Does Water-Based Paint Expire?

We all have, at some point, decided to take up a DIY painting project for which we bought paint and now have leftovers. Some time has gone by, and the remaining paint has been sitting at your place for a while. Now, you are wondering– does water-based paint expire?

Yes, a can of unopened water-based paint can expire. If stored correctly these paints stay in a good and usable condition for up to ten years. However, having crossed the ten-year mark, the paint may start changing its consistency, develop an odor, or even become cloudy. 

There is plenty to know about using old water-based paints, and this post covers most of it. 

How Can You Tell if Water-based Paint Has Gone Bad?

If you just found an old water-based paint can, how can you tell if it has gone bad or not?

There are certain tell-tale signs that help determine if a can of paint has gone bad or not. Foul smells, repeated freezing, and thawing, or questionable consistency are all indicators of an unusable can of paint. 

Sour or Rancid-Smelling Paint

Bacterial growth may cause certain paints to have a serrated scent (foul, rancid, or vinegary) once popped open. Perhaps, some paints might have mildew or moldy smells. However, if stinky paint is used, it might evaporate but not completely. 

Repeatedly Thawed and Frozen Paints 

Your primary intention should be to keep the paint from freezing in the first place. Nonetheless, some paint manufacturers suggest that frozen paints can be effectively thawed and used.

But you need to make sure the consistency is not clumpy, and the paint is odor-free. On the other hand, paint experts caution against repetitive freezing and thawing, as the cycle will ultimately break down the paint. 

Excessively Curdled Paint

Latex paints usually develop a skin-like layer on the surface after some time. Although, if the paint has congealed completely, it’s time to discard it. In addition, it is essential to note that hardened paint bits cannot be reliquified by adding water to them. 

Jelly Consistency Paint 

Another indicator that paint has crossed its usable stage is when it is partially or entirely jelly-like. A state in which the paint is neither completely solid nor a smooth liquid but a goopy material that cannot be stirred effortlessly. 

Can You Re-Use Old Water-Based Paints?

Old water-based paints can be re-used. However, their usability depends on how they were stored. Factors such as resealing, storage conditions, and exposure to changing temperatures will determine the condition of your old paint. 

Sealed Can Of Paint

An unopened and adequately stored can of paint is pretty much guaranteed to stay in mint condition. Sealed water-based acrylic and latex paint can have a shelf life of 10 years, as they sustain their liquid to semi-liquid ratios. This helps them preserve the consistency for an extended period. Thus, when the can is opened, exposure to air begins to affect the ratio. 

Paints that have been sitting in your home for more than five years will probably have separated and will require thorough mixing. Therefore, blend the can ingredients rigorously with a paint stirrer for a minimum of five minutes. Afterward, do a little patch test to ensure the paint goes on smoothly and has the desired look. 

Related Read: Do Oil Paints Go Bad?

Opened Paint Cans

Paint cans that have been used before and resealed are not all lost causes. However, exposure to air for a long duration alters the chemical structure of the paint, therefore making the paint unusable. Thus, you need to open the can of paint and mix the contents thoroughly.

But make sure to remove the congealed layer from the top before you start stirring. Once the paint is homogenous, test its consistency on cardboard. If the paint strokes on normally, you just saved yourself a trip to the paint store. 

Paint Exposed to the Elements

If your paints have been sitting in your garage or the backyard for a couple of years now, the chances are that the paint will not be in the best condition. The reason being, paint formulas cannot withstand exposure to extreme measures of cold or heat.

You see, even unopened cans cannot survive extreme temperature abuse. All you can do is, check the consistency of the paint. Do a patch test; if your paint is grainy or lumpy in texture, it is a lost cause. 

Related Read: Will Latex Paint Expire After a While?

How Long Do Water-Based Paint Last?

Water-based paint has a shelf life of up to ten years, considering that the can is unopened and is protected against extreme temperatures. The key to extending the shelf life of an opened can of paint is keeping it tightly closed. Plus by storing it in an arid and cool place. Therefore, a well-stored but opened can of paint lasts up to two years. 

