Rust is an inevitability that can prematurely retire your vehicle if left ignored and untreated. Knowing the signs and dealing with rust as it arises can save you a lot of money, time, and effort in the long run, so we’ve put together this handy step-by-step guide to help you do so.
And if you don’t already have a rust bucket in your garage, we’ll also provide valuable information on how to keep it that way by preventing rust from forming. Read to the end for a list of tools and supplies you’ll need, as well as a few of the best products for car rust removal that we’ve found based on intensive market research.
What Is Rust and How Does it Occur?
You’ve probably come across rust at some point in your life. The brown and flaky substance can be found on numerous metal surfaces worldwide, perhaps most notably on our cars. Rust is formed in a process known scientifically as oxidation, which Popular Mechanics defines as taking place when “iron surface molecules react with oxygen in the environment and produce a new molecule, Fe2O3, otherwise known as iron oxide. That iron oxide is rust.”
Iron typically rusts quite slowly, but it isn’t a great material for constructing a car. Instead, cars are made using steel alloys to increase flexibility and decrease the weight of modern vehicles. This more suitable construction material comes at a cost–it rusts at a much faster rate. Obviously, you don’t see every car on the road covered in rust after a few years. This is because of the durable coatings that are applied during production. These still aren’t a match for our cars’ everyday wear-and-tear during our daily commutes, so these coatings will eventually corrode in some spots.
Other factors can contribute to the formation of rust on your vehicle. For example, if your car is hit or scratched, it can scrape off its paint to expose the metal underneath, creating areas vulnerable to oxidation effects. Drivers who live by the ocean can also expect the coatings on their cars to wear off more quickly with exposure to salty air blowing in from the water. Salt can also speed up rust formation in colder regions–if road salt is used regularly in your area, it can also wear your paint and coatings off at a higher-than-average rate.
It’s also important to distinguish between the two most common types of rust on a car:
- Surface rust: This type of rust occurs on many metals when they are left unattended, and it is usually not a major issue.
- Penetrating rust: This is the type of rust you’ll want to be more concerned about. Unlike surface rust, which can usually be wiped away, penetrating rust can eat away at the metal and even go as far as to put holes in it.
In this post, we’ll just be covering how to repair surface rust–that is, before it gets to the stage where your car looks like a block of Swiss cheese!
Tools and Supplies You’ll Need to Fix Rust on a Car
First, you’ll want to get started by gathering everything you’ll need to get the job done:
- Automotive touch-up paint: To match your paint code, check the engine compartment or the trunk or use an online search engine.
- Aerosol cans or rollerball applicators: The Family Handyman recommends these application methods over spray guns because “even if you know how to use a spray gun, mixing automotive paint with a reducer to match the temperature and humidity conditions can be mighty tricky.” It’s easier to use aerosol cans for more extensive repairs and rollerball applicators to repair minor scratches.
- Base coat and clear coat: Your vehicle’s base coat is the color of the paint, while the clear coat is the glossy finish that goes over it. Make sure you buy equal parts of both so you don’t run short.
- Primer: You’ll need two different types of primer to get the paint to stick to your vehicle. First, you need an epoxy primer that can catch on the metal. Next, get a lacquer primer to which the rest of the paint can bond.
- Sanding: Most of us don’t have access to a power sander or sandblaster that’s rated for use on vehicles. If you do, all the better–but for most automobile applications, you’ll need low, medium, and high-grit sandpaper and a sanding block. However, if you’re looking for an excuse to buy a new toy, a solid portable sander can make some bigger jobs much easier.
- Painting supplies: We’ve already covered a few of the implements you can use to apply paint, but there are a couple of ways to protect the rest of your vehicle. Attach poly sheeting or newspapers to your car with blue painter’s tape, covering the parts of the car that you’re not working on. This can save you significant effort, as the dust from sanding and the paints and primers being sprayed can be a pain to clean off.
- Grease and wax remover: Even with all the right precautions, you may still find yourself in a situation where you’ve gotten paint, lacquer, or epoxy somewhere it shouldn’t be. Save yourself an extra trip to the store and keep some grease and wax remover nearby.
- Microfiber and tack cloth: Even when you take all the necessary precautions, the amount of sanding you’ll be doing will create tons of dust. Using poly sheeting should keep your cleanup to a minimum, while microfiber and tack cloths will take care of the rest and prepare you for painting.
How to Resolve Car Rust
Now that you’ve gathered all the necessary materials, it’s time to tackle that pesky rust! Make sure that when you’re planning this project, you give yourself plenty of time. Most of what makes this process take a little longer is waiting for all the paints and coatings to dry–you want your car covered and off the road during that time. Ready? Let’s get started with the step-by-step instructions:
1. Isolate your work area: Cover the surface area of your car with poly sheeting and secure it with painter’s tape, only excluding the rust spot and its immediate surrounding area. If you’re working on a wheel well, you may want to remove the tire entirely to increase access.
