The idea of using old paint is not only a way to save money but also a way to help the environment. But can you use paint past its expiry date? And how will you know if it’s still good to use?
A tin of already opened paint should be usable if it does not contain traces of mold, rust, or lumps caused by fluctuations in temperature. If the paint tin is unopened, then it’s likely to be usable so long as the tin is airtight and has been properly stored.
The last thing you want is for your old paint to peel and crack after it’s been applied. This article is going to show you what to look out for so you can be sure of a long-lasting finish.
How Do I Know if My Paint Is Still Usable?
Paints can last for many years in the correct conditions, whether opened or not. But an opened can of paint is more likely to be off than a sealed pot. Here are some considerations when you want to use paints that have been sitting around for many years.
The liquid film on the surface is the separation of adhesive, latex, acrylics, and pigment, but you should be able to remix these components. When you reopen a can of paint and see a solid film on top, it shows that most of the useful adhesive is already gone. When you open paint, you expose it to air and set the process of curing on the way.
The lifespan of opened paint varies on how you reseal it. It may last a year or up to 5 years if you managed to get a good seal on the lid, but you can slow the hardening down by resealing the tin or sealing it in another container.
- Mold – Paint that does not contain fungicides are prone to developing mold, even more so after adding water. The signs of mold on the paint are obvious. The smell is powerful, like blue cheese, and there will be lumps in the paint. Mold may also be covering the surface of the paint with live spores, so be careful and stand back when opening the tin.
- Rust – Paints that come in metal cans often fall victim to rust contamination. Dents in the tin or scratches from mixing the paint in the can will remove the protective coating on the steel. The lid will rust first from the damage you made after removing it with whatever tool you used.
- Lumps – Overheating will damage the chemical structure of the paint, which will then form lumps. Cold weather damage can cause lumps to form in the paint and cause mold to propagate. Depending on the purpose, you mind find that you can remix the paint, and it is good enough for temporary patch-ups.
As with many sealed products, unopened paint can last far longer than the manufacturer’s expiry date. Water-based acrylic paint can still be good a decade after production, and oil-based paints for 15 years or longer.
If you have a pot of paint older than 5 years, you should mix it and then try it on scrap material to see if it sticks without peeling. With old paint, you may see that the paint on the test scrap has little clumps or flakes on the surface. This is a sign that it is past its best.
Paint cans are not always airtight. When the binders in the paint mix are isolated from the oxygen in the air, they have no catalyst to cause them to harden. Old paint metal containers can rust and contaminate the paint if the metal is dented.
Rust can work its way from the outside of the steel to the inside and discolor the paint. It is less common for mold to make it into an unopened can of paint – unless there is a bad seal around the lid.
Note: If you see signs of mold, dispose of the paint while wearing a respirator, gloves, and eye protection.
What Happens if I Use Old Paint?
Old paint is often fine to use, but if it has gone bad, you may regret using it. On outside walls, old paint may lack the strength to fight off the weather and mold. And on both interior and exterior walls, old paint may start to peel and crack as it dries.
Applications for Old Paint
If your old paint is on the turn, you may want to repurpose it on some of the following rather than dispose of it:
- Primer – Even if the paint is not the color you want to use, you can use your old paint as a base layer for new paint. This will save you money on having to use your more expensive paint on painting several layers.
- Pop Color – Use your old paint to add some pop textures to your home. Paints of different colors can brighten up doors and door frames. Or you can use several different colors to energize a bookcase or garden fence. Paint out-of-date furniture, lamps, or garden furniture.
- Canvas – Use your old paint to create artwork.
- Chalkboard – Old matt paint can be a good base for a chalkboard. Paint the back of the glass plate on a picture frame and create a handy place for making reminders and notes.
Preparing Old Paint
When you have done all your painting, you will want to seal the rest of the paint in the container so you can use it another day. Here is a list of 6 things that will help your paint last longer after opening and be in a better condition when you reopen it.
- Sieve the paint into a sealable plastic container to remove lumps, leaves, or stones that have fallen in.
- Add a tablespoon of mineral spirit to oil-based paint or water to water-based paint.
- Cover the container with plastic cling wrap and tape it into place.
- Use a rubber mallet to reseal the plastic lid onto the container.
- Store the paint in a dry place, out of direct sunlight.
- Make sure that the paint is somewhere that it will not freeze or get too hot.
How to Dispose of Old Paint
Signs that your paint is beyond a salvageable state include films of mold, coatings of rust, and lumps on the surface of the paint. Even with sieving, the paint can discolor from rust or mold contamination and lose its ability to adhere. If the paint has reached this point, just admit that it is time to throw it away.
Environmental laws forbid the dumping of paint into sewage systems or pouring it into the ground – but you can put hardened water-based paint in the garbage. Paint hardener turns latex and acrylic paint hard within 20 minutes so that you can dispose of it without making a mess.
You can also harden the paint by mixing what you have into cat litter. Oil-based paints should be taken to a recycling center for safe and controlled disposal.