Rust on your car's body is a pretty serious concern because, if left unchecked, rust can spread throughout the frame and threaten the structural stability and integrity of your vehicle. Thankfully, if you find rust on your car quickly enough, it only represents an aesthetic problem and can be fixed using some basic tools before it gets the chance to spread.
What You'll Need
Before you get started, you should get all of the materials and tools that you'll be using together to speed up the rust removal process as much as you can. You'll need 150 grit sandpaper, a sanding block or disc, painter's tape, newspaper, auto body primer, two paintbrushes, and auto body paint that matches the color of your vehicle. You can get these items at most automotive and hardware stores – some can even help you match the color of your vehicle to paint that they have in stock.
Removing Auto Body Rust
First things first, you'll want to sand the rusted area in question using the sandpaper and sanding block. Take care to not use too much force, as you can cut into the metal of your car's body. You'll have to sand slightly around the boundaries of the rusted area to ensure that you get rid of all of the rust: don't be too worried about removing excess paint, as you'll be covering it all up soon.
Once the area has been completely sanded and the metal has been exposed, you'll want to cover the edges of the area in question with newspaper held in place with painter's tape.
Use a paintbrush to apply the primer to the newly sanded area. You'll get a better finish if you do several very thin coats, so apply three thin coats with 15 to 20 minutes in between to allow it to dry.
Once the primer has dried, you can apply the actual paint. Paint will take much longer to dry, but should be applied in much the same manner as primer: multiple thin coats. Apply five coats, with a half hour to an hour (depending on the brand of paint) between each coat to allow it to dry. This will leave you with a clean, smooth finish.
Let the paint set overnight, and then wash the entire car with mild cleaning detergent. While you won't have an entirely new paint job, the process should leave your car looking better than it did before.
When to See a Professional
You should head to an auto body specialist if the rust has spread into the body of your vehicle itself. Any sort of actual structural damage can't just be sanded off, as it can have implications on the performance of your entire vehicle. A professional can tell you what your repair options are. Contact a company like Crossroads Collision Center to learn more.