thick. If your primer is thick and dull, cover it back tightly.
2. Shake The Container
The next thing is to shake the container. Don’t shake the container too hard, so you don’t spill the primer. Shaking the primer helps to revive the chemical properties of the paint. Since the paint is dull, the chemicals would have separated. So shaking helps to bring the chemicals back together.
3. Mix The Primer
The next step is to mix the primer. It’s best to use a paint mixer or a drill for this task. Paint mixers are effective at mixing paints and primers. You can also adjust the speed of the mixer till the primer is smooth and clump-free.
You can mix the primer manually, but you will need a lot of energy and speed. This is because the primer is usually thick, and since it’s an old primer, it will even be thicker and very difficult to mix. So a paint mixer will be the best bet.
Ensure to mix the primer thoroughly so the chemicals can be revived. The primer should also be smooth, clump-free, and easy to apply. When you have the needed result, you can stop mixing.
4. Add A Solvent
This is usually a last resort. Primers usually don’t need a solvent to revive them, but if the primer doesn’t give the desired results after mixing, you can add a solvent and mix the primer again.
Water-based primers use water as the solvent, so if you are reviving a water-based primer, you can add about a cup of water to the primer and then mix again.
If it’s an oil-based primer, then you can use an acrylic solvent to mix the primer again. This step should revive the primer and make it usable. You can also test the primer on the surface to be sure it’s ready to be used.
Related Read: Is Acrylic Paint Re-Useable?
Can Unopened Paint Primer Go Bad/Expire?
Unopened paint primer can go bad or expire after some time in storage. This is because the chemicals in the primer will begin to lose their form after a while. The container of the primer will also begin to deteriorate after a few months of storage. The deterioration of the container and the chemicals in the primer will make the primer go bad after a few years in storage.
Paint primer can’t remain in good condition forever. After some time, the primer will begin to lose its original form. It can also begin to harden, especially if the primer wasn’t stored properly. The outer cooler temperature will gradually cause the container to become gold until it starts to affect the primer inside.
If the primer is kept in storage for a long time, the bacteria in the paint will become very active and start to eat the paint causing it to go bad quickly. So the best bet is to use the primer paint within the first year of purchase. In that case, you don’t have to worry about it going bad anytime soon.
Related Read: Polyurethane Paint Life Span?
Overall, paint primer lasts about 3 years when unopened but opened primer lasts about 2 years before it goes bad. You can always revive old primer even after 2 years in storage. You just need to ensure the primer is in good condition.