Rust: What is it and How to Keep Your Materials Safe

by Joost Nusselder | Updated on:  June 13, 2022
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Rust is an iron oxide, usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Several forms of rust are distinguishable both visually and by spectroscopy, and form under different circumstances.

In this article, I’ll cover the basics of rust, including its causes and prevention.

What is rust

What the Flaky Coat? Understanding Rust and Its Causes

Rust is a term commonly used to describe the oxidation of iron or steel. Technically, rust is an iron oxide, specifically a hydrated iron(III) oxide that is formed when iron reacts with oxygen and water in the presence of air. This reaction is known as rusting and occurs when metal is exposed to air and moisture for a long period of time, resulting in the formation of a reddish-brown flaky coat.

How Does Rust Occur?

When iron or steel comes into contact with oxygen and water, a reaction occurs that results in the formation of iron oxide. This reaction is catalyzed by the presence of water or air moisture, which causes the metal to corrode and form hydrous iron(III) oxides and iron(III) oxide-hydroxide. Over time, the resulting flaky coat can spread and cause pitting or cavity formation in unprotected steels, reducing their strength.

Can Rust be Prevented?

While rust is an inevitable occurrence over the years, it can be easily prevented or treated through various methods, including:

  • Applying a protective coating to the metal surface to reduce exposure to air and moisture.
  • Regularly cleaning and drying metal surfaces to reduce the presence of deposits and humidity.
  • Avoiding confined spaces, crevices, and gaps where moisture can accumulate and cause rust to spread rapidly.
  • Using stainless steel or other rust-resistant metals in areas where rusting is a common problem.

What are the Effects of Rust?

Rust can have several effects on metal surfaces, including:

  • Reducing the strength and durability of the metal.
  • Creating narrow or deep pits that can spread rapidly and cause further damage.
  • Making the metal surface wider and more porous, which can lead to increased rusting.
  • Creating a crevice or gap that can trap moisture and cause rust to spread rapidly.
  • Contributing to the formation of pitting or cavity formation in unprotected steels.

Chemical Reactions: The Science Behind Rusting

Rusting is a chemical process that occurs when iron is exposed to air and moisture. The process of rusting is a result of a complex series of chemical reactions that involve the combination of iron, oxygen, and water molecules. The main chemical reaction that occurs during rusting is the oxidation of iron, which produces iron oxide.

The Role of Oxygen and Moisture

Oxygen and moisture are the key elements that cause rusting to occur. When iron is exposed to air, it combines with oxygen to form iron oxide. Water is also required for rusting to occur because it carries the oxygen and other compounds that are necessary for the chemical reaction to take place.

The Chemical Reaction of Rusting

The chemical reaction for rusting is: 4Fe + 3O2 → 2Fe2O3. This means that four atoms of iron combine with three molecules of oxygen to produce two molecules of iron oxide. The process of rusting begins when iron is oxidized to iron(II) ions by oxygen. The iron(II) ions then combine with water molecules to form iron hydroxide. This compound then oxidizes further to form iron oxide, which appears as the red-brown scale that we commonly associate with rust.

The Effects of Rusting on Metal

Rusting can have a number of negative effects on metal, including flaking, corrosion, and weakening of the structure. Rusting occurs when iron is exposed to air and moisture, and the resulting iron oxide is a weak and brittle material that can easily flake off. This can cause the metal to weaken and eventually fail. In the case of a bridge or other structure, rusting can be a serious safety concern.

Preventing Rusting

Preventing rusting requires removing the presence of moisture and oxygen. This can be done by keeping the metal dry and coating it with a protective layer, such as paint or oil. Another way to prevent rusting is by using a metal that is less likely to rust, such as stainless steel or pure iron.

The Importance of Understanding Rusting

Understanding the chemical reactions that occur during rusting is crucial for preventing and treating rust. Rusting is a complex process that involves the combination of several compounds and electrochemical reactions. By understanding the key elements and reactions involved in rusting, we can better prevent and treat rust in our everyday lives.

Why Rust is a Safety Hazard and How to Prevent It

Rust is not just a cosmetic issue, it can pose serious safety hazards in construction and tools. Here’s why:

  • Rust weakens the structural integrity of metal components, endangering regular users and passersby.
  • Tools with rusted parts can break or malfunction, causing serious injury or even death.
  • Rust can stain and ruin products, leading to financial losses for manufacturers and consumers alike.

The Health Risks of Rust

Rust is not just a physical hazard, it can also pose health risks due to the following reasons:

  • Rust can harbor bacteria, including tetanus, which can cause serious infections if it enters the body through a puncture wound, such as from a rusty nail.
  • Places with rust growth, such as outdoors or in damp environments, can be dangerous for people with respiratory issues as rust is an oxide substance that can be harmful when inhaled.

