All homeowners have the same decorating problem – paint storage. Once you’re finished painting, there’s always some leftover paint.
If you’re wise, you’ll store it because you’re going to need it for touch-ups. Especially, if it’s a water-based/latex paint as those aren’t as durable as your solvent-based paints.
The Types of Paints for Interior Decor
There’s a magnitude of paint finishes/sheens, but there’s only two types of paint. That’s all you need to be concerned about for the safe storage of it, and getting the maximum life-span.
Interior paint can be either latex/water-based or a solvent-based/alkyd paint.
The type you use will depend on the area of your home you’re painting. Solvent based paints are more durable so they last longer. They’re better suited to kitchens and bathrooms as well as kid’s rooms.
If you’re not one for constantly repainting and want a finish that’ll last beyond a couple of years, or in a kid’s room where it’s likely to be put through its paces with posters being stuck up on the walls, maybe toddlers taking crayon to the walls… then solvent-based paints will last longer, requiring fewer touch-ups.
Water-based paints are less durable and dry faster too. These are less suited to high traffic areas, but will get the job done. You’ll just need to apply fresh paint more frequently.
If you have paint leftover, and aren’t sure if you can use it to apply over existing paint…take a cotton ball, dip it in rubbing alcohol and dab it onto a test area that won’t be too visible if it lifts the paint off. Rubbing alcohol will remove water-based paint.
If it doesn’t lift the paint off, it’s solvent-based and will need a primer before a latex paint will take to it. Your paint job’s going to be easier if the paint comes off because then you can just use any water-based paint of the same shade for touch ups.
If you have a solvent-based paint and only have latex paint on hand, it can be used provided you sand it back, apply a coat of primer, let it dry then apply two to three top coats.
The easier option would be to use an alkyd paint for a fresh coat, rather than stripping the paint back, sanding, priming and switching the paint type.
Which is the Safest Paint to Use and Store in the Home?
For cleaner air around your home, water-based paints are the way to go, because solvent-based paints have a higher amount of volatile organic compounds (VOCs). Those release gases into the air, and with too much exposure, you can put you and your family’s health at risk.
The Environmental Protection Agency lists a range of health effects from high levels of VOCs, noting that “levels can be 1,000 times higher” when stripping paint.
Here’s a kicker though…
Green Seal is the standard for low to no VOC paints, making them greener, but that only applies to the manufacturing process. The two types of Green Seal paint recommended for environmentally friendly paints are GS 11 and GS 43, the latter being recycled latex paint.
The limits of VOCs in the paints are applicable to the manufacturing process, but they tell you nothing about the levels evaporating into your indoor air during the off-gassing stage – when the paint is drying.
The VOC emissions are higher than the VOCs put into the paint, so the Green Seal doesn’t make it any safer in terms of what’s in it because levels rise as the paint dries.
That’s why you need to ventilate rooms when painting, asides from the horrid odor that nobody likes.
Green Seal paints are recommended as an environmentally friendly paint, but do not let the safe seal of approval lower your guard against the dangers of VOC emissions. VOC content and VOC emission levels are very different beasts!
On to the storage of paint…
The Biggest Problem with Paint Storage is How the Can is Opened!
Paint cans should be kept airtight. That’s tricky to do if the lid of the can takes a beating when you open it, then pour directly from the can with nothing done to stop the tins guttering overflowing with paint.
One care tip to take that prevents damage from happening when you open the can is to use a paint can opener, instead of taking a screwdriver to it to pry it open. That can leave a slight dent, which is enough to let air seep into the paint can after it’s sealed.
There’s a couple of things you can do to prevent filling the gutter of the can, which later prevents you from getting an airtight seal.
1 – Punch a nail through the gutter
If you’re going to pour paint into a tray, this is the approach to take. Use a thick enough nail for the type of paint you’re using to pour through the hole.
There are paint pourers you can use, but you’ll still find some paint leakage getting into the lips of the can. Mainly from the pourer when you remove it to put the lid back on.
If you use the nail approach together with a paint pourer, put the spout over the hole so the majority of your dripped paint funnels back into the can.
2 – Use strong tape to wipe your brushes
If you’re going to be dipping your paint brush into the can instead of using a paint tray, don’t wipe the brush on the edge of the can. That’s only going to put the paint into the lip of the can, later harden and make it hard to reseal. Even harder to re-open after it’s been in storage.
Instead, put duct tape across one side of the mouth of the can. Use the edge of the tape to wipe excess paint from your brush instead of the edge of the can. If your tape isn’t thick enough, use a decent size of cardboard and stick that over the can for wiping your paint brush before using it.
Using either methods will keep the lip of the container clear, letting you get the lid back on and off easily. Even if you punch a nail through the gutter, you’ll still get an airtight seal when you put the lid back on.
