How to Do Auto Body Repair Rust: A Step-by-Step Guide

Rust is a car owner’s nightmare. If ignored, this corrosive menace can spread rapidly, turning your prized vehicle into a heap of junk. While cars come with factory rust protection, daily use and accidental damage can expose the metal underneath, leading to corrosion. A visit to a body shop for rust repair can be expensive, often costing hundreds, if not thousands, depending on the extent of the damage.

However, don’t despair. If you’re willing to roll up your sleeves, repairing rust yourself is entirely achievable and can save you a significant amount of money. With the right tools, materials, and a bit of elbow grease, you can effectively stop rust in its tracks and extend the life of your vehicle. This guide will walk you through the process of how to do auto body repair rust, ensuring a thorough and lasting fix.

Save Money by DIY Rust Repair

You might be familiar with repairing minor car scratches, but rust damage is a more serious issue. Professional rust repair services can quickly become costly, especially if multiple panels are affected. By tackling the rust repair yourself, you can save a considerable amount of money on labor charges. The initial investment in tools and materials will pay off significantly compared to the hefty bill from a professional body shop.

Before we dive in, it’s important to understand the scope of DIY rust repair:

Addressing Surface Rust

This guide focuses on repairing surface rust – corrosion that affects the outer panels of your car and hasn’t eaten through the metal structure. If you’re dealing with severe structural rust, such as rotted-out floorboards, holes in the bodywork, or damage to chassis rails, it’s crucial to consult a professional and potentially a welder. Structural rust compromises the vehicle’s integrity and requires specialized repair techniques.

Paint Considerations

This guide will take you through the rust repair process up to the priming stage, preparing the area for paint. If you are comfortable painting, you can certainly proceed with applying color and clear coat yourself. Solid colors are generally easier to achieve a good match with aerosol cans, while metallic paints can be more challenging to blend seamlessly.

If you’re hesitant about painting, a practical approach is to complete all the preparation and priming work yourself and then have a professional body shop handle the painting and blending. Professional spray equipment is designed for an even and flawless finish that is difficult to replicate with off-the-shelf aerosol cans.

Step-by-Step Guide: How to Fix Rust Damage on Your Car

Modern vehicles are more resistant to rust than older models, but factors like coastal environments or road salt exposure can still lead to rust formation well before the car’s mechanical components wear out. Minor rust damage on non-structural parts is manageable to repair at home, and with careful work, you can achieve a finish that makes the damage virtually invisible.

While professional restoration often involves cutting out rusted sections and welding in new metal, for everyday car rust repair, using fiberglass epoxy and body filler is a more accessible and practical method.

Building upon guides on fixing car scratches, let’s address what to do when a scratch has progressed to rust. Rust often starts from minor paint chips caused by gravel or door dings. Regular car washing and inspections are crucial to catch these early signs of damage. Applying touch-up paint promptly can prevent rust from developing and save you significant repair work down the line.

Let’s get started with the step-by-step process of how to do auto body repair rust. First, gather the necessary tools and materials:

Tools and Materials You’ll Need:

• Angle grinder with flapper wheels: For efficient rust removal.
• Wire brush: For cleaning and removing loose rust particles.
• Fibreglass epoxy gel: To seal and strengthen the repaired area.
• Body filler: To smooth out imperfections and create a level surface.
• Various grades of sandpaper (80, 400, 600, 1000, 2000): For progressively smoother sanding.
• Sanding block: To ensure even sanding and prevent uneven surfaces.
• Primer: To prepare the surface for paint and improve paint adhesion.
• Base coat paint (matching your car’s color): For color application.
• 2k clear coat paint (aerosol can): For protection and a glossy finish.
• Masking materials (paper and tape): To protect surrounding areas from sanding and paint.
• Rubbing compound: For polishing and blending the repaired area with the surrounding paint.
• Mineral spirits or Wax and Grease Remover: For cleaning surfaces.
• Rags: For cleaning and applying products.
• Tack cloth: To remove dust particles before painting.

