How does rust occur on tools, bicycles or cars?

Chemistry explained

How does rust form? Insight into the oxidation process

If you discover rust on your tools, bicycle or car, you should act quickly. But how does the damage actually occur? We clarify.

Anyone who has paid attention in chemistry class knows that some metals can rust, while others, such as gold and silver, are not reactive at all. But they also do not contain iron, which can quickly develop rust when it comes into contact with two certain elements. We explain what they are and how you can prevent rust.

While some materials such as stainless steel simply do not rust, surfaces made of iron or less noble types of steel react with the substances in their surroundings. The oxygen and moisture from the air cause iron to break down, creating a new chemical compound called iron oxide.

This appears yellowish to red-brown as rust. Since rust is porous and spreads quickly as moisture and oxygen penetrate, you should act quickly.

The smaller the rust stain, the better chance you have of removing it with home remedies such as baking soda and fluoride toothpaste or with chemical rust remover. Larger areas may need to be sanded before the rust spreads to the point where it eats holes in your iron or steel item.

To prevent iron items from rusting in the first place, you must shield the material from oxygen and water. You can do this with so-called corrosion protection agents. These can be varnishes or oils that you apply to the metal as a protective layer.

It also helps to clean the metal object regularly and keep it away not only from water, but also from more aggressive substances such as salt water or acids. These damage the upper layer of the metal and make it vulnerable to other elements, which cause so-called oxidation, i.e. the reaction with oxygen and water.

Salts in particular increase the conductivity of iron particles, which is why rust can spread even faster. This is particularly evident in regions such as near the Baltic Sea, where the air is particularly salty. How dangerous rust can be in the city was demonstrated in Frankfurt. Here a bridge had to be closed due to rust because safe operation was no longer possible.