Why Does Spray Paint Bubble?


Last updated: June 2, 2023

Get expert tips and advice on why your spray paint bubbles and how to avoid it.

A photo of bubbled spray paint to illustrate why does spray paint bubble

When spray painting, you’d always expect to get a smooth and attractive finish. But that’s not always the case because so many things can go wrong with spray paint jobs. One of these is spray paint bubbling. It’s not uncommon to notice these small bumps of air on a paint job, whether a few hours after a project or much later.

Bubbling is one of the most frustrating things that can go wrong with spray paint. Luckily for you, it can be fixed and prevented. In this article, we will look at what causes spray paint to bubble, how to fix it, and what you can do to prevent it in the future.

Why does spray paint bubble?

The two main causes of bubbling in spray paint are; not adequately preparing the surface and painting in extreme heat or cold. Also, if you use a coating that is too thick, it will take longer to dry, and bubbles might begin to form. Each of these conditions makes it difficult for the paint to adhere perfectly to the surface, ultimately leading to bubbles.

Why Does My Spray Paint Bubble?

Several factors can cause bubbles to emerge in spray paint. Let’s look at them closely.

Bad Weather

Bad weather can affect your paint job, so you should always do a rain check before you commence your project.

When there’s excess moisture or high humidity, the paint takes longer to dry, resulting in poor adhesion. This causes moisture to penetrate the surface before it’s fully dry, allowing bubbles to form under the paint.

Likewise, when it’s too hot outside, the topcoat can dry unevenly at a speedy rate, causing bubbles or blisters under the paint.

To prevent this, avoid painting within hours of rain or storm. Instead, choose a time when the weather is cool and dry, ideally, temperatures between 50 to 85 degrees F. One way to keep humidity in check, especially if you’re painting in an area that’s not properly ventilated, is to use a fan or dehumidifier.

Dirty Surface

A dirty surface affects the ability of your spray paint to adhere properly. This is because dirt pulls the paint away from the base, allowing air to fill the void and form bubbles. No wonder manufacturers recommend cleaning or prepping the surface before you begin your project.

This applies to all types of dirt, including grease, grime, dust, mud, and mold stains.

You can use a damp sponge soaked in soapy water to clean the surface. Sometimes you may need to pressure wash to remove excess mold, mildew, or grime buildup. This is highly recommended for exterior surfaces, especially metals.

Don’t always be in a hurry to start painting. Make sure everything is washed and cleaned first. A paint job is only as good as the surface it’s applied on.

Skipping Primer

Another thing that can cause bubbles in spray paint is skipping primer. This can happen especially when painting porous materials such as bare wood, plaster, concrete, or bare drywall.

Priming makes a porous surface less porous, so the base coat and additional coatings will stick better. In other words, if you don’t apply a primer, the base coat can get absorbed into the surface, making it difficult for subsequent coats to stick. When this happens, the new layer of paint tends to lift off from the base coat. This often results in the formation of bubbles in the top coat.

Besides providing a base for your paint, priming also helps to cover up stains. So, it’s a good practice to always clean, dry, and prime items before you paint.

Latex and oil-based primers are more common, but you can choose any type as long as it’s compatible with the spray paint. We recommend oil-based primers for outdoor surfaces and high-moisture areas because they offer more resistance to water or moisture.

Why Does Spray Paint Bubble On Different Surfaces?

Spray paint bubbles affect different surfaces, but the underlying causes are the same – dirt, grime, molting from old paint, moisture, and extreme heat. All these boil down to a lack of preparation. Most people just want to start spray painting without washing or cleaning the surface; unfortunately, that doesn’t always work out.

Another reason bubbling occurs on different surfaces is painting when it’s too cold or hot outside. Paint takes longer to dry when there’s a lot of moisture in the air (high humidity). In this case, if you start applying a second coat before the base coat has enough time to dry fully, it will cause bubbles.

Likewise, extreme cold can cause bubbling on different materials, but the effect is usually more in metals. This is because metals are more prone to extremely cold temperatures and will stay colder for longer periods than other materials, such as wicker or wood. This prevents the paint from adhering perfectly to the surface. For this reason, it’s best to paint metals on warmer days.

In addition to temperature changes, using the wrong number of coats or using heavy coats of paint can lead to bubbling. It’s best to apply many light layers. It might mean more work, but you will be pleased with the outcome.

Why Does Spray Paint Bubble On Metal?

