Rust is a car owner’s nightmare. Knowing that corrosion is slowly eating away at your vehicle can be disheartening. If left unchecked, rust can severely damage your car, potentially reducing it to scrap. The good news is that modern cars have factory rust protection. Rust typically appears later in a vehicle’s life due to wear and tear or damage that compromises this protective layer, leaving your car vulnerable to corrosion. At this point, you might start worrying about the hefty bill from a body shop to fix it. And yes, professional rust repair can be expensive.
However, don’t despair! If you’re willing to tackle the job yourself, you can effectively stop rust in its tracks and significantly extend the lifespan of your car. It’s a manageable task that primarily requires thoroughness and doing it correctly.
How Much Can You Save by DIY Rust Repair?
You may have already explored DIY solutions for minor car scratches. Rust repair is the next level, and professional rust removal and repair can easily cost hundreds, if not thousands, depending on the extent of the damage and the number of panels affected.
By taking on the rust repair yourself, you can save a considerable amount of money, mainly covering the cost of the necessary tools and materials.
Before we dive into the process, let’s clarify a few key points:
Focusing on Surface Rust
This guide is specifically for surface rust. If the rust has progressed to the point of creating holes in your car’s body, floors, sills, or chassis, then professional intervention and welding are likely required. We are addressing corrosion that is affecting the panels but hasn’t yet compromised the structural integrity of your vehicle.
Paint Considerations
This guide will cover the repair process up to the priming stage. If you’re comfortable painting, you can certainly proceed with applying the color coat. Solid colors are generally easier to achieve good results with, while metallic paints can be more challenging to blend seamlessly.
There’s no shame in completing the rust repair preparation and then having a professional body shop handle the painting and blending. Professional spray equipment is designed for this purpose, offering a level of finish that aerosol cans often can’t match.
Step-by-Step Guide: How to Repair Rust on Your Car
While cars today are significantly more rust-resistant than vehicles from just two decades ago, living near the coast or in regions where road salt is used during winter can still lead to rust formation well before the mechanical components wear out.
Minor rust damage on non-structural parts is readily repairable. With some patience and practice, you can achieve a repair that makes the rust seem like it never existed.
Professionals restoring classic cars often opt for cutting out the rusted section and welding in new metal. However, for a daily driver, using fiberglass epoxy and body filler is a much simpler and effective approach for surface rust.
We’ve previously discussed fixing car scratches, but what if a scratch has progressed to rust? Often, rust starts from minor paint damage, such as a chip from road debris or a door ding that cracks the paint. This is why regular car washing and inspections are crucial. A quick touch-up with paint can prevent hours of rust repair work in the future.
Follow these step-by-step instructions to repair rust damage on your car:
Tools and Materials You’ll Need:
- Angle grinder with flapper wheels (various grits)
- Wire brush (steel and nylon)
- Fiberglass epoxy gel or paste
- Body filler (automotive filler)
- Sandpaper (various grits: 80, 120, 240, 320, 400, 600, 800, 1000, 1500, 2000)
- Sanding block (rubber or foam)
- Automotive primer (rust inhibiting)
- Base coat car paint (matching your car’s color code)
- 2k clear coat paint (aerosol cans are suitable)
- Masking tape and paper
- Rubbing compound
- Polishing compound
- Mineral spirits or wax and grease remover
- Microfiber rags
- Tack cloth
- Safety glasses
- Gloves
- Dust mask or respirator
Step 1: Preparation and Safety
Before starting, gather all your tools and materials. Work in a well-ventilated area or outdoors. Wear safety glasses, gloves, and a dust mask or respirator to protect yourself from dust and fumes. Clean the area around the rust with soap and water, then dry thoroughly. Use mineral spirits or wax and grease remover to eliminate any wax or grease that could interfere with the repair process. Mask off the area surrounding the rust with masking tape and paper to protect the surrounding paint from accidental damage during sanding and grinding.
Step 2: Removing the Rust
This is the most crucial step. You need to remove all traces of rust to prevent it from spreading. Start with a wire brush to remove loose rust particles. For more stubborn rust, use an angle grinder with a flapper wheel. Begin with a coarser grit flapper wheel (e.g., 80 grit) to aggressively remove the rust. Work outwards from the center of the rust spot, being careful not to grind away too much of the surrounding good metal. The goal is to remove all visible rust and get down to clean, bare metal. Switch to progressively finer grit flapper wheels (e.g., 120, 240) to smooth out the surface and remove grinder marks.
