Rust is the most widely known name for iron oxide, a reddish-brown oxide formed on iron and steel. It develops when raw metal is exposed to air and the atmosphere, but pure iron doesn’t oxidize as aggressively as alloys. A chemical reaction usually occurs in the presence of water, carbon dioxide present in the air, and a surface impurity, in this case, the carbon present in the steel.
In this article you will find out how to remove surface rust from car paint and tips on how to prevent car from rusting.
Rust begins with isolated spots and spreads over time if you don’t take any action to control it. The process of metal corrosion takes place gradually but can be accelerated or slowed down. The rate at which a surface rusts depends on:
- Temperature, rain, and humidity.
- Nature of metal
- Water drainage
- Alloy component
- Thickness of metal
- Heat treatment
Rusting in Cars
Understanding why rust forms on cars is the first step to preventing it. Rust prevention is a large part of exterior vehicle care.
Where On a Car is Rusting Most Likely to Cccur?
Rust can form anywhere on a metal car but is more likely to appear on areas on the vehicle that are near the road or more exposed to the weather.
Vehicle frame rails are more susceptible to rust because they’re close to the road. They’re also prone to be splashed with water and salt as you drive.
The exhaust system can contact rust and oxidation quickly because of its proximity to the road. The exhaust system comprises thinner metals that spread quickly if not managed well once rusting starts.
Moisture from condensation present in your exhaust system, along with the proximity of the exhaust to the ground, makes this part prone to rusting.
Wheel wells contact a lot of moisture and salt while driving. Manufacturers make these wheel wells with a thin metal, and any rust could quickly turn into holes if not regularly checked.
Suspensions are also susceptible to rust, especially where the suspension conjoins the frame. If not addressed early, rusting in this area could compromise the structural integrity of the whole car.
Since this area is underneath the car, always remove the carpeting and inspect for rust and oxidation.
The bottom part of doors can easily form holes and depreciate since this area is located close to the ground. Regular checkups are essential to prevent rusting here.
Stages of Rusting
Rusting occurs in three stages:
In this first stage, there are no visible signs of rust on the surface of your metal. Your car’s exterior is still in perfect condition, meaning that there are no cracks, foams, or bubbles on the painted surface. Abrasions have not been formed and rust stains or marks have not appeared.
While there is zero repair action required in this stage, it’s essential to enforce measures to ensure that rust will not form on your car’s surface. In this stage, strive to keep the surfaces of your vehicle as clean as possible and keep it away from potential abrasives. Ensure that you remove oils, dirt, and solvents to prevent the breaking down of the protective coatings.
This stage denotes a superficial problem that requires attention to ensure that it doesn’t escalate into a worse state. In this stage, your car’s surface retains its smoothness but will begin to show rust-colored deposits, which may be white, black, or red.
While the base metal of your car remains relatively undamaged, cracking or foaming appears on the surface. In this stage, you should consider beginning repairs to ensure the rust does not spread to the surface.
In this stage, scale begins to form on the surface of your car. Scaling happens after you neglect the surface and there’s continued exposure to the agents of rusting. The surface is usually rusty red, with white or black corrosions. The surface loses its smoothness to perforations and wears out.
When all the surface particles that form red iron oxides have been involved and are in powder form, the rusting powder falls off, leaving a darker metal color.
Signs of Rust
There are minor, subtle signs that will indicate the onset of rusting on your car. You’ll start seeing the first signs on the surface.
These begin to form on the surface of your car. Bubbles may also appear as scattering bumps along the segment of the paint. The paint on the surface starts to lose its attachment to the car’s surface because water and air collect and oxidize it.
This indicates dampness or water damage and usually signifies that the metal beneath has rusted.
This appears because the wax and paint, that act as a protective barrier for the surface, scrapes off from different points on the car.
Nicks and dents are usually visible on the surface.
Spots and strips of paint that do not match the car’s original color become visible. Look at the surface in the sunlight to ascertain the rough, flaking presence of rust.
Types of Rust
Seeing rust on the surface is the first sign of rusting that usually appears in the paint. Over time, the top clear coating of your car’s paint wears off, and this kind of rust leaves the paint exposed to wear and abrasions. When moisture seeps in through such openings and penetrates the unprotected metal, the process of rusting begins.
Pure iron cannot be used for building cars, so steel alloys are used. This comes about by adding a dollop of carbon to iron to make steel. This is because steel is better in flexibility and formability and has a tensile strength, providing a better body for your car than pure iron.
The carbon added to the iron is an impurity. As much as it improves the quality of the iron, carbon, and any other impurities added, accelerates the rusting process of such metals.
Scale rust appears when you don’t correct surface rust. When rust penetrates the surface of your metal, it forms a rough, pitted type of damage called scale. Scale corrupts the surface of the metal and reduces the metal’s strength, making it more susceptible to oxidation.
Factors such as the thickness of steel, its environment, type of heating treatment, and alloys present will dictate how fast it will rust. Rust affects iron, and any alloy with the metal present will experience rust.