2. Begin removing the rust: Start by cracking off any heavier pieces with a scraper or gloved hand. Next, use your low-grit sandpaper to sand down rust spots to the bare metal. Proceed to the medium grit sandpaper and begin to feather out the edges, removing paint and exposing more metal. Lastly, use your highest-grit sandpaper to sand everything smoothly.
3. Prep for painting: You should now have a smooth metal area without any rust or paint. It may still be a little dirty, so use a tack cloth to remove any dust. To get things totally clean for painting, you’ll need to clean them with a grease-cutting detergent and clean water. Follow the manufacturer’s instructions on your primer if you have any questions.
4. Epoxy and primer: If you’re dealing with rust that has penetrated so far as to create indentations/holes in the surface, you’ll need to fill them before moving forward. Apply the epoxy primer first and wait for it to dry. Follow it up with the filler primer, using thicker coats. You’ll want to follow the instructions on the bottle, but it will typically be two to three coats with appropriate dry time in between. If necessary, you may need to sand and apply another layer of lacquer primer.
5. Time to paint: All that’s left to do is follow the instructions on your top coat and clear coat. We recommend letting your car dry for at least 48 hours after applying your last coat of paint. After that, simply buff it out with a microfiber cloth and wait as long as the manufacturer recommends before giving it a good wax.
How to Stop Rust From Forming
If you’ve just finished removing rust and painting your car, you’re probably wondering what you can do to ensure you don’t ever have to do that again. The simplest answer is to make sure you’re keeping your car clean and taking care of body damage before it turns into rust. Going to the car wash every couple of weeks is a good way to make sure that the underside of your car is getting taken care of and adequately cleaned.
There is one other precaution you can take: Popular Mechanics recommends that you check the bottom of your car doors and rocker panels for rainwater drain holes and clean them out: “Use a pipe cleaner to clear these holes out, and keep the car’s nooks and crannies dry. WD-40 can be a useful tool here as well. This lubricant protects parts from corrosion, and its thin nozzle can be used to reach tight underbody spots and blast away water or corrosive grime.”
Products We Recommend to Fix Rust on a Car
Here are a few of the best products we’ve found for fixing rust on your car:
POR-15 Stop Rust Kit
If you are working on a budget, only need to de-rust a small area, or don’t already have many of the required materials on the list, we recommend finding a kit that contains everything you need. Thankfully, POR-15 makes an amazing kit that has you covered for up to a six-foot space. For under $30, you’ll have the tools needed to clean, prep, and coat the metal with a rust-preventative “hammer tough” finish. You won’t find a better value for eradicating a rust spot and getting it ready to paint.
One Amazon reviewer who used this product on his vehicle said: “We bought an old van in good mechanical shape. However, the body had a few significant rust spots. So, I asked questions and did research and chose this product. I also watched a few videos on how to use the products. What were terrible rusted out spots are now fully protected from further spread of the rusting. I hope to do further work so I can paint the areas, but that can wait since I have arrested the rust.” The other reviews are similar, so it’s safe to say that this is a useful and effective rust-removal kit.
TCP Global Painter’s Grade Tack Cloths
The fabric in Pure Blue tack cloths is micro-apertured to trap, pick up and remove all the surface particles and contaminants, leaving you with an exceptionally clean surface that's necessary when you're preparing for car painting or for woodworking varnish finishing.
Getting rid of the rust is really only the first step if you want to restore your car to its former glory. Having a tack cloth on hand that can properly clean and remove static is essential to that process. Try TCP Global’s wax- and silicone-free tack cloths for the best value and quality. They’re painter’s grade, meaning they’re designed for finishing professionals–use these to get your surface perfectly prepped for lacquer finishes or paint. The cloths’ subtle stickiness makes them great for all sorts of cleanup jobs where you need to be absolutely sure there’s no debris left behind.
STA-BIL Rust Stopper
Prevents rust and corrosion - Fights the formation of rust and corrosion on exposed metal surfaces; Multiple uses and applications for farm, boat and marine, chainsaw, snowplows, bike and motorcycle chains, garden equipment, truck, industrial, car and automotive; Works on electrical components and painted surfaces
For those of you seeking the best products to prevent rust, try out Rust Stopper by STA-BIL. This is an excellent alternative to WD-40 since it also has that handy little nozzle that can get into all the tight spaces in your wheel wells and undercarriages. It even leaves a film surface behind that is proven to withstand harsh weather and road conditions. It’s super easy to use, so you’ll find yourself putting this on just about everything that’s recommended on the bottle!