Rust Repairs & Fabrication

Rust is the layman’s term “oxidation,” or the breakdown of iron-based metals. Given enough time and exposure to the elements, most types of iron and steel will completely reduce to iron oxide through the rusting process. Since these metals are commonly used in cars, there are three main types of rust for owners to be concerned about:

1. Surface Rust

The first signs of surface rust usually appear in the paint. This type of rust preys on small nicks, cracks, and scratches. As the paint ages, it becomes vulnerable to wear and abrasions. Once water penetrates the unprotected metal, it oxidises. Pure iron and aluminium don’t oxidise as aggressively but steel tends to have impurities in the metal that accelerate the rusting process.

2. Scale Rust

Scale rust occurs when you leave surface rust to continue the corrosion process until it pits the metal. Chemical reactions cause rust that begins to damage the metal of the body panel itself. Road salts and salt spray are notorious causes of premature rust in vehicles, especially in New Zealand coastal areas where we are surrounded by salt. These salts create a chemical reaction that speeds up the corrosion process. Eventually, scale rust will work its way through the surface of a body panel and affect the integrity of the metal itself.

3. Penetrating Rust

Penetrating rust is, as the name suggests, rust that creates holes in the metal. This type of rust is the most advanced stage. You will need to replace portions of, or entire, body panels to repair the damage that penetrating rust has caused. 

1. Surface rust

Surface rust only affects the top layer of your vehicle’s body panels. This rust appears in chips and scratches in the protective paint coating or can present itself as bubbles under the paint surface which have started on the surface of the steel panel under the paint finish.

There are a few options available for attending to this type of rust.

The small chips and scratches can be simply brush touched with a small artist brush using a rust killer, undercoat and then top coat. The touch-up area can then be carefully sanded flat and polished to a high gloss to match the surrounding paint finish.

If the panels have signs of surface bubbles in the top finish of the paint then the affected areas will require sanding or stripping back to bare steel. The steel surface will then need to be treated with a phosphoric acid based product. This product will kill the surface rust and also leave a phosphate film on the steel surface.

The next steps in the process would be to coat the bare steel with an epoxy two pack etch primer, two pack undercoat and then top coat paint finish.

2. Scale Rust

Scale rust can cause pits into the metal and this will create more than just surface damage. This will need more aggressive techniques to remove scale rust damage. Ignoring the problem will allow it to get worse until it eats through the metal completely. There are many ways of removing scale rust. The choice of method to use depends on the actual vehicle, the condition of the vehicle and where on the vehicle the scale rust is located.

The methods available to use are….. Grinding, Sanding, Media blasting, Dry sandblasting, Wet sandblasting and Acid dip stripping. In some cases, several of these options could be used on the same vehicle to remove scale rust. If the scale rust has developed further steel sections may need to be repaired or replaced.

The steel surface will then need to be treated with a phosphoric acid based product. This product will kill any remaining surface rust and also leave a phosphate film on the steel surface. The next steps in the process would be to coat the bare steel with an epoxy two pack etch primer, fill and finish surface ,two pack undercoat and then top coat paint finish.

3. Penetrating Rust     

Areas where the rust has penetrated deeply into the metal or has progressed further into rust holes, these areas will require cutting out and a new steel repair panel would need to be fabricated and welded in place. If it is more cost effective we would purchase a factory or aftermarket replacement repair panel to weld in place.

The steel surface will then need to be treated with a phosphoric acid based product. This product will kill any remaining surface rust and also leave a phosphate film on the steel surface.

The next steps in the process would be to coat the bare steel with an epoxy two pack etch primer, fill and finish surface ,two pack undercoat and then top coat paint finish.