Can You Put Undercoating on Rust?

Many cars come from the factory with undercoating. It protects the bottom of your vehicle from dried salt, rust, and debris that can accumulate and cause issues down the road. What if you have lost some of that protection to rust? Can you put undercoating over rust?

No, it is not appropriate that you put undercoating on rust because undercoating is mainly used to prevent rust and corrosion in metals. The best way to prevent rust from your car is through rustproofing. Undercoating with trapped rust will only allow the oxidation to continue. 

Undercoating can only help protect your car, truck, or van from rust and other damage that can be caused by dirt, grime, gravel, and salt. To work properly, your vehicle’s undercarriage must be clean and free of any existing rust.

If you ever plan to use undercoating on your car, you must get rid of the rust with all possible means. You can find out more about undercoating, the application, and the importance of using it on your car below.

What Does Undercoating Mean?

Undercoating refers to the process of using layers of protective film to a vehicle’s undercarriage to guard them from corrosion and rust.

What Does Undercoating Mean

Vehicle undercarriages are susceptible to rust because they are regularly exposed to road salt and harsh weather conditions.

Importance of Undercoating Your Car

Many cars undergo rust when exposed to salt, this has necessitated the need for undercoating. Here are some benefits of undercoating your vehicle :

Importance of Undercoating Your Car

  • Prevents rust and corrosion: Undercoating is very important when trying to prevent your vehicles from rust. While keeping your vehicle clean is ideal, it doesn’t prevent rust. Putting an extra layer to protect your car from rust is highly recommended.
  • Saves damaged area in cars from total rust: Even for careful drivers, rust and corrosion is inevitable. When your car carriages get rust, using undercoating can still save the day. When done appropriately, undercoating can do a good cleaning of accumulated rust and dirt on your car.
  • Helps lower your Car premium: If you want your vehicle to have a proactive service which tends to reduce your risks on car insurance. What this implies is that you will pay less on your premium. This is particularly true of countries prone to high level rust.
  • Improves overall car appearance: When your car is undercoated, it looks better physically than your average car. This is because an undercoated car covers all scratches, cracks, rust and nibs your car has.
  • Increased Resale Value: Undercoated cars have higher value than cars that aren’t coated. This is because many people cherish cars that have been undercoated because they believe it will last long and prevent rust.
  • Helps reduce noise: Car undercarriage usually makes noise, especially when it has corrosion and rusting problems. However, when you undercoat all car body parts, it makes less noise.
  • Helps reduce repair cost: Car rustproofing and undercoating helps you limit the cost you spend on your cars for repair. Since all parts have been coated, you will not spend much in damages.

What Are the Methods of Applying Undercoating to Prevent Rust?

Since undercoating can help prevent rust in cars, using the right methods while applying it is important. Here are some methods to apply undercoating :

What Are the Methods of Applying Undercoating to Prevent Rust

  • Spray-On: This is also known as ‘Rubberized’ Undercoating. It is a very popular means to undercoat your car while preventing rust. You can use a tar-like chemical which can be found in solvents and protectants to spray all the parts of the car. This substance is like a barrier to prevent salt, oxygen and water from accelerating rust in your car.
  • Electronic Rust Inhibitors: These are excellent and flexible solutions to end corrosion in metals. It’s a little complicated, but it is a great idea to use undercoating. Although it seems a bit odd using an electrical method, it works better than others.
  • Using Lanolin-based wax or grease: You can use a lanolin method to apply undercoating. It is a great rust prevention method which works effectively in preventing corrosion. Normally, lanolin coatings are good lubrication which works well with company equipment and heavy-duty metals which need a water repelling rust inhibitor.
  • Dripless Oil Spray: This undercoating option helps repel moisture and rust on hardened surfaces. These wax substances will help fight against the oxidation process. It requires holes where you can drill into the body of the car where the rusting-out process happens.

Alternative Rust-Preventing Methods Asides Undercoating

If you don’t undercoat your metal or car, there are some rust preventing methods like :

Alternative Rust-Preventing Methods Asides Undercoating

  • Alloy: Using alloys to prevent rust is a very good way to stop rust. However, note that alloys like stainless steels aren’t good for all projects, but many metals can be coated with alloy.
  • Using Oil: Another popular way to prevent rust and corrosion or at least slow them down is using oil to protect metal. Be careful though of oil surfaces because they might promote some health issues.
  • Dry Coating: There are a good deal of excellent rust protection products which you can use to form a protective barrier over metal parts and materials. They work particularly well on shortage and shipping metal applications.
  • Using Paints: If you can get hold of good paints (especially oil-based ones), they are ideal to slow down rusting and prevent water from reaching the irons. Paints act as a good barrier, especially for metals exposed to air.
  • Good Storage: When you store your cars, and other metals in a place with good humidity, it will prevent rust. You can use some desiccant chemicals in your storage to help prevent rust.
  • Galvanized: Using galvanized. Coats like zinc can slow down rusting in iron and steel. It is an effective method of protecting your metals from corrosion.
  • Bluing: This is a rust-removal solution which allows you to use a magnetite layer to protect your iron. You must apply this solution regularly till the metal turns blue or black.
  • Vapor Corrosion Inhibitors: VCI are chemical Compounds which can be infused into several metals to protect it from rust. They do this by emitting rust removing vapors, which can create a barrier on your metals.


Undercoating is usually carried out on cars which ply dirty and salty routes. So, Can you put undercoating on rust? No, you can’t put undercoating on rust, however you can use undercoating to prevent your car from rust and corrosion. There are numerous methods of applying undercoating on cars, they include spray-on, electronic Inhibitors and using lanolin wax.

Using undercoating to stop rust comes with many benefits which includes better Resale Value, better appearance and less repair costs.

Evan Cooper

Evan Cooper

Hi, I’m Evan Cooper, the founder and an editor of this site, Doesitrust. I’m a chemical engineer and working in a rust-eliminating paint manufacturing company. Besides this profession, I’m a researcher and blogger.

More Posts - Website

Leave a Comment