What Are the Causes of Bubbling Paint on a Car?

Written by owen pearson | 13/05/2017
What Are the Causes of Bubbling Paint on a Car?
(vintage endurance race car image by Xavier MARCHANT from Fotolia.com)

A good automotive paint job is very difficult to achieve, especially if you decide to undertake the job yourself. There are a variety of problems that can make your paint job go awry, and can make your car look unsightly. One such common problem is bubbling paint. Understanding the causes of bubbling paint on a car will help you prevent this problem, so you can enjoy your car's new paint job for years to come.

Painting Over Rust

When metal comes in contact with water or water vapour, the process of rusting occurs. The water vapour mixes with oxygen to corrode and destroy the metal. If paint is applied over rust, no matter how small the rusted area, the oxidation process will release gases beneath the surface of the paint. Because the gases cannot escape, they form paint bubbles.

Improper Metal Treatment

Because rust is not always large enough to be visible, many people assume it does not exist. The metal should be treated with phosphoric acid to ensure that pinhole-sized iron oxide--active rust--is converted into iron phosphate. Allow up to 12 hours for the phosphoric acid to stop the oxidation process before applying paint. This will help prevent air bubbles from forming beneath the paint.

Insufficient Waxing

Waxing provides a sealant for your paint, so that moisture can't seep through microscopic holes in the paint's surface and cause the metal beneath to rust. To prevent rusting and paint bubbles, wax your car at least every three months.

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