Preventing Rust and Ensuring Safety

To prevent rust and ensure safety, the following measures can be taken:

  • Regular inspection regimes should be in place to identify and address rust growth in construction and tools.
  • Legislation should be in place to ensure that manufacturers are held accountable for producing products that are safe and free from rust.
  • Using products that help prevent rust, such as rust inhibitors and coatings, can be effective in stopping rust growth.
  • Combination of chemical reaction, air and moisture are the main causes of rust, so keeping metal components dry and clean can help prevent rust.

Watch Out! These Materials Are Prone to Rusting

Steel is a mixture of iron and carbon, which makes it a popular choice for construction and manufacturing. However, steel is also one of the most significant rusting metals. Compared to other metals, steel rusts relatively quickly, especially when exposed to water and oxygen. Steelcast and ironwrought are two different types of steel that can rust.

Cast Iron: Not So Strong Against Rust

Cast iron is an alloy that contains iron, carbon, and trace amounts of other elements. It forms when molten iron is poured into a cast, hence the name. Cast iron is known for its resistance to wear and tear, but it is not so strong against rust. Cast iron objects can rust regularly, especially when exposed to water and oxygen.

Wrought Iron: Rusts Less Than Steel and Cast Iron

Wrought iron is a pure form of iron that contains very little carbon. It is known for its resistance to rust and corrosion, making it a popular choice for outdoor furniture and decorative objects. Wrought iron rusts less than steel and cast iron, but it still requires protection from water and oxygen.

Stainless Steel: A Shield Against Rust

Stainless steel is an alloy that contains iron, chromium, and trace amounts of other elements. The combination of these elements forms a protective layer that shields the metal from rust and corrosion. Stainless steel is nearly impervious to rust, making it a popular choice for kitchen appliances, medical equipment, and outdoor furniture.

How to Prevent Rust

Preventing rust requires applying a shield or protection to the metal. Here are some tips to prevent rust:

  • Regularly wipe dry any metal that is exposed to water.
  • Remove any rust spots by wiping them away with a mixture of water and vinegar.
  • Apply a coat of paint to the metal to shield it from water and oxygen.

Remember, only iron and alloys that contain iron can rust. So, if you want to avoid rust, choose metals like stainless steel or wrought iron.

Metals that Stay Shiny: A Guide to Materials that Don’t Rust

Rust is the bane of many metal objects, causing them to corrode and degrade over time. But did you know that there are metals that resist rust and corrosion? In this section, we’ll explore the properties of these metals and why they are able to stay shiny and new-looking even after years of use.

Metals that Don’t Rust

Here are some of the metals that are known for their resistance to rust and corrosion:

  • Stainless Steel: This type of steel contains chromium, which reacts with oxygen to form a protective layer on the surface of the metal. This layer shields the steel from further corrosion and helps it resist rust.
  • Aluminum: Like stainless steel, aluminum forms a protective oxide layer when exposed to air. This layer is thin and transparent, so it doesn’t affect the appearance of the metal. Aluminum is also lightweight and easy to work with, making it a popular choice for many applications.
  • Copper: Copper is a natural anti-corrosion metal that is often used in electrical wiring and plumbing. When exposed to air and water, copper forms a greenish patina that protects the metal from further corrosion.
  • Brass: Brass is a mixture of copper and zinc, and it is classified as a “yellow metal.” Brass is resistant to corrosion and tarnish, and it is often used in decorative objects and musical instruments.
  • Bronze: Bronze is a mixture of copper and other elements, such as tin, aluminum, or nickel. It is known for its durability and resistance to corrosion, and it is often used in statues, bells, and other objects that are exposed to the elements.
  • Gold and Platinum: These precious metals are highly resistant to corrosion and tarnish, making them ideal for jewelry and other decorative objects.

How Metals Resist Rust

So, what is it about these metals that allows them to resist rust and corrosion? Here are some of the factors that come into play:

  • Protective Layers: As we mentioned earlier, metals like stainless steel and aluminum form protective layers when exposed to air and water. These layers shield the metal from further corrosion and help it resist rust.
  • Lack of Iron: Rust is formed when iron reacts with oxygen and water to create iron oxide. Metals that contain little or no iron are therefore less likely to rust.
  • Chemical Reactivity: Some metals are simply less reactive than others, which means they are less likely to form chemical compounds that lead to rust and corrosion.
  • Combination of Elements: Some metals, like bronze, are able to resist rust because they are a combination of different elements. This mixture creates a metal that is more resistant to corrosion than any of its individual components.