Applying spray paint on metal is supposed to leave a smooth finish with a metallic sheen. But if, after painting, you notice imperfections like bubbles or blisters, then you probably did something wrong. Before fixing the bubbles, it’s vital to know exactly what’s causing it. Below are the main causes of spray paint bubbles on metal surfaces:

  • Contaminants or dirt on the substrate ( you didn’t clean the surface)
  • Not preparing the surface well (it’s either rough or filled with cracks, or dents or other imperfections)
  • Painting metal when the weather is too hot or cold
  • Not allowing the base coat to fully dry
  • Using too much paint in the second coat 

Also, if the surface you’re painting is naturally porous or rough, air can easily get trapped underneath the coatings, leading to bubbles. One of the best ways to prevent this is to seal off the pores and air pockets with a primer before applying the first coat and subsequent ones.

Why does spray paint bubble on wood?

If you notice spray paint bubbles on your wood piece, then there are a few things that may be causing it.

First, it could be a result of too much heat or moisture in the air. High humidity levels cause the paint to dry too slowly and allow bubbles or blisters to form. Likewise, if you paint at a temperature above 85 degrees, the top layers will dry rapidly and unevenly.

Secondly, painting over wood while it’s still wet or dirty can cause bubbling. You will also have the same problem if you don’t prepare or sand the wood properly before painting, as the paint won’t adhere correctly.

Another thing that can cause spray paint bubbles on wood is when you spray a previously painted surface with another type of paint. For instance, painting an oil-based product over latex or vice versa. Oil-based paints contain volatile solvents underneath that do not mix/react well with latex paint.

Why Does Spray Paint Bubble On Plastic?

Spray paint bubbles on plastic can be caused by a variety of things. These include:

  • Not cleaning the surface before painting
  • Applying coatings that are too thick
  • Not allowing each coat to cure properly
  • The plastic surface not being smooth enough
  • Using spray paint that is not meant for plastic
  • Painting in excess heat or moisture 

Fixing spray paint bubble on plastic is pretty straightforward and usually involves removing the bubbles with a brush or sanding it down, priming the surface, and repainting. 

Why Does Spray Paint Bubble On Glass?

Bubbled spray paint occur on glass surfaces for the same reason as other materials. Painting in high temperatures or humidity is the main cause of bubbles on glass paint. Also, if you don’t prepare the surface well enough, you will likely experience the same problem.

Make sure to shake the spray paint bottle before using it. But don’t overdo it. Also, avoid applying too thick of a layer. It’s best to use several thin coats instead. Don’t apply a second coat until the base coat has fully dried.

Why is My Second Coat of Spray Paint Bubbling?

It is not uncommon to notice bubbling on spray paint after applying a second coat. So, why does spray paint bubble on a second coat?

Spray paint may bubble on the second coat if the base coat is too thick. In this case, the second coast will be uneven. The best way to avoid this is to use a thin layer of paint for the base coat and subsequent coating.

Another thing that can cause bubbling after a second coat of paint is when the base coat is not allowed to fully dry before painting on top. This is often the case when you paint in a space that is too wet or humid. The paint will take longer to dry on the first coat, and even when it dries; it might not adhere perfectly.

To avoid this problem, avoid subjecting the paint to excess moisture or direct sunlight, and make sure the base coat is clean and dry before applying a second coat.

Why is my paint bubbling the next day after spray paint?

If your paint is bubbling the next day after spray paint, it can mean a number of things, but the most common culprit is poor preparation. Painting directly on a dirty surface or one with an old painting will often lead to bubbling because the paint will not be able to bond well to the surface. This applies no matter how good your paint is. 

Other potential causes include:

  • Using low-quality spray paint.
  • Painting latex paint over oil-based paint or vice versa.
  • Painting in direct sunlight or extremely low temperatures. 

Why Do Air Bubbles Occur When Spraying Latex Paint?

Air bubbles occur in latex paint when it’s mixed or put over oil-based paint. Latex paint doesn’t bond well with oil-based paint. This means that if you apply a base coat of oil-based paint and spray latex over it, you may have bubbles.

Other things that can cause bubbling in latex paint include using a spray gun with a small fluid nozzle and cleaning the work surface properly before painting.

How Can I Prevent Air Bubbles in Spray Paint?

There’s no better way to handle air bubble in spray paint than to prevent it. And when it comes to prevention, the most important item is preparation. A paint job is only as good as the surface it was applied on. In other words, you can drastically minimize the chances of bubbles occurring by adequately preparing your workpiece.

So, before painting any surface, make sure it’s clean and dry. Use a sponge and soapy water to wipe off dust and dirt. Then rinse with clean water and wipe with a clean, dry towel. Allow the surface to dry before you proceed.

Next, you may want to prime the surface. Priming helps to cover stains and allows the paint to adhere better. Choose a primer specifically designed for the type of material you’re painting.

Also, avoid painting in high heat or humidity, as that can result in bubbling. Instead, paint in dry, cool conditions; ideally, this should be in the temperature range recommended by the paint manufacturer. Generally, we found anything between 50 to 85 degrees F to be conducive.

