Rust is the silent killer of your car's exterior. It tends to form where there is damage, such as scratched paint from collisions or wear and tear. Rust has three severity levels, with each requiring specific repairs.
1. Surface Rust
The least alarming type of rust to discover on your car is surface rust. This type of rust usually begins near small damages, such as scratches from normal wear or small dents from minor collisions. It may also begin to show up on heavy wear areas, such as at the lip of the car hood where paint first begins to thin or chip away.
If the paint hasn't yet begun to bubble or peel around the rusted area, your auto body shop can quickly repair it. They will sand out the rusted spot until they get to bare metal. For small areas, only touchup paint is needed, while for larger areas the entire panel will need to be repainted. The new paint will guard against future rust formation.
2. Scale Rust
If surface rust isn't treated, it becomes scale rust. The rust penetrates more deeply into the metal body panel and the paint, along with the surface metal, begins to blister and flake off. Once this happens, the rust will begin to spread quickly and it will also increase in severity.
Repair for scale rust is similar to that for surface rust. The affected area is sanded down until no trace of rust remains. A dip or hollow may remain since scale rust penetrates more deeply, so a filler will be applied and buffed to a smooth finish. The panel is then painted and sealed.
3. Penetrating Rust
Penetrating rust comes after scale rust in the level of severity. This is when the rust has eaten all the way through the panel. It's most often found on the underbody of the car, or inside the wheel wells since these areas are exposed to the most moisture. Living in areas with salted winter roads or near the ocean also increases the chances of penetrating rust.
The only way to fix penetrating rust is with a cut and repair. Damaged panels are removed or sections are cut out, then new panels are fitted. Then the entire car is painted so that the newly replaced parts blend in seamlessly with the old.
Contact an auto body shop if you notice any rust on your car. You can avoid severe damage by having it repaired promptly.