There are certain precautions you can take to ensure the longevity of your paint cans. Firstly, open the sealed lid using a proper paint can opener, and avoid using tools like screwdrivers, as they can disfigure the lid and impair the airtight sealing mechanism. Remember to keep the mouth of the can covered and pour what you need in a separate container. 

Make sure to clean the chime of the container properly with a paper towel to ensure a complete seal. Also, while storing an opened can of paint, make sure to cover the mouth of the can with plastic wrap and then fix the lid and hammer it shut. Make sure to use a rubber mallet to hammer down the lid to avoid damaging it. The tight seal will keep the paint protected from changes caused by air. 

Storing a can of paint in a temperature-controlled environment is also equally important as any of the other steps. So, preferably store the paint in a basement or a properly closed-off shed. Protecting it against elements like direct sunlight, extreme cold, or any temperature variations is vital. Lastly, place the can upside down as it helps create a liquid seal, reduces crystallization odds, and minimizes evaporation. 

Related Read: How Long Does Primer Paint Last?

How To Revive Old Water-Based Paints? 

To restore your water-based paints, add some thinning medium and stir. These thinning mediums are formulated with a little bit of water, a thinner medium, and a substance known as flow improver. The thinning medium helps salvage the dried paint without watering it down. 

Make sure to take the essential steps to protect your face, eyes, and skin before working with the thinner. Also, use a tarp to cover your work surface to avoid messy splatters and additional cleanups. 

The steps are as follows:

1. Pop The Lid

Pop The Lid

Pop open the paint container. Bear in mind dried-up paint will make it a little hard to open the lid. Using the can paint opener by prying the lid upwards little by little from all directions should certainly help. 

2. Pour In The Thinning Medium

Pour In The Thinning Medium

The thinning medium is what you need to restore your paint’s texture consistency. However, it is advised that you take suggestions from a paint store shopkeeper for the results for your brand of paint.

Also, be mindful not to add the whole thinning medium all at once. Keep checking the consistency before adding more to achieve the desired thinness of the paint. 

3. Mix The Water-Based Paint

Mix The Water-Based Paint

Proper mixing of the medium is essential to living your paint completely. Therefore, you must continue stirring in the thinning medium into the paint for a minimum of fifteen minutes.

The task may seem tedious, but it is necessary because the longer you stir, the easier it gets and smoother the consistency. Once you have acquired the perfect flowy texture of the paint, it is ready for use. 

Another and easier solution is to use a proper paint mixer. Using a paint mixer will give you a much better paint consistency and save you from the fifteen-minute stirring session.

A paint mixer is a drill-like tool that can be dipped into the paint and mix the contents thoroughly. Additionally, the paint mixer has speed options as well, and stirring the paint at high speed will give you a smoother consistency. 

Related Read: Can You Re-Use Acrylic Paint After a While?

4. Patch Test The Paint

Patch Test The Paint

At the end of your mixing process, be sure to test out the paint on a surface to determine if there are any tiny grains and impurities. If the paint looks good, get painting.

However, if you do see some lumps in the paint, you probably need to stir it more or even perhaps add some more of the thinning medium. 

Do Unopened Water-Based Paints Go Bad?

Yes, if an unopened can of water-based paint is not stored in the right place and is subject to unfavorable conditions then it can go bad.

Unopened cans of water-based paint have a shelf life of up to 10 years. Because unopened paint has not been exposed to air yet, it is able to maintain its liquids to semi-liquids ratio. However, the ingredients will have probably separated with time, but stirring the paint will fix that problem. 

On the other hand, what does damage an unopened container of paint is the extreme temperature environment. If you store your paint cans where they will get direct sunlight or extreme cold then even a sealed container might go bad. 

Related Read: Can You Use Old Polyurethane Paint?

Final Words

In the end, all you need to know is that all old paints are not a lost cause. However, it is vital to store the opened and unopened paint containers in the right place for their longevity.

Also, if you properly seal a used can of paint, it can last you up to 2 – 3 years. And it is equally essential to protect your paints from temperature fluctuations. 

Never forget to test out the paint on cardboard before you begin your DIY project. 

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