To understand whether metal rusts without water, you need to know a little chemistry. Metal, or any substance for that matter, undergoes a chemical reaction when it comes in contact with an oxygen-containing compound. If there is no oxygen or water nearby, metal will not rust. So, does metal rust without water?
Yes, metal can rust in the absence of water. Some metals rust without water, and it is possible to have corrosion without any moisture present. Air has a small moisture content that can cause oxidation reactions in the metal itself.
Also, metal rusts whether it comes into contact with water or not because some metals are unstable when exposed to air.
Iron, for example, reacts with oxygen in the atmosphere to form iron oxide and will begin to rust if you leave it outside for long enough. Depending on environmental factors like temperature and humidity, even stainless steel can develop a rust film on the surface.
As you read further, you will understand how a metal rusts and how fast it can rust without water. You will also see how long it takes metal to rust, what saltwater does to metal, and how to stop metal from rusting.
Contents
How Does Rust Occur in Metals?
Rust occurs in ferrous metals (metals containing iron) when their iron components oxidize.
This oxidation takes place when water or moist air, oxygen, and the iron components of the metal meet, instigating a chemical process that leads to electron exchange which turns iron to iron oxide also known as rust.
How Fast Can A Metal Rust Without Water?
A metal will start rusting immediately it gets exposed to moisture and oxygen, but how fast it will rust depends on the following:
- Level of moisture and oxygen available.
- How much of the metal is exposed.
- Whether the metal has any protective coating on its surface.
Even though the oxidation reaction that causes corrosion on metals happens immediately, it might take some time before you notice it because visible rust signs may take a week or two before it becomes noticeable by the eyes.
The rust will start on the exterior of the metal first before it slowly penetrates through it, till all the iron components of the metal get oxidized and the metal rendered useless.
But you might be lucky to depict the rust signs on time because the oxidation process takes time to complete. When you see the signs, you can fix them with a good rust remover or cleaning agent meant for rust removal purposes.
Does All Metal Rust Without Water?
Metals rust without water, especially metals that contain iron because moisture can also act in place of liquid water to form rust. This rust occurs when the surface of the metal comes in contact with atmospheric moisture and oxygen, making the iron present in the metal oxidize and form iron III oxide.
The water molecules in the moisture break the bonds holding the iron molecules together and form the orange-red discoloration always seen on metals which are compounds of oxide.
If this reaction is not prevented or stopped, it will continue to go deep into the interior parts of the metal until it weakens the entire metal and disintegrates it.
How Long Will It Take A Metal To Rust Without Water?
Rusting of metal without water depends on the environment; in an outdoor environment, metal will rust within two to four days. In an environment with low humidity, it might take longer than two to four days, while in a high humidity environment, the period might be shorter than four days.
Can Saltwater Rust a Metal?
Metal will rust faster in saltwater than in freshwater because of the presence of salt which acts as a catalyst, speeding up the metal corrosion process.
Salt is a good electrolyte that adds ions to water, and this is why bridges and other metal structures built in oceans, seas, or water bodies that contain salt are always prone to corrosion unless their surfaces are coated with a protective layer to avoid rust.
Can Rust Be Prevented By Keeping A Metal Dry?
Yes, metal rusting can be prevented by keeping a metal dry. As stated before, metal will start to rust when it is exposed to water and oxygen. If you leave a metal exposed to water for a long time, it will start to corrode and develop rust.
How to Stop Rust?
When professionals who use metals for their job select alloys to be used for their construction projects, they usually predict how the metal will interact with the environment where it will be used. A metal’s corrosive rate can be used to check if a particular metal is suitable for a particular environment.
To prevent rust, you can use rust inhibitors to prevent a corrosive metal from reacting with moisture and oxygen in the environment, rust inhibitors like zinc phosphate. Also, metals used for industrial purposes can be galvanized, and this can be done by coating the metal with rust-resistant zinc, or titanium.
Other metals like copper, aluminum, bronze, and brass do not contain enough iron to make metal rust, so they can also be used to coat metals to prevent rusting.
But note that these listed metals can lead to the formation of patina on the metal’s surface, although the patina will not make the metal start corroding.
Frequently Asked Question (FAQ’s)
Can Pure Water Rust Metals?
No, when metals with iron components are exposed to ONLY pure water, they will not rust because pure water does not contain the necessary things that can make metal rust.
Can Saltwater Speed Up Oxidation?
In industrial and urban areas of coastal regions, acid rain and saltwater are well-known oxidation enhancers. The excessive presence of salt in these areas greatly increases the rate of rusting on metals.
Will Rusting Stop If A Metal is Kept Dry?
Rust will not spread quickly if all the parts of the metal are not wet. If one part of the metal is exposed to water, oxygen, and other conditions necessary for rusting to occur, and one part is dry without a single presence of water, the protected part might rust but not at the same pace as the part which is wet.
Final Words
Even if liquid water is not present, a metal will still rust once there’s an availability of moisture, and this moisture can be found freely in the air in any environment.
