The 10 Best Car Undercoating Paints to Buy 2021

The 10 Best Car Undercoating Paints to Buy 2021

Your car is one of the most valuable and most utilized investments that you can ever have in your life. Unfortunately, its underside regularly comes into contact with a wide variety of substances. It can get splashed with water, doused with chemicals, and hit by debris and dirt that you encounter on the road. This exposure can cause major rusting or corrosion on your vehicle, compromising its road-worthiness as well as your safety over time.

Undercoating your vehicle is an excellent way to guarantee that this isn’t going to happen. In this article, we present to you the ultimate guide to undercoating. Not only will we help you choose the best car undercoating paints for all your needs, but we will also tell you everything you need to know about the hows and whys of undercoating your car.

Factors to Consider in Car Undercoating Paints

With the vast choices available for undercoating your vehicle, you may get confused about what makes them all different from each other.

In order to choose the right undercoating paint for your needs, there are several factors that you need to consider first, such as type, function, filling power, durability, volume, and shelf life.

Type

Although all undercoating paints are designed to protect your car from physical damage and natural elements, different types address different needs. It’s important to know what type of paint you need exactly before making your purchase.

One, there are different types of materials that undercoating paints can be based on, such as petroleum, asphalt, silicone, rubber, ceramics, and fiberglass. Two, undercoating paints differ by application as well. Some need to be manually painted; others come in pressurized spray cans for convenient application.

Simply put, different types have different features and benefits. If you want to learn more, this will be discussed in further detail below.

Function

The most basic function of your undercoating paint is to prevent corrosion and rust on the surface of your vehicle. Other functions that you might want to consider are applicability, sound deadening capabilities, the drying period after application, and aesthetics relative to the design you are going for.

Filling Power

This factor refers to how well your undercoat paint covers and spreads through the tiniest nooks and crannies that are present in the underbelly’s surface so that it can smooth out its surface. This is because the more even the surface of your vehicle’s undercarriage is, the better base it provides in case you may want to paint a topcoat of decorative covering.

Durability

The best undercoating paints can last for up to several years, while others can only last for several months. Keep an eye out for the durability of your coating since this will dictate the reapplication times of your paint as well as the money you may spend for initial and continuing costs.

Volume

Undercoating paint products come in various volume denominations. Some come 16 ounces per can, while others yet contain 5 gallons of material. If you’re DYI-ing your undercoating job, you should factor in how much paint you need for the initial coating, as well as the amount you need to buy for future maintenance. Obviously, bigger vehicles have a bigger surface that needs to be coated, so keep this in mind, too.

Shelf Life

Undercoating paints also come with different shelf lives, which comes hand-in-hand with volume. Most products have a shelf life of at least 1 year after being opened, but sometimes they can be shorter or longer. Let’s say you’re using undercoating paint that only has a shelf life of 6 months. How many times are you planning to reapply undercoating in 6 months? If the answer is “0,” you should buy only what you need for one paint job.

With the wide variety of car undercoating paints present in the market, you may find it difficult to find the best option for you.

Fortunately, that’s what we’re here for. We’ve screened through the most common undercoating products in the market right now and determined the good, the bad, and the ugly. Take a look at the list below to choose the best undercoating paint for your specific needs.

Top 10 Best Car Undercoating Paints 2021

1. Best Overall Undercoating Paint: 3M Professional Grade Rubberized Undercoating

3M Professional Grade Rubberized Undercoating

Why we like it: The smooth, top coat-ready, protective finish of the 3M Professional Grade Rubberized Undercoating certainly lives up to the 3M quality brand name.

Editor’s Rating:

Quick Facts

  • Type: Rubberized, Asphalt-Based
  • Method of Application: Spray
  • Drying Time: 1 hour
  • Shelf Life: N/A

3M is one of the leading brands of automotive chemical manufacturers, which is why it’s no surprise that the 3M Professional Grade Rubberized Undercoating delivers so well. Although it primarily serves to protect the undercarriage of your car from abrasion, rust, and corrosion, it’s actually a multipurpose coat, which means it also works perfectly in quarter panels, under the hood, and on fender interiors, trunk lids, and wheel wells.

It has an asphalt-based formula that dries to a completely smooth rubberized finish. This not only inhibits rust and corrosion but is also the perfect base for a long-lasting topcoat. It also provides good sound deadening, able to reduce both road and engine noise.

It comes in an easy spray can, perfect for touching up small or narrow parts of your vehicle, but not so much when applying over a wide area. Its no-run formula ensures that the application is never messy. However, it doesn’t offer a lot of coverage for its volume, so you’ll have to apply multiple coats just to get proper coverage. For more intense coverage, consider Dupli-Color’s Professional Rubberized Undercoat.

Pros

  • Multipurpose use
  • Strong, asphalt-based formula
  • Easy, no-mess application
  • Sound deadening properties
  • Good for small or narrow parts

Cons

  • More pricey than the competition
  • Difficult to apply on wider areas
  • Needs multiple coats for proper coverage

2. Best Premium Undercoating Paint: POR-15 Rust Preventive Paint

POR-15 Rust Preventive Paint

Why we like it: The POR-15 Rust Preventive Coating isn't just great for undercoating–it's also an amazing choice for all-around protective coating, making it a premium product worth the premium price.

