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10 FAQs' - Frequently Asked Question about Rust Treatment for Classic Cars

Updated: Sep 5, 2023



Rust treatment for a classic car chassis and undersides is a crucial part of preserving and maintaining the vehicle's structural integrity. Here's a step-by-step guide on how to rust treat a classic car chassis and undersides: Materials You'll Need:

  1. Safety equipment (gloves, safety glasses, respirator)

  2. Wire brush or wire wheel attachment for a drill

  3. Rust converter or rust remover

  4. Rust inhibiting primer

  5. Chassis paint or undercoating

  6. Paintbrushes and/or spray gun

  7. Paint thinner (if using a spray gun)

  8. Sandpaper (various grits)

  9. Rags or paper towels

  10. Masking tape and plastic sheeting (optional)



Step-by-Step Process:

  1. Safety First: Always wear appropriate safety gear, including gloves, safety glasses, and a respirator, to protect yourself from rust particles and fumes.

  2. Inspect and Clean: Inspect the chassis and undersides of your classic car for rust and corrosion. Remove any loose or flaking rust with a wire brush or wire wheel attachment on a drill. Clean the surface as thoroughly as possible.

  3. Rust Converter: Apply a rust converter or rust remover according to the manufacturer's instructions. These products chemically convert rust into a stable surface that can be painted. Allow it to dry for the recommended time.

  4. Sand and Smooth: After the rust converter has dried, use sandpaper to smooth the surface and remove any remaining rough spots. Start with a coarse grit (around 80 or 120) and work your way to a finer grit (400 or 600) for a smoother finish.

  5. Clean Again: Wipe down the chassis and undersides with a clean, lint-free cloth to remove dust and debris from sanding.

  6. Primer: Apply a rust inhibiting primer to the treated areas. Use a paintbrush or a spray gun for even coverage. Allow the primer to dry thoroughly, following the manufacturer's instructions.

  7. Topcoat: After the primer has dried, apply a chassis paint or undercoating. You can choose a color that matches your car's chassis or go with a traditional black. Apply multiple thin coats for better coverage and durability, allowing each coat to dry before applying the next. A spray gun can provide a smoother finish, but brushes work well for smaller areas.

  8. Optional Masking: If you want to protect other parts of the car from overspray, use masking tape and plastic sheeting to cover them before applying the topcoat.

  9. Final Inspection: Inspect the treated areas for any missed spots or imperfections. Touch up as necessary.

  10. Reassemble: Once the paint has dried completely, reassemble any components you removed during the process.

  11. Regular Maintenance: To prevent future rust, it's important to regularly inspect the chassis and undersides for any signs of corrosion and address them promptly.


Rust treatment is a labor-intensive process, and the quality of the result depends on thoroughness and attention to detail. If you're not comfortable doing this yourself, consider seeking professional help from a body shop or restoration specialist experienced in classic cars. Proper rust treatment will help extend the life of your classic car and maintain its value.


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