Common Signs of Rust And What Causes Them

Posted on July 8, 2019 in Auto Repair, Tips From The Pros

If your car has it, you’re probably not happy about it. When left untreated a rust spot can quickly grow to cause major structural problems. In many states, a car with rust holes in the body won’t even pass inspection, regardless where the spots are located or how small they are. Tha's why it’s best to deal with the problem as soon as you spot it. Understanding the rusting process, the chronically problematic areas, and the ways to address trouble are crucial to repairing rust before it’s a serious issue. In this first article, we’ll discuss the types of rust and what causes them.

What Is Rust

Rust is the layman's term "oxidation," or the breakdown of iron-based metals. Given enough time and exposure to the elements, most types of iron and steel will completely reduce to iron oxide through the rusting process. Unfortunately, oxidizing metals are the most commonly used in cars. There are three main types of rust for drivers to be concerned about.

Surface Rust

The first signs of surface rust usually appear in the paint. This type of rust preys on small nicks, cracks, and scratches. As the clear coat wears you paint also becomes vulnerable to wear and abrasions. Once water penetrates the unprotected metal, it oxidizes. Pure iron and aluminum don't oxidize as aggressively but steal tends to have impurities in the metal that accelerate the rusting process.

Scale Rust

Exposed steel rusts at different rates depending on a few variables: alloy components, thickness, the environment the steel is in, and the type of heat treating the steel undergoes. Scale refers to the oxides of iron that are formed on wrought, or worked, metals as a result of mill operations (usually from high temperature rolling or furnace treatment). These chemical processes corrupt the surface and reduce the metal’s strength, making it more vulnerable to oxidation. Over time, water can react to the chemicals used in a heat treatment creating scale rust. Scale rust is usually hard but brittle and flaky.

Penetrating Rust

After prolonged exposure to the elements, oxidized steel is typically converted to brittle iron oxide and holes form. Automakers do a lot to try to prevent this severe type of corrosion, and many vehicles now have a thick coating on the underside which chemically seals the steel against oxidizing agents. But those dips and coatings wear off over time, especially on the road side of the vehicle where salt and other elements cause excessive wear on the metal. Penetrating rust can usually be prevented if it’s caught and treated early enough.

At V&F

Just a little extra vigilance reduces rust to no more of a problem than any other regular maintenance issue. At V&F, our expert mechanics use latest diagnostic equipment, and high-quality CARQUEST auto parts, to make sure we get the job done right. Call us today at (413) 314-2280 or schedule an appointment online.