How to Remove and Repair Rust Damage on Your Car: Detailed Steps

1. Preparation and Cleaning:

   • Thoroughly clean the area around the rust with soap and water. Dry the area completely.
   • Use mineral spirits or a wax and grease remover to remove any wax, grease, or contaminants that could interfere with the repair process.
   • Mask off the surrounding area with masking paper and tape to protect it from grinder sparks and sanding dust.

2. Rust Removal:

   • Equip your angle grinder with a flapper wheel. Start grinding the rusted area, working outwards from the center of the rust spot.
   • Apply moderate pressure and keep the grinder moving to avoid overheating the metal and causing warping.
   • Grind until you have removed all visible rust and reached clean, shiny metal.
   • For hard-to-reach areas or corners, use a wire brush to remove any remaining loose rust particles.

3. Applying Fibreglass Epoxy:

   • Clean the ground metal surface again with mineral spirits and allow it to dry completely.
   • Mix the fibreglass epoxy gel according to the manufacturer’s instructions.
   • Apply a thin, even layer of fibreglass epoxy over the bare metal area using a disposable brush or applicator. Extend the epoxy slightly beyond the sanded area to ensure complete sealing.
   • Allow the epoxy to cure fully as per the product instructions. This will create a waterproof barrier and prevent future rust formation.

4. Body Filler Application:

   • Once the epoxy is cured, lightly sand the area with 80-grit sandpaper to create a key for the body filler to adhere to.
   • Mix the body filler and hardener according to the product instructions. Apply a thin layer of body filler over the epoxy, using a plastic spreader.
   • Apply the filler in thin layers, building up gradually to avoid air bubbles and shrinkage. Overlap the edges of the epoxy and feather the filler outwards onto the surrounding paint.
   • Allow each layer of filler to become firm before applying the next. Don’t let it fully harden, as it’s easier to shape when slightly pliable.

5. Shaping and Sanding the Body Filler:

   • Use a body filler shaping tool or a rasp to roughly shape the filler to match the contours of the surrounding panel.
   • Begin sanding with 80-grit sandpaper wrapped around a sanding block to level the filler and remove excess material.
   • Gradually move to finer grits of sandpaper (180, then 400) to refine the shape and smooth the surface. Use a sanding block at all times to maintain a flat and even surface.
   • Check for imperfections by running your hand over the area. Any unevenness will be felt. Apply another thin layer of body filler if needed to fill low spots, and repeat the sanding process.

6. Priming and Sanding Primer:

   • Once you are satisfied with the shape and smoothness, clean the area thoroughly with a tack cloth to remove all sanding dust.
   • Apply several thin coats of primer, following the manufacturer’s instructions for drying time between coats. Primer helps to create a uniform surface for paint adhesion and reveals any remaining imperfections in the filler work.
   • After the primer is fully dry, lightly wet sand with 600-grit sandpaper to smooth out any primer texture and prepare for paint application. Clean the area again with a tack cloth.

7. Painting and Clear Coating:

   • Apply several thin coats of your base coat paint, allowing each coat to dry slightly before applying the next. Follow the paint manufacturer’s instructions for application and drying times.
   • Once the base coat is dry, apply 2-3 coats of 2k clear coat for protection and shine, again following the manufacturer’s guidelines.

8. Finishing and Polishing:

   • Allow the clear coat to cure completely for the recommended time (usually 24-48 hours).
   • Lightly wet sand any imperfections or orange peel texture in the clear coat with 2000-grit sandpaper.
   • Use a rubbing compound and a polishing pad or microfiber cloth to polish the repaired area, blending it seamlessly with the surrounding paint. This will restore the shine and remove any sanding marks.
   • Clean the area and remove masking.

By following these steps on how to do auto body repair rust, you can effectively tackle surface rust damage at home, saving money and maintaining the appearance and longevity of your car. Remember to always prioritize safety and use appropriate protective gear when working with tools and chemicals.