Rust on cars is nothing new and it happens to every vehicle eventually but sometimes when you are refinishing a vehicle you can introduce problems that cause immediate or early corrosion problems.

A relatively new problem that many technicians are dealing with is corrosion on aluminum parts. Many hybrids and high MPG vehicles are using aluminum for exterior skins and structural parts. Additionally most drive trains have been using aluminum for decades so if you are repairing parts of this type you need to understand how to prepare them and what paints are appropriate for refinishing.

Common Causes of Corrosion on Automotive Vehicles

The most common cause of corrosion is failure of the paint system. This can happen from impact or improper techniques during preparation.

All steel surfaces that have been sanded to bare metal must be either protected within 3 hours or treated prior to paint application. Self etching primers are not a replacement for proper surface treatment.

Contamination of the paint products can cause early failure.

Dust, oil or moisture on surfaces that are receiving paint will cause blistering and early failure.

If the part is corroded all rust must be removed prior to continuing with primer.

If the part is bare metal you should never touch it with your bare hand or the oils on your fingers will cause rust to form under the paint.

How to Prevent Corrosion when Refinishing a Vehicle

Treat all metals with proper rust preventative and wash primers.

Clean and dry the vehicle surface to remove contaminants before applying paint including primers.

If you are wet sanding primer the vehicle must be completely dry before continuing. This means blowing out all jams and joints with compressed air that has been filtered for oil.

Use metal prep on any bare metal that has been exposed to air longer then 3 hours or re-sand the surface.

Use of Rust Converter is not as good an option as completely removing rust. Do not rely on it for best performance.

Seal your weld seams with seam sealer from both sides of the weld.

If you are brazing or using flux core mig wire make sure you grind the surface and remove all of the flux.

How to Cure Corrosion Problems on Vehicles

If you find you have a rust problem you must sand to bare metal and start again.