Try to check the local weather forecast before you decide when to paint. If you’re working in an area that is not well-ventilated, consider using a fan or dehumidifier to speed up drying and keep humidity in check.

Why Does Spray Paint Bubble?

How To Avoid Spray Paint Bubbles?

As earlier indicated, improper preparation is the major culprit of spray paint bubbles. This means that preparing the surface and selecting the right tools are essential to ensuring a successful project.

Also, shaking the spray paint can vigorously is one of the most common ways to avoid bubbles. Not shaking the paint can properly before use leaves many bubbles in the container, which are transferred to the workpiece when you press the nozzle.

Spray in side-by-side motion, and try to release the button at the end of each press. Apply multiple thin coats of paint instead of a thick layer.

Finally, allow the paint dry completely between coats and avoid painting when the weather is too hot or cold.

Can Bubbled Paint Be Fixed?

Yes, bubbled paint can be repaired, but it’s better to be proactive about preparing the surface so you won’t need to go back and make corrections later on.

In general, fixing spray paint bubble is not difficult and depends on the severity of the problem.

Sometimes, the bubbles will pop quickly on their own. In this case, you don’t need to do anything; just allow it to dry. If the bubbles appear after you apply a second coat, they will likely go away too.

However, if the bubbles seem not to go away, then you can follow the steps in the next section to get rid of them.

How To Fix Bubbles In Spray Paint?

Follow these steps to fix spray paint bubbles released onto your project.

Let the Paint Dry

First, allow the paint to dry. Sometimes, air bubbles can go away on their own without you having to do anything. But you will never know until the paint has fully cured. So, even though you notice the bubbles early in the project, wait until the paint has fully cured before taking any step to remove it.

Remove Damaged Paint

If, after drying, the bubbles don’t go away, the next thing you want to do is scrape off the affected area. You can use a scraper or putty knife for this purpose. We recommend wearing a respirator and other protective equipment to protect your lungs, as scraping and sanding can generate a lot of dust or fumes, especially if the damaged paint is oil-based.

Prepare the Surface

Next, prepare the surface. Start by filling any holes or pits in the surface with a patching compound. Allow the compound to dry, then lightly sand off all the patches or loose paint with a fine-grit sandpaper. The grit level of the sandpaper will depend on the surface. Generally, we recommend a grit of 100 or above. If you can, switch the sandpaper whenever it becomes clogged with debris and no longer removes paint as it used to.

After sanding, wipe the surface clean and allow it to dry. Then apply a new layer of primer if necessary and allow it to dry.

Apply New Paint

Once the primer coat dries, you can apply fresh paint. Hold the bottle 6 inches away from the surface and spray evenly, moving side to side.

Allow the first coat to dry completely before applying the next one. Applying another coat before the previous one has fully dried is what causes bubbles. You can check the product label to see how long you need to wait. Avoid using too much paint in a single coat; it’s better to apply multiple light coats.

Wait for the top coat to cure fully before using the piece again.

FAQS – Why Does Spray Paint Bubble?

Do Paint Bubbles Go Away?

Some paint bubbles may resolve on their own as the paint cures. This is more common if you’re painting in high heat, as this speeds up drying. In this case, it’s possible for the bubbles to go away without leaving craters or cracks. Otherwise, the bubbles will burst eventually and leave unsightly cracks in the paint job.

Is It Okay to Pop the Paint Bubbles?

No, it’s not OK to pop paint bubbles, as that could ruin your paint job. It’s better to leave it to dry. Sometimes, the bubbles will go away on their own as the paint cures; otherwise, you can scrape the area with a putty knife or remove the damaged patches.

Why is My Airless Paint Sprayer Leaving Bubbles?

If your sprayer is leaving bubbles, then there’s a good chance you’re applying too much paint. When the coating is too thick, it traps air and forms bubbles before the paint gets a chance to dry and level itself.

Why is My Spray Paint Blotchy?

Three main things cause blotching in spray paint – not handling the sprayer or spray paint can correctly, painting one spot for too long (dripping), and allowing the paint to get contaminated with water or oil from your body or other painting material. 

Summary: Why is My Spray Paint Bubbling?

To conclude, spray paint bubble occurs when you don’t properly prepare the surface you’re painting or use a coating that is too thick. Painting in extreme temperature conditions can also cause bubbling.

The main takeaway here is to always prepare your workpiece before painting to avoid bubbles. And even if you encounter the problem, you know how to fix it. Now, you’re ready to tackle your next painting project with more confidence!

Don’t allow blisters or bubbles to ruin your project. Follow the guidelines here to get the ultimate results. We hope we’ve answered your questions about why does spray paint bubble and how to fix it. Let us know if you have any more problems; we will be glad to help.

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