If you are buying paint for your next DIY home painting project it’s more than likely you will have some leftover, which is not a bad thing since it can be used for future touch-ups to cover any knicks, dents, scuff marks, scratches until you have to repaint again.
But how do you know if the paint you’ve been saving stored away in a basement, garage or shed is still good to use? Is it properly sealed and stored in the right conditions? Does paint expire? Is paint still good after a year? Is an opened can of paint still good to use?
These are common questions homeowners and DIYers may have if they have been saving paint for a future use.
If you are wondering whether the left-over paint ever expires or how long an open gallon of paint will last in storage, you’ve come to the right place to learn how to properly store it and how to safely and environmentally friendly dispose of it.
How Do You Know If Paint Is Still Good To Use
If properly sealed and stored at the right temperature paint can last a couple of years. If you have some saved up leftover paint from a previous project and need to repaint or touch-up an area here are a few signs that tell you paint is now longer good to use and you need to properly dispose of it.
Signs of Expired Paint Gone Bad
When a can of paint has been sitting in a basement or garage for more than six months and is re-opened for use you will notice a thick rubber-like film on the top of the paint. This means the paint is no longer good to use and has expired.
A bulging or lifting lid is a sign that the paint is no longer good to use. When paint sits for a long time and is not properly resealed for storage there are particles in the air, dust and other organisms that can enter through gaps in the lid and form gases that then create pressure inside the paint can causing it to bulge or pop.
If the paint emanates a strong foul smell like that of rotten eggs this is a sure tell sign the paint has gone bad and should not be re-used but rather properly and safely disposed of.
How Long Does An Unopened Can Of Paint Last
If you have ever done a DIY painting project you will know that there can always be some paint left over.
An unopened, never used can or gallon of paint can last forever but it’s the standard amongst paint manufacturing companies to give it a shelf life that is anywhere between 10 to 15 years.
An unopened can of interior latex or oil based paint can last up to two years if properly sealed and stored in a cool dry area. Keep it away from heat and cold temperatures and always avoid it freezing.
How Long Does An Unused Can Of Paint Last
If a paint can has never been opened, used or pre-mixed it can keep for over a decade when properly stored. Only after the can is opened or pre-mixed for a specific colour does the standard shelf life diminish.
How Long Does An Open Can Of Paint Last
Regardless of whether it is a water or oil based paint an open can of paint can last up to about two years when sealed tightly and properly stored in a cool dry area.
When exposed to different temperatures or air the opened cans of paint will usually separate from its solid base. Once the liquid separates from the solid mix of the paint it will never go back to it’s original state and therefore makes the opened paint gallon un-useable. It is not recommended to use open cans of paint after two years since the paint may have gone bad.
If you do have leftover paint you want to make sure your properly store it or dispose of it. Here are our tips on how to.
How Long Does A Pre-Mixed Can Of Paint Last
An already pre-mixed can of paint has a shorter life span that an unused or un-opened can of paint that does not have any colours added. If you have pre-mixed paint in storage that was used in a previous project you should open it up and check it out.
Start by shaking and stirring to remix the paint. If the paint comes together with no separation between the water or oil bases then you can most likely still make use of it.
Here is the typical shelf life on the different types of paints.
Water-based paints such as latex or acrylic can last anywhere from 2 to 10 years with proper re-seal and storage conditions.
Oil-Based Paints can last up to 15 years or more especially when stored in the right temperature environments. Do not leave outdoors to freeze as this will destroy the paint and render it completely useless. You can however thaw frozen paint and as long as when applied to the surface there are no clumps and no foul smells that come from the paint then you can re-use it. Avoid repetitive freeze and thaw cycles as paint experts advise this breaks down the structure of the paint.
How To Store and Save Leftover Paint
In doing so you will avoid having too much leftover paints as well as avoid the disappointment of not being able to return any unused paints that have been pre-mixed in specific to your project colours .
Store any leftover paints to preserve its quality and render it useable for small touch-ups by making sure it is in a tightly air sealed container or make sure the lid on the can is securely and tightly placed back onto the can.
Small amounts of leftover water-based paints can be stored in air tight containers or glass jars with tightly fitted and sealing lids. If you have a half gallon or more leftover paint we would recommend saving it in the can it comes in. Oil-based paints should be preserved in the cans they came in.
Paint should be stored at room temperature and it should be avoided from being left outside in a garage or shed especially if you live in areas where the winter temperatures are frigid like here in Ottawa, Canada where our temperatures can dip down to the -30’s Celsius or more.
Bonus Tip ** Write on the paint can or on a label the name of the colour used, the day, month, and year and which room the leftover paint was used in. By doing this it will help you remember the next time you want to or need to use it.
How To Safely And Environmentally Friendly Dispose Of Leftover Paint
If you are not going to save the leftover paint or it expired and gone bad making it useless you can’t just throw it out with the garbage or pour it down city drains.
It is actually against the law here in Ottawa to pour paint or other solvents down the drains of our city streets.
You should safely and properly dispose of any of the hazardous materials by visiting your local municipality of the City of Ottawa to see when the collection of hazardous materials is.
It is actually against the law to pour paint down the drains of our city streets. You can safely and environmentally friendly and conscientiously dispose of it by visiting your local City of Ottawa municipality for dates and locations in Ottawa to dispose of hazardous waste and special items.
This post was originally published on May 12, 2017 and edited on June 22, 2021