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Why Do Cars Develop Rust?

September 01, 2020

info and services for hance auto body repair in dallas and plano

If you’re a car owner, you know the dread you feel when you notice a new rust spot, also known as iron oxide. Rotting metal is unsightly, to be sure, but it’s also dangerous for your vehicle in large quantities. Large patches of rust impact the structural integrity of your car, plus it can harm the car’s resale value.

First and foremost, be sure to get auto body repair after an accident. Leaving a large dent or scratch will welcome rust quickly.

Why do Cars Rust?

Iron oxide forms when an iron-containing metal, like steel, becomes exposed to oxygen and moisture for long periods of time. Auto bodies are made from steel because this material is durable, strong, readily available and moldable. Unfortunately, though, steel contains iron, meaning it’s susceptible to iron oxide.

Generally, newer vehicles are far less susceptible to rust than older vehicles. The paint used on those newer vehicles gives some level of protection, along with the use of galvanized steel, which — under the proper circumstances – can last up to 70 years without corroding. However, during manufacturing, galvanized steel is cut, bent, drilled, and heated, which compromises its structural integrity. This is why areas of your car comprised of this steel, such as panels and doors, are more likely to rust.

The primer and paint that manufacturers use on cars gives some level of protection from rust. However, if this coating is damaged in some way from dents or scratches, moisture makes its way in to the bare metal under the paint. Without the protective nature of this coating, your car will then begin to rust. This is why it’s so important to get scratches and dents fixed right away.


Location Matters

Rust needs an anode, cathode and electrolyte to start forming. The metal in your car gives it the anode and cathode, with water being the electrolyte. Ever wonder why rust is more likely to form in humid climates or by the ocean? That’s due to the high salt content of that humid ocean air.

Salt water is more effective at carrying electrons than water featuring a low salt content, which means it’s also more effective at eating away at parts of your car. The situation is worsened if you live in a cold climate where salt is used on roads to melt ice and snow.

Rustproofing Methods

Your best defense against iron oxide is rust proofing. You may decide it’s not worth the investment, though, and this will depend on your situation. If you reside in the desert, you don’t really need to. If you reside in a northern climate and want to hang onto your car for the long term, rustproofing is a good way to go. Because there are a few different methods available, you should always consult a trusted mechanic before making this investment.

  • Electronic Module: This is one of the newest rust protection methods available, but it’s also controversial. This is a small device that has to be installed in your vehicle, which emits a weak current throughout the vehicle’s body to prevent reactions with oxygen.
  • Tar-Based Spray: This first came out in the 1950s to ensure quieter car rides. These tar-based sprays, also known as undercoating, are an affordable and non-invasive rustproofing option.
  • Dripless Oil Spray: This is designed to protect your car’s underbody because it forms a moisture seal. In general, it covers more surface area than the tar-based spray.
  • Drip Oil Spray: Similar to a dripless spray, this has more leftover residue, and leads to dripping oil. It’s generally more effective than dripless, as the oil can access parts of your car that the dripless oil simply cannot.

Park Carefully

How and where you park your vehicle can determine whether or not rust will form. Park on a paved surface if possible, which exposes your vehicle to much less moisture than a surface that is covered by dirt, grass or snow. Apply sealant to cracked asphalt surfaces, which expose your car to unnecessary moisture.

Keep Your Vehicle Clean

Because your car’s paint acts as a moisture seal, it’s imperative that you take care of the paint job to maintain rust prevention. Wash your car at least once every two weeks, applying a wax coating once a month. Make sure you’re washing the underbody, as road salt and grime can collect underneath your vehicle.

Contact Hance’s Uptown Collision Center

To learn more about our autobody repair to prevent rust formation, contact us in Dallas at 214-214-4717.



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