Undercoating & Rust Proofing—What is the Difference?


Simply put, undercoating protects the frame of your vehicle and rustproofing protects the body of your vehicle. Below we are going to walk you through each of the procedures so you can get a clear idea of what the purpose of each service is. Many people ask us which is the best protection for the potential corrosion due to winter road salt application, and we always recommend undercoating for this type of protection. It gives a solid protective barrier against any salt deposits and will greatly increase the life of your vehicle’s frame.

rusty frame rail

Undercoating: WHY and HOW we do it.


To have your car or truck undercoated means having a layer of protection sprayed onto the undercarriage of your vehicle, including the floorboards, wheel wells, and frame. Since the underside of your vehicle is not washed during regular maintenance and is not even rinsed by regular rainwater, it is important to protect the exposed parts from rust and corrosion.


Applying an undercoating the very first thing that we're going to do is clean the whole underside of your vehicle - remove all the road grime, road salt, mud, grease - anything that contributes corrosion. Then we'll put the vehicle on our four-post drive on the lift, put it up in the air, and dry the underside of the vehicle with our high-pressure air system. Then we'll apply a thick coating of our abrasion-resistant undercoating to the underside of the vehicle, the floor pans, frame rails, rocker panels - everything on the underside of your vehicle that doesn't move or get hot (like your exhaust system, drive train or shocks).

Rust Proofing: WHY and HOW we do it.


Rust is a sneaky beast to deal with. We have all seen cars completely rusted out on the side of the road or abandoned in a ditch, and we can picture doors with huge holes rusted out with only a hint of original paint showing. The interesting thing is that rust actually starts to accumulate on a car very early in ownership, it is just hidden away inside the floor panels, inside the doors, and underneath the wheel wells so it is impossible to see. Once you start to see the first signs of rust, it has already been growing from the inside all along. When you realize where the rust starts, the solution is a no brainer.


To bake up a delicious batch of rust, you only three ingredients: Iron, water, and oxygen. Since we drive out in the elements all day in vehicles made of steel, we are creating the perfect environment for rust to form, grown, and eventually devour everything in its path.

Once you know how rust forms the solution is simple. The rust proofer we use is a type of extremely thick wax that can be sprayed onto surfaces or into tight spaces using a hose. By laying a thick durable wax coating inside the doors, the hood, and between the pinch welds of the frame we remove all three of the ingredients needed for rust to form. Oxygen can’t get to the iron ore in the steel and water and condensation are repelled away on contact.

We do not spray rust proofing on the underside of the vehicle. Since it is a waxy finish it makes an awful mess, dirt sticks to it, and your mechanic will be cursing your name if they need to get in there to repair something. Since the exposed areas of the vehicle are able to dry, unlike the inside of the panels, it is much less of a risk for rust.

If you'd like to protect your vehicle against corrosion - Undercoating and Rust Proofing are great options - reach out to Automotive Protection Services in Fairfax Virginia (703) 591 0900