Methods for Creating Rust-Resistant Objects

If you want to create objects that are resistant to rust and corrosion, here are some methods to consider:

  • Galvanizing: This process involves coating a metal object with a layer of zinc, which acts as a shield against rust and corrosion.
  • Weathering: Some metals, like copper and bronze, develop a protective patina over time when exposed to the elements. This patina acts as a shield against further corrosion.
  • Stainless Steel: As we mentioned earlier, stainless steel is highly resistant to rust and corrosion. Using stainless steel for objects that will be exposed to water or moisture is a quick and easy way to ensure they stay rust-free.
  • Regular Maintenance: Even metals that are resistant to rust and corrosion require some maintenance to stay in top condition. Keeping objects clean and dry, and storing them away from moisture, can help prolong their lifespan.

Ways to Keep Rust at Bay

One of the best ways to prevent rust is by storing metal products properly. Here are some tips to keep in mind:

  • Store metal parts or products in a low-moisture area or inside a temperature and humidity-controlled environment to slow down rust.
  • Utilize desiccant drying agents in storage to reduce moisture levels.
  • Regularly wipe down metal surfaces to remove any moisture that may have accumulated.
  • Store metal pieces in a dry cloth or wrap them in plastic to keep them dry.


Galvanizing is a process that coats iron or steel in zinc to protect it from rust. Zinc is highly resistant to corrosion, and when it combines with iron or steel, it creates a protective coating that prevents rust from forming. Galvanizing is an excellent method for preventing rust, especially for outdoor accessories or ferrous metals that are highly reactive to oxygen and water.

Regular Maintenance

Caring for metal products is crucial to prevent rust from forming. Here are some ways to reduce the risk of rust:

  • Scrape off any rust as soon as it appears to prevent it from spreading.
  • Keep metal surfaces dry and avoid contact with wet surfaces.
  • Use a high-quality rust-resistant coating or protective oxide layer to provide superior protection against rust.
  • Regularly inspect metal products for scratches, cracks, or other signs of damage that may hold moisture and cause rust to form.
  • Use stainless steel or other highly resistant metals to provide superior protection against rust.
  • Rolling metal products creates a smoother surface texture that traps and holds less moisture, reducing the risk of rust formation.

Other Prevention Methods

Here are some additional ways to prevent rust from forming:

  • Use different metals that are less reactive to oxygen and water, such as chromium or stainless steel.
  • Contain metal products in a dry environment to reduce the risk of moisture reaching the surface.
  • Use available rust prevention products, such as rust inhibitors or protective coatings, to provide an extra layer of protection against rust.
  • Keep metal products away from hot or cold surfaces that may cause condensation to form and increase the risk of rust formation.

Remember, prevention is key when it comes to rust. By taking the necessary steps to protect your metal products, you can ensure that they remain rust-free and in the best possible condition for years to come.

Treating Rust: The Best Way to Convert and Protect Your Metal

When it comes to treating rust, there are several types of converters available in the market. Here are the most common ones:

  • Acid-based converters: These types of converters chemically convert rust into an inert oxide. They contain phosphoric acid as the primary ingredient and are known for their fast reaction speed. Additionally, they lower the pH of the rust, which speeds up the reaction. Acid-based converters are best used on small rust spots and are available in aerosol or sprayable forms.
  • Tannic acid-based converters: These converters contain tannic or ferric acid, which chemically converts rust into a stable, reddish-brown layer. They are best used on larger rust spots and are available in quart or gallon sizes.
  • Organic polymer-based converters: These types of converters contain a special type of polymer that acts as a rust-inhibiting agent. They provide a hard, dry, and strong protective layer directly on the metal surface. Organic polymer-based converters are available in both aerosol and sprayable forms.

Improving Rust Protection with Paint

While rust converters offer a protective layer, adding paint can further improve the protection. Here are some things to keep in mind:

  • Use a high-quality paint that is specifically designed for metal surfaces.
  • Apply the paint after the converter has completely dried.
  • If repainting an old surface, make sure to peel off any loose paint and sand the surface before applying the converter and paint.


So, rust is a chemical reaction that occurs when iron comes into contact with oxygen and water. It’s a pretty common problem, but you can prevent it by treating your metal properly. So, don’t forget to keep your metal dry and clean! You’ll be fine. Thanks for reading!

I'm Joost Nusselder, the founder of Tools Doctor, content marketer, and dad. I love trying out new equipment, and together with my team I've been creating in-depth blog articles since 2016 to help loyal readers with tools & crafting tips.