Step 3: Treating the Bare Metal
Once you’ve removed the rust and have bare metal, it’s important to treat the metal to prevent future rust formation. Apply a rust converter or rust inhibitor to the bare metal according to the product instructions. This will chemically neutralize any remaining rust and create a protective layer. Allow it to dry completely.
Step 4: Applying Fiberglass Epoxy
For shallow rust damage, you might be able to skip this step and go straight to body filler. However, for areas where the rust has created some pitting or thinning of the metal, fiberglass epoxy provides excellent strength and waterproofing. Mix the fiberglass epoxy according to the manufacturer’s instructions. Apply a thin layer of fiberglass epoxy over the bare metal, extending slightly beyond the repair area. This will create a solid, waterproof base for the body filler. Let the epoxy cure completely as per the product instructions.
Step 5: Body Filler Application and Shaping
Once the fiberglass epoxy is cured (if used), or directly onto the treated bare metal, it’s time to apply body filler. Mix the body filler with the hardener as instructed. Apply a thin layer of body filler using a plastic spreader, pressing it firmly into the repair area. Apply in thin layers, building up gradually. It’s better to apply multiple thin layers than one thick layer, as thin layers are less likely to crack and are easier to shape. Allow each layer to partially harden before applying the next.
Once the body filler is fully cured, begin shaping it using sandpaper and a sanding block. Start with a coarser grit sandpaper (e.g., 80 grit) to roughly shape the filler to match the contours of the surrounding panel. As you get closer to the desired shape, switch to finer grits (e.g., 120, 240, 320, 400) to refine the shape and smooth out the surface. Regularly check your work by running your hand over the repaired area to feel for any imperfections. Aim for a smooth, seamless transition between the filler and the original panel.
Step 6: Priming
Once you are satisfied with the shape and smoothness of the body filler, it’s time to apply primer. Clean the repair area with a tack cloth to remove any sanding dust. Apply several thin coats of automotive primer, allowing each coat to flash dry according to the primer instructions. Primer provides a uniform surface for the paint to adhere to and also helps to reveal any imperfections in the body filler. After the primer is dry, lightly sand it with fine-grit sandpaper (e.g., 400 or 600 grit) to smooth out any primer texture and remove any imperfections.
Step 7: Painting and Clear Coat
Clean the primed area with a tack cloth. Apply several thin coats of your base coat car paint, following the paint manufacturer’s instructions for drying times between coats. For best results, apply multiple thin coats rather than one thick coat to avoid runs. Once the base coat is dry, apply several coats of 2k clear coat for protection and shine. Again, apply thin coats and allow proper drying time.
Step 8: Blending and Polishing
After the clear coat is fully cured (usually 24-48 hours), you can blend the repaired area into the surrounding paint. If there is a noticeable edge where the new clear coat meets the old paint, you can use very fine grit sandpaper (e.g., 1500 or 2000 grit) and water to lightly sand the edge and blend it in. Then, use rubbing compound to remove the sanding scratches and level the clear coat. Follow up with polishing compound to restore the shine and achieve a seamless finish. Finally, apply a good quality car wax to protect your newly repaired area.
Tools and Materials Checklist:
- Angle grinder & Flapper wheels (80, 120, 240 grit)
- Wire brush
- Fiberglass epoxy gel
- Body filler
- Sandpaper (80, 120, 240, 320, 400, 600, 800, 1000, 1500, 2000 grit)
- Sanding block
- Primer
- Base coat paint (car color matched)
- 2k Clear coat
- Masking tape & paper
- Rubbing compound
- Polishing compound
- Mineral spirits/Wax & Grease remover
- Rags
- Tack cloth
- Safety glasses
- Gloves
- Dust mask/Respirator
Repairing car rust yourself is a rewarding process that can save you a significant amount of money and extend the life of your vehicle. By following these steps carefully and taking your time, you can effectively eliminate rust and restore your car’s appearance. Remember to always prioritize safety and use the appropriate protective gear. With a bit of effort, you can confidently tackle surface rust and keep your car looking its best for years to come.
