Last Updated on August 25, 2023 by Chase Manhattan
Rust bubbles on the car paint are a thing to worry about. Feared among car owners, rust bubbles can spread to the rest of the paint job. The proper solution is to take the car to a repair shop. However, you can stop the bubbles from spreading until you repair the paint.
Here is how to stop rust bubbles from spreading on your car:
- Get Rust blaster oil(penetrating catalyst)
- Get a needle with a tube.
- Put the oil in the tube.
- Pop the bubbles from the top.
- Inject the rust blaster.
We will also talk about how to solve the issue once and for all.
If you don’t know what you are doing, you are going to do more harm than good. So, read and follow this step-by-step guide.
Treating Car Paint With Rust Bubbles
The rust removal depends on how bad the situation is. So, the fixes you find here will not necessarily work on your car. The best and smartest thing to do is take your car to a professional.
I get it that these detailing procedures can be quite expensive. Especially when it comes to rust repair. That’s why I am offering you temporary solutions. First, we have to assess the rust situation.
- Type of rust.
How much of the paint is affected by rust is something to take into account. The common rust spots(scale rust) won’t spread, so you are going to wait for the body shop rust repairs. Rust bubbles, on the other hand, you will have to stop from spreading.
- Power Tools.
Repairing rust paint requires power tools and expertise. My guess is the majority of you don’t have the needed tools. So, you need to take your car to the body shop for any rust issue, both for major repair and minor surface rust. All types of rust should be handled by a professional, even scale rust.
- Type of car.
Now, the type of car you own is another thing to think of. New, expensive cars, you can’t really repair on your own. Old cars with plain car paint, you can probably fix on your own, even without using power tools.
To sum all of this up, my advice is, to just stop the rust bubbles from spreading until you can take the car to the body shop. On old cars with plain body paint, you can fix the issue on your own. Brand-new cars with a specific type of paint should be taken to the body shop.
Related article: What Is Clear Coat?
Stopping Rust Bubbles From Spreading On Car Paint
[Recommended Read: 6 Common Causes of Car Scratches That Piss You Off]
Before we start, you should know. This is a solution for cars that only have a rust bubble or two on only one part of the paint job. What I’m saying is that you can’t really stop rust that has spread all over the hood for instance.
Think of this as a rust preventative step. If an entire body panel of the paint has corroded, you must take the car to the body shop. There’s nothing you can do anymore. Up to a quarter panel can be saved, even that’s too much.
Now that we got that out of the way, we can start with the step-by-step guide. Remember, take your car to be repaired after the financial situation allows you to.
- Get rust penetrating oil.
A really quick way to get rid of rust and stop it from spreading is a penetrating catalyst. This is a product that usually comes in a spray bottle or as an oil. Go for the oil here. The rust blaster destroys the rust and stops the corrosion process. There are plenty of products you can choose from, I recommend B’laster Penetrating Catalyst.
- Get a needle with a tube.
- Put the penetrating rust oil in the tube.
Most of these oils come with a tube for application. But you want to burst the bubble and get inside it. So, a needle works best here.
- Burst the bubble with the needle.
Start from the top of the bubble. You are going to inject the oil. It will flow to the bottom, that way you cover all of it. If it’s a whole spot with bubbles, burst from the top, from left to right. If you can’t pop the bubble. Don’t push the needle too much, just twist it against the paint.
- Inject the oil.
Just slowly push the thing on top of the tube. Don’t spray too much. And, always inject from the top, so the oil can flow to the rest of the bubble.
- Try to avoid unaffected paint as much as possible.
There you go, this will stop the rust from spreading. Take your car for paint repair as soon as possible. Here’s a video too, they explain this method well.
How To Repair Car Paint With Rust Bubbles
There are two ways to do this, with and without power tools. Old cars with plain paint can be repaired without using power tools. For relatively new cars, I mean past 2000, it’s best to use power tools. You will not be able to match the paint finish without an electric buffer.
Repairing Rust Bubbles Without Power Tools
- Grit Sandpaper
- Masking Tape
- Masking Paper
- Rust Converter(Rust Inhibitor)
- Aerosol Primer
- Correct Color Car Paint
- Optional: Body Filler
Keep in mind, this is a temporary solution. The rust may reappear after a year or two. During that time, collect money for a body shop repair.
1. Sand The Area With Bubbles
First, you need to remove the rust bubbles and the surface rust. To do that, use 60 grit sandpaper. Just give it a nice sanding, remove the bubbles, and make the affected area smooth.
