Many have leftover paint after finishing a job so the next question is how long does paint last. Fortunately, unopened paint is usable for 10 – 15 years and opened paint cans often remain good for several years, as well.
However, don’t use the paint blindly – always check the quality first. Certain paints might thicken and it can clog your paint sprayer, it depends on the type of paint sprayer if it is then still suitable.
You don’t want old paint to leave marks on newly prepared walls so read on to find out how to check the quality of paint and how to rescue old stored paint.
How Long Does Paint Last Unopened and How to Store It
An unopened paint can last several years. The exact time depends on the particular kind of paint and how the can has been stored.
Oil-based paints and other solvent-based types last the longest, up to 15 years if stored properly. Water-based paints also last very long under the right conditions, approximately 10 years.
Paint is somewhat sensitive to temperature so make sure the storage place is dry and does not get too warm nor too cold. Store unopened cans in a room where it does not freeze and away from direct sunlight.
In this case, taking care of the canister is just as important. Make sure it does not get damaged in any way and that the seal stays shut tight.
If you have an unopened can but it seems damaged, for example, a bulge, then it is likely that it is no longer usable. Read on to find out how to check whether the paint is still good.
How to Store Opened Paint
With proper storage, you can still use paint for several years after the can has been opened. Like with an opened can, the temperature is one of the important factors.
Temperature changes affect the consistency of paint – the different components might separate or congeal. This is why opened cans should also be kept in a dry and cool place that neither gets too hot or too cold.
The other important element in storing paint is air. An airtight seal is key because this prevents deterioration of the quality.
Make sure the top of the can is clean and the lid fits in tightly. However, don’t force the lid shut to the point of damaging it because if it is dented or misshapen the seal is no longer effective.
If you only have a small amount of paint left, it is smarter to transfer the remainder into a smaller container with an airtight seal like a glass jar. This minimizes the amount of air inside the container.
How to Test If Paint Is Still Good
Finding out whether the paint is still usable is relatively easy. There are a few key signs of expired paint that are simple enough to spot.
Paint that has been stored for a while might have taken on an unusual consistency so don’t think it is bad right away. Stir the paint for about 5 minutes until it gets to the right consistency.
Then, take a little dab, brush it onto a cardboard tester and let it dry completely. If it has a smooth finish then the paint is still usable.
However, if the final result is grainy, the paint is no longer usable. Don’t use this paint because you won’t get good results.
1. Film at the Top
It is quite normal for opened paint cans to develop a thick film at the top. However, if the rest of the paint is still smooth, you can simply remove the filmy layer and use the rest.
2. Bad Smell
Although it never smells particularly pleasant, bad paint has a more rancid smell. Horrible smelling paint means it contains bacteria and must be disposed of safely according to your state regulations.
Lumps are a result of temperature changes. Sometimes, you can filter them out when it is just a few lumps but in many cases, it is a sign that the paint has gone bad.
4. Rusty Container
As mentioned, the quality of the container is just as important. If the can is rusty, there is a good chance that the paint has been contaminated, as well, and so should no longer be used.
How to Dispose of Bad Paint
If you do discover that your paint has gone bad, you have to dispose of it in a safe and environmentally friendly manner. The correct method differs per type of paint so make sure you follow the correct steps for paint disposal.
The safest bet is taking the leftover paint to a recycling center. The hardware shop might also take in old paint.