Sign Maintenance Australia


Will metal signs rust outside?

Will Metal Signs Rust Outside?


When it comes to outdoor signage, durability is a crucial factor to consider. Metal signs are a popular choice due to their sturdiness and aesthetic appeal. However, one common concern that arises is whether metal signs will rust when exposed to the elements. In this article, we will delve into the factors that contribute to rusting and explore ways to prevent it from occurring. Will metal signs rust outside?

Understanding Rust

Rust is a natural chemical process that occurs when metal reacts with oxygen and moisture. When these elements combine, they form iron oxide, commonly known as rust. The primary culprits behind rust formation are water and air. Outdoor environments expose metal signs to varying degrees of humidity, rainfall, and temperature fluctuations, which accelerate the rusting process.

Types of Metals and Rusting

Not all metals are created equal when it comes to rusting. Some metals are more resistant to corrosion than others. Let’s take a look at the most common metals used for outdoor signage and how they fare against rust:

Will metal signs rust outside?
Will metal signs rust outside?

Aluminum: Aluminum is highly resistant to rust due to its ability to form a protective oxide layer on its surface. This oxide layer acts as a barrier, preventing further oxidation and corrosion. Therefore, aluminum signs are an excellent choice for outdoor use, as they can withstand harsh weather conditions without significant rusting.

Stainless Steel: Stainless steel is another popular choice for outdoor signage due to its exceptional rust resistance. The chromium content in stainless steel forms a protective layer, known as chromium oxide, which acts as a shield against corrosion. Stainless steel signs are highly durable and can withstand exposure to moisture and other environmental factors.

Galvanized Steel: Galvanized steel is steel that has been coated with a layer of zinc to protect it from rust. The zinc coating acts as a sacrificial barrier, corroding instead of the underlying steel. Galvanized steel signs offer good rust resistance and are commonly used in outdoor applications.

Factors Affecting Rusting

While some metals are naturally more resistant to rust, certain environmental and maintenance factors can accelerate or mitigate the rusting process. Here are some key factors to consider:

Exposure to Moisture: Moisture is a significant contributor to rust formation. If a metal sign is constantly exposed to rain, snow, or high humidity levels, the risk of rusting increases. Regularly drying the sign and ensuring proper drainage can help prevent excessive moisture buildup.

metal signs rust outside

Saltwater and Coastal Environments: Saltwater and coastal areas are particularly challenging environments for metal signs due to the corrosive nature of salt. The salt in the air and water can accelerate the rusting process. In such locations, it is essential to choose highly corrosion-resistant metals like aluminum or stainless steel and regularly rinse the sign with fresh water to remove salt deposits. For sign maintenance outdoor sign protection see here.

Scratches and Damage: Any scratches or damage to the protective coating of a metal sign can expose the underlying metal to moisture and air, increasing the likelihood of rust formation. Regular inspections and prompt repairs are necessary to maintain the sign’s integrity and prevent rust from taking hold.

Preventing Rust on Metal Signs

While it may be impossible to completely eliminate the risk of rusting, there are several preventive measures you can take to extend the lifespan of your metal signs:

Use Corrosion-Resistant Metals

Selecting the right metal for your outdoor sign is crucial. Opt for metals such as aluminum, stainless steel, or galvanized steel that offer excellent rust resistance. These materials are specifically designed to withstand outdoor conditions and provide long-lasting durability.

Protective Coatings

Applying protective coatingssuch as paints, sealants, or powder coatings can provide an additional layer of protection against rust. These coatings act as a barrier, shielding the metal from direct exposure to moisture and oxygen. Regularly inspect the coating for any signs of wear or damage and reapply as necessary to maintain its effectiveness.

Maintenance and Cleaning

Regular maintenance and cleaning are essential to prevent rust formation on metal signs. Here are some maintenance tips to keep in mind:

Clean the signs regularly with mild soap and water to remove dirt, debris, and pollutants that can contribute to rusting.
Avoid using abrasive cleaners or tools that could scratch the protective coating.
Inspect the signs for any signs of damage, scratches, or peeling of the protective coating. Promptly repair or touch up these areas to prevent moisture from reaching the metal surface.
Consider applying a wax or protective sealant after cleaning to provide an additional layer of protection.

Proper Installation

The way a metal sign is installed can also impact its susceptibility to rusting. Ensure that the sign is properly mounted, allowing for proper drainage and ventilation. Avoid trapping moisture between the sign and the mounting surface, as this can create a favorable environment for rust formation.


Metal signs can withstand outdoor conditions and provide long-lasting durability if appropriate measures are taken to prevent rust. Choosing corrosion-resistant metals, applying protective coatings, regular maintenance, and proper installation are key to minimizing the risk of rust formation. By following these guidelines, you can enjoy the benefits of metal signs without having to worry about rust compromising their appearance and functionality. Remember, proactive care and maintenance are essential to ensure the longevity of your outdoor metal signs.

Leave a Reply

Your email address will not be published. Required fields are marked *