This post may contain affiliate links which means I may receive a commission for purchases made through links.
After repainting your car, paint bubbles or blisters may appear on the new coat, usually 2 – 3 months after application. In fact, this is one of the most common complaints leveled at all auto body shops and car paint manufacturers.
Yet it’s one of the most challenging and toughest issues to explain to the auto body shop. Why would car paint bubble in the first place?
Relax! In this article, I’ll show you everything you need to know about car paint bubbling, including its causes, prevention, and how to fix it! That way, you can easily avoid this problem next time you paint your classic car.
What is Car Paint Bubbling?
Also known as paint blistering, paint bubbling generally refers to a pocket of fluid that forms between the dried car paint. The pocket then expands to form blisters or bubbles that eventually break open, leaving marks and holes on the painted surface.
Car paint bubbles can be classified into various categories. The most common types of paint bubbles are:
This refers to uniform bubbles/ blisters that form across the bodywork panel. Tiny car paint bubbles usually occur when there is moisture on the car surface during the painting process.
For instance, painting a car when there is too much moisture in the atmosphere will cause tiny bubbles to form due to the moisture trapped under drying paint. On the downside, repairing this type of car paint bubble requires you to refinish the entire bodywork panel.
Car paint delamination
Car paint delamination is a car paint problem that occurs when the paint starts to break down over time mainly due to exposure to the sun. As a result, the clear coat breaks down, affecting its ability to protect the colored base coat.
Consequently, small bubbles start forming on the car’s surface, causing the paint to peel off over time. The only way to fix this problem is to strip off the peeling coat and refinish it.
Solvent pop bubbles
Solvent pop is a condition that occurs when you apply too much paint too fast and apply a clear coat over it. As the solvent from the car paint tries to escape, it’s trapped by the clear coat, causing tiny pinholes to appear on the surface.
Interestingly, this problem is not too severe as it can be buffed and sanded out.
Common causes of car paint bubbling
Too much moisture
Moisture can easily get trapped under the car paint if there is too much moisture in the atmosphere or paint mixture. Also, this can occur when the paint is exposed to lots of moisture while it’s still fresh.
The same case can also occur if you store your car outside in rainy, humid, and snowy conditions. This will cause the paint to deteriorate and start chipping away over time.
Contaminated painted surface
Applying car paint over moisture or solid debris is another factor that can cause the car paint to bubble. Moreover, this traps small pockets of moisture or air beneath the paint.
Eventually, these pockets contract and expand due to weather changes, causing bubbles to form on the car paint. To avoid this problem, always prepare the surface before you apply a fresh coat of paint or have a professional do the job for you.
Applying too much paint too fast
As mentioned earlier, solvent pop bubbles are formed when you apply the clear coat too fast. As a result, small bubbles that let moisture in are formed, causing bubbles known as solvent pop bubbles to form on the car’s surface.
Hot painting surface
Applying car paint on a hot surface causes it to warp as it dries. Alternatively, the paint will dry too quickly and lose its ability to adhere to the car surface, causing it to bubble or peel off over time.
Luckily, you can avoid this problem by painting your car under the shade. Also, avoid painting your car in direct sunlight or in very hot weather.
Any type of car paint will eventually age over time, even if you live in a very dry location or regularly park your car indoors. Over time, the paint becomes weaker until it starts to peel, chip, or bubble, a condition known as delamination.
Does rust cause car paint to bubble?
Rust and corrosion can also cause the car paint to experience adhesion issues and start bubbling. Besides, rust cannot happen without moisture, which is one of the major causes of car paint bubbling.
Therefore, when moisture finds its way into the metal surface underneath the car paint, it triggers a chemical reaction, causing a bubbling texture to form in the paint over time.
How to fix car paint bubbling
After identifying the cause of car paint bubbling on your car surface, the next step is to fix it. Luckily, there are various solutions you can use depending on the type of car paint bubbles on your car’s paintwork.
In this section, we’ll look at the general steps you can use to fix almost every type of car paint bubbling you encounter.
First, let’s look at some of the items you’ll need for the project:
- Clean microfiber cloths
- Wax & grease remover
- Wire wheel brush
- Masking tape
- Body filler, hardener
- Sanding block
- 80-, 180-, 320-, 400- & 600-grit sandpaper
- Spot putty
- Mixing board and spreader
- Filler primer
- Self-etching primer
- Perfectly matched car paint
- Clear coat
- Orbital buffer
- Tack cloth
- Light-cutting compound/ polish
Step 1: Clean the area with paint bubbles using a wax & grease remover
After gathering all the necessary items, thoroughly clean the affected area on your car with the best wax and grease remover you can find. This helps you to remove wax, road grime, tar, and any other contaminant that hinder the sanding process.
Step 2: Protect the surrounding areas
Use masking tape to protect the surrounding areas around the car paint bubbles you intend to repair. If the trim cannot be removed, put a Q-tip between the edge and the trim and use masking tape to cover the entire area.
Step 3: Remove the rust with a wire brush
Scrub the rusted area with a wire brush on a grinder to remove as much of the rust as possible, holding the grinder steady. Next, remove the remaining rust with the rough 80-grit sandpaper wrapped around a sanding block.
Make sure you use a cross-hatch pattern while sanding to get uniform coverage down to the metal surface.
Step 4: Apply the body filler to the sanded area
Use compressed air to get rid of the sandpaper dust on the sanded area until there are no dust particles on the surface. Then mix the body filler and hardener according to the manufacturer’s instructions and lightly spread the mixture over the sanded area with a squeegee.
Let the filler cure as indicated on the product’s specifications before sanding it with the 80-grit sandpaper using a cross-hatch pattern. Continue sanding the surface as you upgrade the sandpaper grits from rough to smooth until you get a perfectly smooth surface.
Step 5: Apply the spot putty
Use spot putty to repair minor imperfections on the car surface and let it dry. Afterward, sand the surface again with 400-grit sandpaper until you get a smooth finish.
Step 6: Apply the primer
First of all, clean the entire area with a wax & grease remover and let the surface dry. Use masking tape to cover the areas you don’t want the primer to reach and apply a coat of self-etching primer.
Once the primer dries, apply another coat of filler primer, let it dry, and light sand with 400-grit sandpaper until the surface is perfectly smooth. Finish off the surface with the finer 600-grit sandpaper before you apply the paint.
Step 7: Paint the surface
Thoroughly clean the repaired area and dry with a clean car-drying microfiber towel, then apply the 1st coat of perfectly matched car paint. Apply 2-3 coats of the paint, allowing each layer to dry between coats, and leave it to dry. Lastly, apply a clear coat, allow it to dry, and buff the area with a polishing buffer.
Every car owner desires to keep their car looking new and shiny for aesthetic purposes and to boost its resale value. Unfortunately, various elements like bird droppings and the sun can blemish your car’s paintwork, making it crack, fade, or even bubble.
Discovering these problems can be quite annoying, hence the need to prevent them from affecting your car paint in the first place. As you’ve seen, there are several types and causes of car paint bubbling.
On the bright side, the issue is relatively easy to fix, but you’ll need the right tools and supplies for the project to be perfect!
Read next: Hair dryer vs heat gun for vinyl application.