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April 6, 2023
Can I Apply Paint to a Rusty Surface?
Written by: Sam Steele
All metal, particularly ships and other marina assets, gates, fences, bridges, and cell towers, eventually succumb to rust. It's all too easy to look at a rusted metal item and think that it can be salvaged with a few simple brush strokes. It’s important to understand that rust is much more than something that makes metal look bad. It is the result of a chemical reaction happening within the metal itself and breaking it down. For this reason, a simple paint job won’t solve the underlying issue. Let’s take a look at this concept a bit deeper.
Can You Paint Over Rust to Make it Go Away?
Painting over rust can jeopardize the metal surface's structural integrity and cause the paint to flake or peel off. Rust is a sign of corrosion, which can weaken and deteriorate metal surfaces over time. Painting over rust does not address the root problem—it just covers it up. Instead, it exacerbates the situation over time.
Think of rust on your commercial fishing boat like a cavity eating away at your teeth. What would happen if you don’t properly address the problem, opting for a teeth whitening treatment when you needed a root canal? Does that mean your dental problems are fixed? Far from it!
Paint Doesn’t Stop the Spread
One of the primary reasons painting over rust is problematic is that the rust will continue to spread under the paint. Rusting results from a chemical reaction between metal, oxygen, and moisture, which we will explain further in the next section. Painting over rust does not halt this process. It can, instead, actually trap moisture and oxygen beneath the paint, hastening rust formation!
Paint Flakes Off Rusty Surfaces
Another issue with painting over rust is that the paint may not adhere adequately to the surface. Rust creates a rough, uneven surface that does not provide a suitable base for the paint to adhere to, resulting in flaking or peeling paint over time. This leaves the metal surface exposed to further corrosion and rusting.
Rust Can Bleed Through Paint Colors
It's also worth noting that reddish-brown rust can bleed through paint, particularly lighter colors. Loose rust must be removed from the metal surface before applying paint to a rusted metal structure. A wire brush can be used to remove as much rust as possible to create a smooth surface. After the surface has been properly prepared, paint can then be added to the surface to enhance the look of the metal structure.
Paint Can Complicate Repairs
Furthermore, painting over rust can make repairing the metal surface more challenging in the future. If rust persists under the paint, the paint must be removed before repairing the rusted metal surface. This is a time-consuming and expensive process and may require the metal surface's complete replacement in severe cases.
Understand a Little More About Metal and Rust
Oxygen, water, and iron are required for oxidation—the process that creates rust. This reaction occurs when metal comes into contact with oxygen and moisture. Home care expert Bob Vila reminds us that any metal made of iron or alloys containing iron, such as steel, will rust with enough exposure to oxygen and moisture. Oxygen reacts with the metal atoms to create metal oxides, which are the rust that you see on the surface of the metal.
The formation of rust occurs due to the presence of water or moisture, which produces an electrolyte allowing electrons to flow between the metal and oxygen. This electrochemical reaction leads to the development of rust on the metal surface. You can read all about it in our blog Rust Eats Metal...and Budgets.
To avoid rust formation, a protective layer, such as a cold galvanizing compound, should be applied to metal surfaces. This will prevent contact between oxygen and moisture. As they say, “An ounce of prevention is worth a pound of cure!”
How ZRC Cold Galvanizing Compounds Work
Painting over rust is not recommended because it can harm the metal surface's structural integrity and cause the paint to flake or peel off over time. To guarantee a durable paint job and optimal surface protection, it's essential to address the rust before painting and then use a cold galvanizing compound rather than traditional paint.
Cold galvanizing compounds are coatings utilized to create a protective barrier against rust and corrosion on metal surfaces. They are an alternative to hot-dip galvanizing, which involves dipping metal in molten zinc to create a long-term protective coating against corrosion. These compounds contain zinc particles that are suspended in a liquid carrier, in this case paint. When applied to a metal surface, the zinc particles adhere to the surface and form a protective layer that acts as a “sacrificial anode.”
A sacrificial anode is a metal that is more reactive than the metal it is protecting. In the case of cold galvanizing compounds, the zinc takes on this role and corrodes instead of the metal surface of your gate, bridge, or other metal structure. When these zinc particles corrode, they create a passive layer on the surface of the metal which prevents further corrosion and protects your steel from corrosion.
It is a reliable solution to safeguarding metal surfaces from rust and corrosion. The main advantage of using cold galvanizing compounds is that they can be applied in the field, using only an aerosol can or paint brush. No special equipment is needed. This makes ZRC an affordable and convenient option for protecting metal surfaces.
ZRC Cold Galvanizing Compounds are commonly used in harsh outdoor environments where metal surfaces are exposed to saltwater, humidity, and extreme temperatures. They are effective everywhere though, and are known to protect against corrosion for years to come.
Order ZRC for Your Rust Prevention Needs
If left untouched, metal will eventually corrode. If your metal is rusty, you’re right to be concerned and want to do something about it. Before you can apply new paint, you must first remove all loose and flaking rust pieces using a sturdy metal brush. As long as you properly prep the rusted metal surface before painting with ZRC, it’ll stop further rusting and protect the metal surface for years to come.
To make it straightforward for you to find the right ZRC cold galvanizing compound, we have a Product Finder on our website. It's incredibly simple to use. Simply enter a few details, like the type of surface, desired color, and any application environmental factors. Our software will automatically connect you with the right ZRC product to meet your needs.
If you have any additional questions, we’re always here to answer them. Contact us via our website and our experts will lend support on a variety of topics, including ordering support, product fit, and more.