So you are almost ready to start your next DIY painting project, but your aerosol paint won’t spray anymore? You are sure there’s much paint in it, but the sprayer won’t blow.
Yup. It has lost pressure.
For many years, aerosol cans housed and dispersed different types of products, including paint. From insecticides to home cleaning to automotive products, these cans served humans their purpose enough to exist and still become usable up to date.
But for a container that relies on pressure to disperse its product, the loss of this force could mean not being able to consume the product up to its last bits. Some people risk reapplying pressure on the aerosol can. But is that enough to maximize the use of the remaining paint? Can you still use the paint?
To answer your question, we explain the science behind aerosol cans and what to do with the remaining paint.
The Role of Pressure in an Aerosol Can
When we speak of aerosol, it is the fine mist of liquid and gas from the can sprayer. The aerosol can is a tool used to spray liquid from the can into fine mists. It uses a pressurized liquid called propellant to force the paint out of the sprayer. Propellant comes in a mixture of butane, propane, or isobutane. Manufacturers fill them tightly into the can so the mist comes out evenly.
To understand the role of air pressure in aerosol cans, check this out:
There are two main content inside an aerosol can: the propellant and the product. The propellant helps in pushing the content through the sprayer.
The pressure helps the contents break down into small particles to apply them in an equal and more controllable motion.
Spray pattern control
The pressure works with the valve pattern to provide a controlled dispersal and direction of the atomized liquid particles.
The pressure inside keeps the product away from contaminants and impurities from entering the canister, maintaining the quality of the aerosol.
How Does A Can of Aerosol Lose Pressure?
A can of aerosol loses pressure because of different circumstances:
Leakage or damaged seals
Degradation of propellant
Over time, even a stored aerosol can lose its pressure due to propellant degradation. Propellant degradation is a result of temperature fluctuations, exposure to sunlight, or chemicals that lead to propellant weakening inside the can.
Also, the product needs a correct ratio of propellant and paint. Whether the propellant is less or more than the required ratio, it may cause the canister to lose pressure.
Another reason aerosol can lose pressure is by using it for an extended period. This act can deplete the propellant.
Signs that the Aerosol Can is Losing or has Lost Pressure
If you are here because you think your aerosol paint must have lost pressure, recall if one of these signs happened before:
Not spraying or weakened dispersal
Uneven spray output
Difficulty in spraying
A noticeable slow dispensing of paint mist
Audible hissing or leaking sound
Puncture or dent
What Happens to the Paint When the Aerosol Can Lose Pressure?
When the aerosol can has lost pressure, the canister does not have pressure to block impurities and contaminants. If the lost pressure is due to extreme temperature or chemical exposure, it may affect the quality of the paint. If you are willing to transfer the contents into another container, you may still use the remaining content.
However, remember that the paint quality relies on the amount of propellant in the aerosol can. The spray paint product is formulated for misting. So whether you use it through another application, expect it to have a different paint quality than when sprayed correctly.
Increased drying time
Paint may dry inside
.Paint may become contaminated
Paint may not atomize when left depressurized for a long time
Reduced paint coverage
Trouble achieving fine detailing
Changes in viscosity
Signs that You Can Still Use the Paint When Aerosol Can Lost Pressure
Some cases may affect the quality, but the paint is still usable.
If the paint has not dried after visual inspection, clumped, or made any lumps, you may still use the remaining content. If it has no signs of contamination or impurities, check for consistency. When there is no change in texture, the paint did not degrade.
If there’s any significant change in odor, the paint may not be worth salvaging.
If the aerosol can lose pressure during proper storage, the paint quality may still be good for reuse. Proper storage means placing the aerosol away from extreme temperatures or sunlight exposure.
You can still use the content with proper storage because the propellant and the paint do not mix inside. They come in separate layers. That’s why you need to shake the can before using it. So the probability of the paint maintaining its quality is high with proper storage.
When assessing the quality of remaining paint in aerosol cans, consider its previous usage, the storage duration, the storage conditions, the cause of your aerosol paint lost pressure, and the aerosol can condition.
Can you Refill the Pressure on Aerosol Cans Instead?
While you can do this technically, trying it is not worth the effort. Many people do this for the first time and end up with a whole mess. Remember that depressurized aerosol may still contain pressure inside. And it is unsafe to handle them unless you are professional.
People used air compressors and tire chuck to reapply pressure inside aerosol cans. But the aerosol paint in a can will need the ratio of the propellant and remaining paint. While you can get this information from the manufacturer, you must know how much paint remains in the can.
Also, you have no idea how much force the aerosol can take. Not all aerosol cans are suitable for refilling.
Those who use the tire chuck-air compressor combo will fill the can with air. The air, with oxygen and water vapor, is enough to contaminate the remaining paint.
What are the challenges of refilling aerosol cans?
A balanced propellant and the correct ratio
Manufacturers optimize the paint content for aerosol spraying. The product requires a balanced propellant and paint ratio for optimal misting of spray paint.
The amount of air force for filling is integral in restoring the functionality of the aerosol can. This amount is enough to maintain consistent performance for proper spray patterns and coverage for better control.
The possible danger in handling
The refilling job can cause injury, safety hazards, and chemical exposures. Also, the remaining pressure can cause fire hazards as most propellants left in the can are mostly flammable. If you have no experience handling air-filled cans, you may end up in a mess or injuries.
You need a refillable can for this purpose.
Most aerosol cans are designed for single-use applications and are not for refilling. For this reason, it can handle one-time filling of pressure. These cans may not withstand the refilling process and may cause a structural failure like leaking or explosion.
Alternative Ways to Use the Remaining Paint in a Depressurized Aerosol Can
If you want to use the remaining paint in an aerosol can that lost its pressure, the best thing you can do is puncture the can and transfer its remaining content. You will need a clean container, a puncturing tool or can opener, safety goggles & gloves, and old working clothes. Expect that the job will be messy.
Prepare your workstation. Release the remaining pressure inside. Puncture the can and ensure to direct it away for you or anything the splattered paint may damage. Open the entire can and use a spatula or similar to transfer it. Scrape as you can and seal the new container in a jar.
1) Paintbrush or roller
If the paint kept its consistency, remember that your manufacturer formulated it for fine misting. So expect that the quality is unlike the paint for manual application.
2) Spray Gun
Still, it does not guarantee that you get the quality of finely misted aerosol paint with a spray gun. The paint is optimized for a balance propellent–paint ratio. Also, there will be differences in the coverage. Still, this method is doable.
Technically, you can still use the remaining paint from aerosol cans that lost their pressure. If you choose this path, remember the safety precautions in handling aerosol cans. But even if you successfully transfer the paint into a separate container, the paint quality may diminish since you need the air force to mist it in fine drops.
And even if you successfully refilled it with air pressure, it does not guarantee can atomize the paint and maintain its paint quality. Remember that the aerosol paint in the can you bought is disposable and for single use.
If you use the remaining paint using alternative methods, test it on one surface first. And although you can successfully apply it on the surface, it doesn’t guarantee the paint will adhere enough as much as it does on its aerosol can.
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