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What Is Undercoating And Why You Should Get It

Publish Date: Oct 22, 2016 Author: Robert Anzit & Bill Tucker Category: Reference

Protecting What You Can't See. Your RVs Unsung Hero!

About Undercoating & It's Benefits

Rusted out RV van body

What Undercoating Does

Undercoating provides an extra layer of protection to the underside of your recreational vehicle.  This area comes in contact with, and absorbs most of the moisture, salt, and other substances while parked and especially as you drive.

How Undercoating Works

It adheres to metals, even painted, to form an airtight barrier to combat heat, stress, and condensation, building on any factory coatings.  Undercoating protects against corrosion (rust) by preventing moisture from coming in contact with the metal.  Good products also reduce road and engine noise for a quieter ride.

Undercoating History

Did you know early undercoating products were made from chicken fat?! This process was a flop because the high sulfur content made it very corrosive.

Teaspoon of chicken fatHand wearing a glove dipped in tar

Tar and tar-like compounds were a vast improvement and were used for many years, beginning around the 1950's, but they did little to prevent bodies from rusting through. As the undercoating dried, chipped and broke away in chunks, water would get trapped between the remaining coating actually accelerating and promoting corrosion.

Undercoating Today

Undercoating products today contain a range of ingredients including fiberglass, rubber, ceramics, silicone, asphalt, or petroleum. These products offer different benefits but all protect against damage and the elements.

How Long Does Undercoating Last?

The length of time undercoating remains effective is dependent on the environment it is exposed and the use of the RV. Undercoating on a parked trailer for example may last years. A motorhome or trailer seeing a lot of road travel may require reapplication sooner due to impacts against the frame potentially chipping away at the coating.

Undercoating should still be visually inspected annually to ensure integrity.

Differences From Rust Proof

Rust proofing is generally a grease, wax or oil, but offers no real benefit against heat, impact or reducing road noise. Where rust proofing shines is it's ability to reach small spaces. Visible areas are sprayed and holes drilled in a vehicle so the oil can be sprayed inside to reach all areas.

  • Drip Oil Spray: Because of it's watery viscosity, drip oil sprays can reach most areas of a vehicle offering the best protection, however can be messy, dripping for days afterward, potentially leaving stains beneath.
  • Dripless Oil Spray: Dripless rust proofing uses a thick wax-like spray which is cleaner, avoiding any dripping afterward, but can't penetrate as well as a drip oil spray.

Rust proofing should be reapplied annually.

Why Undercoat Your RV

RVs benefit from undercoating more then rust proofing in part due to their construction. Where automobiles have sealed areas and tubular frames, recreational vehicles are built on top of an open rolling-chassis or trailer frame. This frame is almost entirely accessible and able to have undercoating applied to all exposed areas. Since undercoating also provides protection against heat, stress, noise and condensation while not requiring reapplication annually, it becomes an easy choice for a recreational vehicle.

Undercoating spray applicator

This article was originally published November 10th, 2014

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