There will still be some loose and surface rust. Give it sanding with finer sandpaper. When you are done, the rust should be gone, and you should be left with a bright metal surface.
2. Apply Rust Converter
Dip a paint brush in the rust converter(rust inhibitor) and apply it to the sanded area. Do it nice and slow, make sure you cover every inch and square.
3. Optional: Apply Body Filler
Do you see any holes in the affected area? Did the corrosion eat through the paint and the metal surface? If you have any holes you can fix them with body filler. Just make a mixture of the body filler and the harder, and fill any rust holes.
4. Sand With 20 Grit Sandpaper
Once again, thoroughly sand the area you applied the rust converter and the body filler on. It’s best to use a sanding block here or a piece of wood to keep the level. Switch to a finer grit once you reach a relatively smooth surface.
5. Apply Automotive Body Filler
Mix the standard body filler with a hardener. This time, apply it to the whole area you have sanded before. This is not to fill up holes but to bring the rusted area to level with the rest of the paint.
6. Sand Again
Once you are done with the body filler, continue with the sanding process. Use a finer grit here to reach a finer finish.
7. Clean The Area
To remove any surface dirt, clean the area with a soft towel or MiracleWipes.
8. Apply Primer
Apply a coat of aerosol primer. Add several coats. Do a line by line so you will have a uniform finish.
9. Let The Primer Dry
10. Sand Again And Keep Wet
Put some water in a spray bottle and get 160 grit sandpaper. Continue with the sanding process while keeping the primer wet with the spray bottle. Stop once you have a smooth finish.
11. Clean The Area Again
12. Apply Automotive Paint
Here is where you restore your car’s paint. Apply the automotive paint coat by coat. Use light coats to start with. Then, do three heavy coats. And, finish with three more light coats.
13. Optional: Apply Clear Coat
To help visualize things, here’s a video on how to do this properly. The explanation is simple and clear.
Repairing Rust Bubbles With Power Tools
You Will Need
- Electric Buffer
- Multiple Sandpaper Fine Grit & Hard
- Wax & Grease Remover
- Masking Tape
- Body Filler
- Correct Car Color Paint
- Primer For Filler And For Paint
- Cutting Compound
- Mixing Board
- Microfiber Cloth
- Wire Brush
- Sanding Block
1. Prep The Area
You need to work on a clean surface, use wax & grease to clean off any road salts, road grime, and wax.
2. Protect Unaffected Paint With Masking Tape
3. Sand The Area With 80 Grit Sandpaper On A Buffer
Remove any rust bubbles and rust spots.
4. Apply The Body Filler
Mix body filler and hardener on a mixing board. Apply the body filler over the area.
5. Sand Again With 80 Grit Sandpaper On A Buffer
6. Apply Primer
7. Sand With 400 & 600 Grit Sandpaper
8. Apply Paint
The procedure depends on what kind of paint you are using. Follow the instructions for your type of paint.
9. Apply Paint Finish & Light Coat
First apply paint finish, once dried, apply a light coat.
What Causes Rust Bubbles On Car Paint
Now you know how to temporarily fix rust bubbles on a car. However, do you know why the bubbles appeared in the first place? This is crucial if you want to prevent any corrosion on your car.
Rust is the result of the corrosion process on the paint job. It can appear in spots and bubbles. Rust bubbles are formed when the paint film separates from the metal surface. If not stopped, the rust will continue to spread because it’s under the paint. There is nothing to protect the paint anymore.
This happens when a car has stayed in direct sunlight too long. Or, when it has been exposed to high heat. Moisture can also cause this. Usually, rust bubbles are a sign of a neglected car.
Related Questions And Other FAQs
How Do You Stop A Small Rust Spot From Spreading
There is no permanent solution except taking your car to body shop repair. Rust penetrating spray can stop the spot from spreading but only for a while.
Does WD-40 Remove Rust
Yes, WD-40 can stop a rust spot from spreading but it can’t fix the rust spot. Use WD-40 only to stop rust from spreading, not to fix the rust paint.
Does WD40 Hurt Car Paint
No, WD40 does not hurt car paint. It is a solvent that will help you remove any stubborn stains, and will leave a residue, but it will not damage your paint. It will however remove any wax that you’ve applied to your car.
How Fast Does Rust Spread
It’s impossible to say how fast rust will spread, but environmental conditions play a large factor. If the vehicle is left in wet conditions that initially caused the rust, the rest may spread faster. If the car has been removed from the environment that caused the rust, it may take longer for the rust to spread.