Your kitchen walls are in need of a freshening up, the bathroom could do with a lick of paint or you’re simply feeling inspired by a new DIY decor idea and instead of taking another trip to the hardware store you decide to dig out that leftover paint from a few years back. But here’s the question: ‘does paint go off?’
Most latex and acrylic paints will last perfectly fine for upwards of a decade and oil paints for up to fifteen years when stored correctly. However, paint can ‘go off’ prematurely if not stored properly. Paint that has ‘gone off’ will apply poorly and may even stink out your home so it’s wise to make sure that old paint is still good before enthusiastically covering your walls with it.
A common cause of prematurely ‘spoilt’ paint is bacteria. The bacteria can get into the paint at any stage from the factory floor to the hardware store when tinting or when you fail to fully reseal a partially used can of paint at home. Once bacteria has entered the paint it can multiply and produce a stink, which is a pretty clear indicator, when you prise open the lid, that your paint has gone off.
Low or zero VOC paints are good for the environment and living organisms as they contain less or no solvents or volatile organic compounds. These paints make a great eco-friendly choice, but what makes them friendly to living organisms also makes them more vulnerable to bacterial growth. So it’s a good idea to only purchase what you need and use up these paints as soon as possible once opened.
In any case, paint can ‘go off’ in a number of different ways and for different reasons and the shelf life of your paint depends on where you’re storing it, whether it has been opened and resealed or indeed the type of paint it is, oil-based, acrylic or water-based.
How Long Does Sealed Paint Last?
There are no hard and fast rules when it comes to the shelf life of your paint because a range of factors can come into play. However, as a general guide, previously unopened latex and acrylic paint can remain in good condition in the tin for up to 10 years, while oil and alkyd based paints can last anything up to 15 years in a sealed airtight container.
Even opened and resealed oil-based paints can usually be used for up to a decade after first opening as long as it has been stored appropriately. Oil paints are more hostile environments to bacterial and mould growth which gives them that longer shelf life.
If you’ve been storing your latex or acrylic paints in a shed or outbuilding where they have been subjected to freezing conditions this may affect the usability of the paint. Paint that freezes and thaws repeatedly will become lumpy and you could end up with an unintended pebbledash effect. To increase the shelf life of your paint store in a dark and dry space where it won’t be exposed to severe changes in temperature or moisture level
How Long Does Opened Paint Last?
For previously opened cans of paint you should expect a considerably shorter shelf life than for unopened cans. At best, when sealed and stored correctly, it is recommended to use up leftover paint within two years.
Leftover paint older than this can still be fine but it is always a good idea to check to see if paint is still in good condition before applying.
Once a paint can has been opened and exposed to the air the consistency of the paint begins to change and over time if not properly resealed will dry out entirely. When replacing the lid onto the paint ensure to tamp it down firmly with a mallet or the handle of a screwdriver.
Some people swear by storing the resealed can upside down to create an airtight seal, just be sure it is sealed tightly enough to prevent leaks if doing this.
How Long Does Paint Last In A Bucket?
If you need to leave your painting project to one side for a period of time you can leave the paint that you have poured into the bucket where it is by simply sealing the bucket with some plastic.
This can be achieved by covering with a plastic bag or sheet of plastic and sealing with a little masking tape. Once the bucket is made airtight it can be left for several days and the paint won’t dry out and form a skin on top as it would when left uncovered.
What Happens If You Use Old Paint?
You could run into a number of problems if you decide to forge ahead and use ‘suspect’ paint that may have gone off.
This is the most common problem you will encounter as old paint that has passed its prime will produce a rough finish and may even begin to crack or peel as it dries.
Old paint can produce nasty fumes. When exposed to them you could begin to feel ill or it could irritate your eyes and throat.
Alternatively, if bacteria has taken a hold of the paint the sour smell can emanate from the newly painted walls, lingering for weeks and stinking out your home.
How To Tell If Paint Has Gone Bad
If your resealed left-over paint is over two years old, or you are not sure of the age of the un-opened cans of paint in your garage, it is always wise to test the paint before embarking on a painting project with it. Here are some of the signs that your paint is no good.
- Smell – Paint has a sharp rancid, foul, or sour smell
- Mould or Mildew – If contaminated mould can be visible on the top or the paint will smell mouldy.
- Chunky – Paint that looks chunky even once you have stirred it to recombine settled ingredients. Chunks of paint can form when the paint has been frozen and thawed.
- Dried out – If the paint has dried out completely it is clearly unusable.
Does Fence Paint Go Out of Date?
The shelf life of fence paint is at least three years once stored in an airtight container. Read the manufacturer’s recommendations and instructions for use.
Can You Use Old Paint That Has Separated?
Paint that has been stored for some time will naturally separate and this is not a cause for concern. The thinner liquid will rise to the top while denser pigments will sink. Just stir and mix the paint thoroughly to recombine.
If the sediment at the bottom refuses to blend you may need to discard the paint but a thin layer of material or skin on the top is nothing to worry about, just remove and discard before mixing the paint.
In conclusion, paint may have a longer shelf life than you might expect but this is significantly reduced once the paint can has been opened. Remember to always test old paint before use and if you discover that old leftover paint has been rendered unusable over the years please dispose of it safely and responsibly.