When you are finished with the paint can, take the duct tape off, or remove the nail first. When you’re putting the lid back on, use a rubber mallet to tap it into place. Don’t be heavy-handed with it because if you use a hammer, you risk damaging the lid.
Any bashes, the shape gets mangled, letting air get into the can, causing the paint to lose its shelf-life. If you must use a hammer, use it with a block of wood so you’re hitting the wood with the hammer. That’ll prevent distorting the lid’s shape.
One thing to do before you put the lid on the paint can is to wipe around the lips of the tin first. Then, put some plastic wrap across the top of the tin before you put the lid on, so you can get the airtight seal.
Why Paint Needs to be Stored in An Airtight Container
There are three main components in paint. A binding agent, pigments, and solvents. The rest are additives and vary by brand. The resin that’s in paint is what causes a skin to cover the top of paint that’s been resealed. Even airtight.
That film is impossible to remove in one piece. It’ll fall to bits and if you’re not careful, you can wind up mixing it through your good paint that’s under the film surface, ruining the good parts of the paint.
If you do have paint that’s formed a thick skin across the top surface, pour it through a paint strainer to prevent the film mixing into your paint.
One thing you can try when resealing a paint can is to apply a thin layer of paint thinner (of the right type) over the top of the paint – do not mix it into the paint. Only cover thinly.
That can prevent the skin from forming and since you’re going to need to thin the paint before you re-use it, you might as well have some thinner already there to mix through.
Do not fall for the common myth of storing a paint can upside down to stop that film forming. That won’t happen. What will happen instead is the film will form at the base of the can, leaving you with no way to remove it, instead, blindly stirring it through the paint as you mix it.
The thinking behind storing paint upside down is it lets you know if you have the airtight seal, because if you don’t, the paint will leak. Seal it with plastic wrap and tap the lid down with a rubber mallet and there’s no reason to test it by storing it upside down.
Another reason to use a layer of plastic wrap is to prevent rust.
How many times have you opened an old can of paint only to find the lid’s rusted, got into the paint and ruined it?
Paint cans are manufactured poorly. Even some plastic paint tubs still have the same metal lids or at least the metal rims on them. Probably so the paint will go bad and you’ll need to buy more – of that same-brand, same tone, same finish type of paint.
Metal to metal with liquids in the lip of tin cans is a recipe for rust so if you’ve trying to figure out how to keep paint cans from rusting, plastic wrap is the answer. That’s also how to keep the paint from drying in the can because it’s an extra barrier preventing air from seeping into the tin.
The Hidden Contaminants that Will Cause Your Paint to Go Bad
If you’re painting direct from the tin, you could be taking dirt from your walls, wood or whatever you’re painting and putting it through your paint each time you dip the brush.
To get the longest life-span from your paint, pay attention to how you treat the can and the paint when you’re working with it. The best way to maximize the life-span of paint is to use a clip on pourer and pour it into a paint tray.
How Long Can Paint be Stored For?
This depends on the type of paint. Not the brand because as mentioned, there’s only two types you’ll be using. Plenty of sheens but only two types of paint. Water-based paint and oil-based paints.
Water-based paints are your acrylics and latex paint, and are much less durable than solvent based paints. In terms of the shelf-life, you can expect up to three years, but best used within two years provided it’s stored correctly. Unopened cans, where no air has reached the paint will last for longer than ten years.
Once air reaches the paint, you can typically expect it to last two to three years, although it has been known for some quality paints to last over ten years, given the storage conditions were spot-on.
Did you know that you can store paint safely without its original tin?
How to Store Paint Without a Can
Let’s suppose your paint can is trashed because the lid’s been bashed senseless after opening and closing several times. Check the type of paint you have is water-based. If it’s an oil-based paint, it means there’s petroleum distillate in it, which is some form of crude oil that’s highly flammable.
You can store it in a plastic container (at your own risk), but given it’s extremely flammable, it’s safer not to, unless you intend to store the paint inside a flammable liquids storage cabinet, giving you the peace of mind that curious young ones won’t get into it as it’s locked. These are expensive though.
Alternative Safe Paint Storage Methods for Family Homes with Kids
Where there’s curious little ones around, family safety comes first. If you have a cupboard, that’s ideal. It’s dark, it’s indoors where the temperatures will be stable, and you can put a cabinet lock on the door to prevent kids from potentially knocking the paint over, lids popping off and next thing, it’s on their skin.
If you don’t have cupboard space, the alternative is to store the paint at a height kids can’t reach, even if they climb up onto a sideboard. For cupboard storage indoors, install a shelf that will support the weight of the paint. Or, put it in the attic.
For storing water-based paints…
The Type of Plastic You Use Matters!
