A Step-By-Step Guide to Getting Rust Off Your Car

Why do vehicles rust?

Cars rust due to a simple (but powerful!) chemical reaction: oxidation, which occurs when iron is exposed to oxygen and moisture. The metals vehicles are made of, especially steel and iron, react to form a new compound: iron oxide, commonly known as rust. Cars with aluminum or plastic panels might rust more slowly or not at all, but steel frames, undercarriages, and suspension components will still rust. 

Some cars are more likely to rust than others. Humidity, snow, and rain accelerate the oxidation process by increasing the presence of moisture, and older vehicles are generally more vulnerable to rust.  As rust forms, it expands and puts pressure on the surrounding paint and primer. This exposes fresh metal, which the rust then spreads to. 

Three kinds of rust

Rust doesn’t come in just one form. It actually evolves in stages, each of which poses a greater threat to your vehicle than the last.

• Surface rust: The first, most common, and most treatable form of rust is characterized by mild discoloration.
• Scale rust: Scale rust is what appears if you don’t take care of surface rust, and it’s often characterized by flaking and a rough texture.
• Penetrating rust: Sometimes called structural rust, penetrating rust is the most concerning. It means the rust has cut through the metal and formed readily apparent holes.

How can rust harm your vehicle?

When rust penetrates beyond the surface of a vehicle and begins to eat into its structure, it becomes far more hazardous. Rust can weaken your vehicle’s frame, subframe, and other load-bearing structures, rendering them more fragile and susceptible to further damage. 

Rust also takes a toll on suspension parts, such as shock towers, springs, and control arms, which can inhibit handling and reduce your control behind the wheel. Furthermore, rust can damage other critical components, such as brake lines, fuel tanks, brake pads, battery terminals, body panels, and wheel wells, which are particularly susceptible to rust due to their consistent exposure to moisture. 

When these parts become corroded, they don’t work as well. In severe cases, a bad case of rust can lead to brake failure, fuel leaks, and other dangerous safety issues.  Your rusted vehicle might still get you from point A to point B, but it will harm your car over time if you allow the rust to continue spreading.

How to remove rust from your car

Before we get started, it’s important to note that not all rust should be handled as a DIY project.

If rust has already progressed beyond surface rust and you notice bubbling, cracking, peeling, blistering, or impacts to the vehicle’s suspension components and structural integrity, consider taking the vehicle into an automotive repair shop for professional help instead.

The deeper rust penetrates metal, the harder it becomes to reverse, so removing it may not even be possible in certain circumstances. Some signs that rust is too far gone for treatment include visible holes, frame sagging, soft spots on the underfloor, paint bubbling/blistering/flaking, and widespread rust that’s not confined to isolated spots. 

Before attempting to remove rust on your own, put on eye protection, a long-sleeved shirt, pants, and a dust mask to protect yourself from flying dust, metal, or chemical particles. To protect your hands from chemicals and sharp metal, wear heavy-duty gloves suited for hands-on work. Once you’re safe and prepared, you can proceed with the rust removal process: 

• Step 1: Tape off the area of the vehicle that needs attention, protecting the non-rusted areas from the chemical, rust, and metal particles that may fly into the air during this process. 
• Step 2: ​​Use a wax and grease remover on a clean cloth to remove contaminants, oils, or residue that can interfere with repairs by preventing paint and primer from adhering correctly.
• Step 3: Next, uncover bare, unaffected metal underneath the rusty areas using a sanding block, sandpaper, or a wire brush. Remove not only rust but also the surrounding paint and primer.
  This step is crucial because if you miss hidden rust, it might continue to spread. 
• Step 4: Verify that all rust has been removed (including small pits, crevices, etc.) by using grinders or drills that include wire wheels or a chemical rust remover.
• Step 5: Once the bare metal is exposed, use the sanding technique known as “feathering,” in which you gradually blend the edges so that the bare metal transitions smoothly into the surrounding paint. Continue feathering until there’s no noticeable difference in texture between the bare metal and the surrounding paint.
• Step 6: Once you’ve cleaned and revealed the bare metal, you must take action to avoid flash rust, a kind of rapidly forming rust. Use a rust converter, a chemical solution that utilizes organic polymers and tannic acid to transform rust into iron tannate, thereby stabilizing the metal and preventing further corrosion. 
• Step 7: Apply primer to the area. This will help the paint you add next stick better, plus it gives your vehicle extra protection from elements like moisture and oxygen that could cause it to rust again. Add the primer gradually, layering on several thin coats and waiting about 5-10 minutes between layers. 
• Step 8: Use a paint the color of your car to add a base coat, which should be thin and applied evenly. Instead of just moving the brush from edge-to-edge once, make sure each new stroke also covers about half of the previous stroke.
• Step 9: After allowing the paint to dry for about 10-15 minutes to achieve a matte texture, you can begin adding additional coats. Keep adding coats of paint until it conceals the primer and mixes well with the surrounding paint. To achieve a blend that looks natural, you’ll want to paint a bit outside the primed spot and into the vehicle’s original coat of paint.

Hit the road with Transwest

At Transwest, we have plenty of great cars from the industry’s greatest brands. Stop by today or browse our inventory to find your next car, and visit one of our service shops if you need a repair.