Surface Rust vs Deep Rust and How to Fix Them

Rust is an extremely common problem for auto enthusiasts. There are two main types of rust: surface rust and deep rust. Both can potentially damage your vehicle. While both look similar at first glance, they have vastly different implications for the structural integrity of your vehicle.

Surface rust refers to the initial oxidation process that creates discoloration in the metal. Surface rust is manageable to fix with the right tools and technique. It only requires chipping away the rusted area and protecting the bare metal with a coating before repainting the surface.

Deep rust, or rot, is a more serious issue. Rot compromises the structural integrity of the rusted area. Rot repair requires cutting out the rotten section and welding in a patch panel before performing bodywork. This process can be quite labor-intensive and time-consuming. It's important to recognize the difference between rust and rot so you know what problem you're dealing with and how to address it effectively.

Surface Rust vs Deep Rust

Surface rust is usually the result of the metal being exposed to moisture or air. This causes the outer layer of the metal to corrode. While it may look unsightly, surface rust is typically easy to remove with a wire brush or sandpaper. Once the rust has been removed, the metal can be treated with a rust converter, which chemically converts the rust to a stable compound that can be painted over. With surface rust, it's important to spend time prepping the surface and not leave the raw metal exposed overnight as it could lead to more rust and corrosion.

Deep rot, on the other hand, is a much more serious issue. It occurs when the rust has penetrated deeply into the metal. Deep rot weakens the metal and can compromise the structural integrity of a vehicle. It's often the result of the metal being exposed to moisture over an extended period of time. For example, a car left in an area where water accumulates and pools is susceptible to deep rot.

To illustrate the difference, let's take a look at the bed of a Chevy C10. The area with deep rust has a lot of holes and the metal is soft, making it easy for a screwdriver to go through when pressure is applied.

In contrast, the area with surface rust is stronger and can still be saved by removing the rust, applying a coating, and painting it. The interior structure of the metal in the area with surface rust has not been compromised, so applying pressure to the area with a screwdriver does not puncture it.

In cases of deep rot, the affected area of the metal must be cut out and replaced with a patch panel. This requires welding skills and a level of expertise that many classic truck owners may not possess. Deep rot can be difficult to detect as it often begins on the inside of the metal and may not be visible until it has already caused significant damage.

Surface rust is typically easy to remove and does not pose a significant threat to the structural integrity of your classic truck, but deep rot is a much more serious issue that requires immediate attention. It is essential to inspect your vehicle regularly for signs of rust and to address any issues as soon as they are detected. Knowing the difference between surface rust and deep rust will help you to properly address oxidation damage and ensure the longevity of your vehicle.

What Causes Rust?

Rust is caused by a natural process known as oxidation. When iron or steel is exposed to oxygen and moisture, a chemical reaction occurs that causes the metal to deteriorate. This reaction causes the metal to become brittle and weak over time, leading to the formation of rust.

Moisture is one of the key factors that contribute to rust formation. Rain, snow, and other forms of precipitation can expose metal surfaces to moisture, which creates an ideal environment for rust to form. Even humidity in the air can be enough to cause rust to form on metal surfaces over time.

Salt exposure is another factor that contributes to rust formation. This is particularly common in areas where roads are treated in the winter to prevent ice buildup. Salt can cause corrosion on metal surfaces, leading to additional rust formation.

Other contributors to rust formation include exposure to acids, chemicals, and other corrosive substances. Industrial environments, for example, can be particularly harsh on metal surfaces and can lead to rust formation.

The final ingredient for rust formation is time. Since rust is a chemical reaction, there are many ways to delay and prevent the reaction from taking place, but even the most durable metals can succumb to rust if given enough time. The older your vehicle is, the greater the risk of rust damage. Even if you don't notice any rust on an older vehicle, it's best to do a thorough inspection before it's too late and the hidden rust turns to rot.

It's important to take steps to protect metal surfaces from exposure to moisture, salt, and other corrosive substances in order to prevent rust formation. This includes applying protective coatings to metal surfaces, storing metal objects in dry environments, and keeping them away from sources of moisture and other corrosive substances. By taking these steps, it's possible to prevent rust formation and keep the metal sections of your vehicle in good condition for years to come.

How to Treat Surface Rust vs Deep Rust

Treatments for surface and deep rust use different approaches, tools, and methods.

Surface rust removal usually involves scrubbing away the rust with a wire brush or sandpaper and then applying a rust converter or rust inhibitor. This process converts the rust into a stable material. Once the rust has been treated, the surface can be primed and painted to prevent further rust formation.

Treating deep rust or rot is a more complex and challenging process. The affected area will need to be cut out and replaced with a new piece of metal. This requires welding, which can be a difficult skill to master. If you are not confident with welding, it's recommended to seek help from a professional.

Full panel replacements are available for many vehicles if you're not comfortable with welding in a patch panel. Be sure to check out our panel replacement options at the bottom of this section.

Treating deep rust or rot will also require some bodywork. Once the new metal has been welded in place, the surface will need to be smoothed and shaped to match the surrounding area. This can be a time-consuming and labor-intensive process.

One of the most critical factors in treating rust and rot is addressing the underlying cause. If the rust or rot is caused by exposure to moisture, it's essential to identify and fix the source of the water or moisture. This could be anything from a leaky roof to a damaged window seal. If the moisture source is not addressed, the rust or rot will likely continue to spread, despite your efforts to treat it.

Restore Your Rusted Vehicle

Both forms of rust can cause aesthetic or structural problems for your vehicle. While surface rust is relatively easy to remove and does not cause significant damage on its own, it can eventually become deep rust.

Deep rust is much more difficult to deal with, as it can penetrate the metal's surface and cause severe structural damage, leading to costly repairs or replacements. It is essential to address rust as soon as you notice it to prevent the spread and mitigate further damage. Regular maintenance and proper storage can help prevent rust from forming, and timely treatment can extend the lifespan of your vehicle.