This type of rust usually occurs on exposed steel.
Penetrating rust is the most severe rust type resulting from prolonged steel exposure to elements. This rust damages the structure of your vehicle and compromises your vehicle’s longevity.
Here, the oxidized steel usually degrades to become brittle iron oxide with holes formed on the sheets. This rust is generally preventable if caught early. Once this happens, your only option is to replace the affected panel completely. If it is a body issue, you can carve out the rotten parts and weld them on patch panels to repair them.
This requires help from a professional body shop since the structural integrity of your car is at stake.
How To Remove Surface Rust From Car Paint
Minor surface rust that’s not penetrative doesn’t require professional panel welding work and you can turn it into a DIY project from the comfort of your house. The process is beginner to intermediate friendly.
You should adopt safety measures to protect yourself and the surface you are working on from damage.
For safety purposes, ensure that you have:
- Mechanical gloves: to protect your hands from bare metal, chips, and corrosive solvents.
- Safety glasses: to protect you from rust fragments and paint chips that can cause eye damage.
- A respirator: to prevent you from inhaling harmful vapors
- Long-sleeved shirt: to protect your arms
You will need:
- Sandpaper in different grits
- Hand scraper
- Sanding disc
- Grinding tools
- Automotive soap
- Paint and clear coat
- Rust removal spray
- Masking tape
- Several microfiber cloths
Identify a flat surface where you will be able to work comfortably. The area must have enough ventilation to let in as much fresh air as possible.
1. Wash the Affected Area with Automotive Soap
Washing the surface removes any adhering oils, dirt, or other contaminants.
Dry the area before proceeding to the next step.
2. Tape off the Area
Taping is an easy way to prevent rust from spreading. Taping will also ensure that the surrounding areas are protected from accidental contamination by paint and solvents.
You can use different types of tape, but look out for those with too much adhesive as they may pull paint from your vehicle’s surface. The best tape to go for would be painter’s tape or masking tape.
3. Removing Paint and Primer from Your Car
To ensure the effective removal of rust from the surface, start by removing paint and primer from the section.
Sand off the paint and primer manually using a sheet of sandpaper. Begin with low grit sandpaper and gradually move to a high grit one. If available, you may also opt to use a sander where you might want to use at least three different grits of sandpaper at a time.
We recommend that you start with an 80 grit sandpaper and work towards a 150 grit.
4. Scrap off the Rust
You can choose a rust removal method that will suit you. You can opt for sandpaper depending on the intensity of the rust. If caught in the early stages, even better, the problem comes in if the rust is advanced.
You will need to put in a lot of elbow grease or opt to use a power tool if the rust is too advanced.
The other tool to consider is an abrasive wheel or a metal grinder. Take caution when using these tools, as they can cause more damage to the underlying metal.
There are also rust removal sprays available in the market, in which case you should follow the instructions given and then proceed with sandpaper.
Once you have chosen your tool, continue to sand down the area until you reach a clean metal.
5. Wash the Area with a Degreasing Agent or Soap
This step ensures the removal of any residual rust powder, grease, or products. Rinse and dry once complete.
6. Wipe Down with IPA Solution (Optional)
To ensure that the area is thoroughly clean, you can wipe the area with a pre-paint applicator. A 30/70 dilution of Isopropyl Alcohol with distilled water, sprayed on a clean microfiber towel, will give you a clean canvas to paint.
7. New Primer and Paint
Ensure that the area to be painted is even and smooth before proceeding. Research the primer and paint you want to use since there are different products and the quality varies.
We recommend using a primer to ensure the paint adheres to your car’s surface, making for a cleaner finish.
Coat the area with primer carefully and evenly for a smoother finish. Wait for it to dry and check for any imperfections, which you can sand down before painting.
Apply the paint across the area and wait for it to dry before proceeding. Ensure that the coat is even and smooth before applying the next coat.
Once satisfactory, add a clear coat layer that acts as a paint protector to ensure that the area has extra shine.
Remember to sand, clean, paint, and dry with every subsequent layer of paint.
Preventive Measures Against Rusting
Storing Your Car in Good Condition
Good storage is especially beneficial for those living in areas that have salty air. Keeping your car in the garage and covering it with a carport will go a long way in protecting your vehicle from rusting.
Washing Your Car Regularly
Consistent car washes will ensure that your car’s surface has no components that aid in rusting. If your area uses salt for icy roads, ensure that you wash your car often to prevent the buildup of salt which will accelerate the rusting.
After washing, ensure you have dried your car thoroughly.
Removing Surface Rust
Being proactive in dealing with surface rust as soon as it occurs will ensure that you have stopped severe types of rusting from happening.
Annual Oiling with a Rust Proofing Spray
This preventive measure is especially for those who need to protect their cars against road salt that causes rust.
While there are numerous methods to prevent rust from attacking the surface of your car, rust is a common issue that affects many people. Remember to keep your car clean and frequently check your vehicle for surface rust. This will prevent it from advancing into the more severe and expensive repair stage of rust.