Plastic containers for paint should be either PET (Polyethylene Terephthalate) or HDPE (High-Density Polyethylene). Otherwise, it’ll be a permeable plastic meaning that gases from the paint can still escape, leading to off-gassing, causing the paint to dry. Like it did with this primer stored in a permeable plastic container.
The less air there is in the container, the better because that can prevent a skin from forming on top of used paint.
If the paint can lid won’t close, check the type of paint. If it’s water-based, and it’s still good to use, you can transfer it to an airtight plastic container. If it’s solvent based, chances are, it’s useless unless you have a spare empty tin can you can use with an airtight seal on it.
Plastic containers are not advised for solvent based paints stored in the home because there’s more flammable material in them. Not that water-based paints aren’t flammable. They are! I
t’s just when you’re working with them, there aren’t as many flammable materials being released into the confined space where you’re applying the paint. That’s what those nasty odors are. The fumes from the paint.
The Right Temperature to Store Paint at in the Home
Paint lasts the longest when kept at relatively stable temperatures between 60oF and 80oF (roughly 160C to 26oC).
In terms of where to store paint, it should be indoors, such as an internal cupboard, basement or attic. Not your garage floor or garden shed. Especially if you have either extreme winters or summers where temperatures fluctuate dramatically.
In terms of the relative humidity of the room, it shouldn’t be too humid and if the paint’s in a metal tin, keep it off of concrete floors as the humidity can cause condensation to form, leading to the paint can rusting.
Definitely keep all paint containers out of direct sunlight. In particular tin cans as those will heat up causing damage to the paint.
How to Store Paint in the Winter
If you’re worried about how the weather will affect the longevity of your paint, just remember it’s water based, so the freezing point is 320F. If the paint does freeze, chances are, it’s ruined.
Once it’s thawed, you’ll likely find it’s a different shade due to the higher moisture content, the texture will be different and you’ll have lumps through it.
To find out if a thawed tin of paint is usable, let it fully thaw out and brush some paint onto cardboard. If it’s lumpy or stringy, you could try continuously mixing it using a drill and a mixing attachment to get rid of the lumps, but there’s a good chance, it’ll be for nothing due to the texture and pigment change.
Safe Disposal of Paint
Depending on where you live, your local waste collection may pick up completely empty paint tins, provided you leave the lid off it so the workers can see the can is empty. If the lid’s on it, they’re likely to leave it as it could have half the contents still there, making it hazardous waste. They won’t take away paint that hasn’t been hardened.
To harden paint that’s gone bad, you can mix clay cat litter into it (with care), or use a paint thickening agent from your local hardware store.
Caution: Solidifying paint is a hazardous process and should only be done as a last resort. You can read what’s involved here and the safety precautions you need to take. Definitely DO NOT do this when kids and pets are around because it involves mixing chemicals. All sorts of hazardous!
A much safer way to dispose of unused paint is to visit the website: https://www.paintcare.org/stewardship/.
Search your area and it’ll show you where your nearest collection points are. PaintCare are a non-profit organization working alongside the Product Stewardship Council. The service only applies where U.S EPR laws are in place. Extended Producer Responsibility is an environmental initiative; not a legal requirement in all states.
There are some paint manufacturers that have voluntary programs in place with retailers that let you take back unused paint to the store. To find out, check your local paint retailer’s website, or call them up and ask if they take back unused paint.
If they do, find out how much. Some have limits so if you’re doing a garage clear-out, you could be out of luck.
For those living in non-Paint Care States, and where there’s no EPR initiatives happening, you could use the old-school method to get products used instead of tossed in the trash by just asking who needs it.
Ask a charity, ask your local painters and decorators or if you’re on social media, put up a public post up stating your area (not your address), the amount and shade of paint you have, available for free – for pick-up or if you’re generous – offer a local drop off.
A Practical Way to Safely Store Paint at Home Safely
Touch up cups are available as single cups or in pack sizes up to a dozen containers. They store small amounts (about half a pint per cup) of paint in suitable plastic airtight containers that are ideal for touch up paint jobs anytime you need to, without having to worry about air contamination, rust, or contaminants ruining the good paint leftover.
The only thing they’re missing is a pack of marbles. Without those, you’re not going to get as good a mix by shaking the cups. Pop a few marbles into your paint cups and they’ll mix it thoroughly when you shake it.
Each cup holds up to a half pint of paint and there are labels with space to write on them the color, the date and the room you used the paint in.
No matter what type of container you use, take the idea from the labels on those cups and do the same with any paint container you’re storing leftover paint in.
Organizing your paints so you know what goes where, when it was last used and the color and shade of paint will save you from opening and closing multiple paint cans until you find the one you’re looking for.