Does Iron Rust Without Water?

Whether the presence of air and moisture determine iron rusts without water. Air without water or air with low humidity will prevent rust from occurring. Any iron product, such as iron nails, will certainly rust over time, allowed to contact both air and water. But of the truth, does iron rust without water?

Yes, iron can rust without water. This reaction is called dry oxidation. Dry oxidation is when oxygen reacts with the metal in the absence of any water.

When left exposed to the atmosphere, iron rusts without water, especially in a humid environment. It will rust without water because it acts as an oxidant, meaning that it pulls electrons from other elements and oxidizes them.

In this article, you will learn how rust occurs in iron, how long it takes iron to rust, the conditions that can accelerate the rate of iron rusting, and how to prevent it

How Rust Occur in Iron?

Iron, with all its malleability, lightweight, and strength is highly prone to rust in its natural state. No matter where it is kept, with time, it will form a hydrated iron III oxide which is usually known as rust.

Rust in iron comes about because of the oxidation reaction. This reaction occurs when the iron is exposed to oxygen and moisture or water, especially saltwater.

How Rust Occur in Iron

During this chemical reaction, iron will be converted to iron oxide which is the flaky, orange-brownish appearance that is normally seen on the surface of iron, and will progress to the entire piece of iron with time if not stopped.

When iron is exposed to either moisture or moist air and oxygen, oxidation reaction will start, converting the iron to hydrated iron oxide until the whole metal disintegrates.

How Long Will It Take An Iron To Rust?

If you have ever kept a piece of iron where rain will touch it before, you would have probably witnessed the speed at which the iron rusts. Iron is susceptible to rust and is more likely to start rusting after four to five days of exposure to oxygen and moisture.

Conditions That Speed Up Rate of Rusting in Iron

While it’s quite easy for some people to see signs of rust on iron after a few days of exposure, it might take others more days to see it. Some conditions can regularly skyrocket the rate at which iron will rust once they are available.

Speed Up Rate of Rusting in Iron

Some of these conditions are:

1. Grade of iron

Different grades of iron will rust at varying speeds. An iron that contains an alloy of metals that are more prone to rust will experience rusting more easily than those with an alloy of metals that have a very low corrosion potential.

2. Method of maintenance

The method used to maintain (clean, finish, etc) an iron also affects the rate at which it will rust. An iron that is regularly cleaned with vinegar, baking soda, and other related rust cleaning agents will see a slow formation of rust if it will form at all.

Also, rinsing and drying a piece of iron thoroughly before storage can also reduce the rate at which it will rust.

3. Atmospheric pressure and temperature

The temperature and atmospheric pressure of the environment where a piece of iron is kept also have an impact on the rate at which the iron will rust.

Iron kept in a place where there is a high level of heat will rust faster, especially if oxygen and moisture are also readily available.

How to Prevent Rust in Iron?

Rust is a progressive phenomenon, that if left unchecked or prevented, can damage an entire piece of iron, making it not serve the purpose why it was purchased.

How to Prevent Rust in Iron

To protect an iron from rust, the surface has to be separated from moisture and oxygen which are the main catalysts of oxidation. To do this effectively, some measures can be taken, and some of these measures are:

1. Galvanization

Galvanization is a common anti-rust process for iron. It’s a process where a protective coating is applied on the surface of iron. This coating is usually a zinc layer that acts as a barrier between the immediate environment and the piece of iron.

The result of this coating is that the iron will not have any contact with moisture, liquid saltwater, or oxygen. If this zinc coating doesn’t get scraped or scratched, the galvanized iron will not rust.

2. Painting

Painting is a simple process that can also protect a piece of iron from rusting. Like galvanization, painting a piece of iron will create a barrier and prevent it from reacting with oxygen and moisture in the immediate environment.

The only disadvantage of this rust prevention method is that it does not last long on the surface of the iron, the way other rust prevention techniques do.

3. Surface plating

Surface plating is another prevention method used on iron to prevent rust. In this method, chrome or nickel is being deposited on the surface of the iron. The nickel or chrome does not contain iron and is not prone to rust.

This process is very complex to accomplish, but it’s an effective way of preventing iron from rusting.

 Frequently Asked Questions (FAQ’s)

Can Dry Air Rust Iron?

For rust to occur, iron and oxygen will react to form iron oxide while releasing electrons at once. Iron kept in a place where there’s dry air will not rust easily most of the time. However, in humid regions, iron will rust faster because of the presence of moist air in those areas.

Can Acid Rain Rust Iron?

In regions and areas where there is acid rain or salty waters, the speed at which iron oxidation occurs is always high due to the electrochemical reaction potentials of salt present in those water bodies, and chemical components of acid rain.


Iron can readily rust without liquid water, all that is required is moist air and oxygen. The moist air will react with the iron to break down the oxygen molecules available in the air, and the electrochemical process will make rust start forming.

Evan Cooper

Evan Cooper

Hi, I’m Evan Cooper, the founder and an editor of this site, Doesitrust. I’m a chemical engineer and working in a rust-eliminating paint manufacturing company. Besides this profession, I’m a researcher and blogger.

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