Editor’s Rating:

Quick Facts:

  • Type: Oil-Based
  • Method of Application: Brush or Spray
  • Drying Time: 4.5 hours on average
  • Shelf Life: 2 years if unopened, around 6 months if opened

POR-15’s best-selling Rust Preventive Coating is a high-tech coating that functions splendidly in protecting your car’s underbelly from the elements and preventing rust from forming.

The best thing about this product is that there’s no need to remove rust completely before applying this to your car. It is specifically designed to be applied to any metal surface, as long as it is prepped properly beforehand. The material dries into a non-porous finish that is as hard as a rock and will never crack or peel. It also lasts a long time, provided that you apply it properly.

That said, even premium products have their own downsides. For this one, shelf life is a little subpar at 6 months. It’s also UV-sensitive, so it can’t be directly exposed to sunlight. For a UV-resistant undercoating paint, take a look at Rust Bullet Automotive. If you’re planning to apply POR-15’s paint to areas that will be facing the sun for a while, you should always apply a topcoat. This is not necessary when applied to unexposed areas, though, making it the ideal undercarriage coating for your vehicle.

Pro-Tip

It works best when used with POR 15’s 3-step rust preventive system, which consists of a cleaner/degreaser, a metal prep, and this rust preventive coating. If applying to exposed areas, finish it off with the POR-15 Top Coat.

Pros

  • High-quality performance
  • Protects any kind of metal surface
  • Can be bought in several container sizes
  • Lasts a long time if properly applied

Cons

  • Has a short shelf life after opening
  • Messy application as it stains everything
  • UV-sensitive so not ideal for surfaces exposed to the sun

3. Best Budget Undercoating Paint: Rust-Oleum Professional Grade Rubberized Undercoating Spray

Rust-Oleum Professional Grade Rubberized Undercoating Spray

Why we like it: The Rust-Oleum Professional Grade Rubberized Undercoating Spray is a fantastic option for people who want to protect their car's underbelly completely, especially those on a tight budget.

Editor’s Rating:

Quick Facts

  • Type: Rubberized
  • Method of Application: Spray
  • Drying Time: Dry to the touch in 1 hour; can drive in 24 hours
  • Shelf Life: 5 years if unopened

Rust-Oleum’s Pro-Grade Rubberized Undercoating Spray is called Pro-Grade for a reason. It dries into a protective high-quality rubberized material that prevents rust and protects against salt, chemicals, moisture, and environmental exposure. Since it’s rubberized, it can even save your car from minor road damages like chips or dents. It also has sound deadening qualities that make for a smooth, quiet ride.

Despite its name, this product comes in both spray and paint form. The spray version comes with the brand’s special any-angle technology and a custom spray tip that makes application easy and convenient, even for complete beginners. The material also dries exceptionally fast compared to other rubberized sprays, becoming dry to touch after just one hour. Keep in mind though you should still wait for 24-48 hours before using your car.

That said, this undercoating spray lets out heavy fumes, so make sure you have your protective gear ready. Also, the standard 15 oz can only cover 10-15 sq. ft., which may be too small depending on the size of your vehicle.

Pro-Tip

If your undercarriage is rusty, you should either grind the rust down first or use the Rust-Oleum Rust Reformer Spray before using this undercoating spray.

Pros

  • Budget-friendly
  • High quality, professional-grade product
  • Ease of use with all-angle spray technology
  • Fast drying for a rubberized spray

Cons

  • Spray can only covers 10-15 sq. ft.
  • Releases heavy fumes upon us

4. Easiest-to-Use Undercoating Paint: Dynatron Dyna-Pro Rubberized Undercoating

Dynatron Dyna-Pro Rubberized Undercoating

Why we like it: Dynatron’s Dyna-Pro Rubberized Undercoating is an easy-to-use, instant protection against the harsh elements of your day-to-day commute.

Editor’s Rating:

Quick Facts

  • Type: Rubberized
  • Method of Application: Brush, Roll, or Spray
  • Drying Time: 24 hours
  • Shelf Life: 1 year if unopened, 4 months if opened

Backed by 3M, Dynatron’s Dyna-Pro Paintable Rubberized Undercoating is a very versatile undercoat that can be used on all types of vehicles. It was specifically formulated to protect your vehicle’s undercarriage from chemical corrosion, rust, and chipping.

It has a good coverage and can be easily applied using a brush, roller, or spray. Once it hardens to its thick, rubberized finish, it becomes tough enough to secure your car against the multitude of minor scrapes that it encounters every day. It also has sound-reducing properties to prevent unnecessarily noisy rides.

You can buy the product in 1-gallon cans that are compatible with paint refinish systems, which means it can be easily matched with any desired OEM colors. Unfortunately, this can also be a big downside, since the shelf-life of the Dyna-Pro is quite short compared to competitors.

Pros

  • Fast-drying
  • Strong protection against everyday wear and tear
  • Sound deadening properties
  • Compatible with other paint systems

Cons

  • Pricier than the competition
  • Short shelf-life

5. Most Versatile Undercoating Paint: Rust Bullet Automotive

Rust Bullet Automotive

Why we like it: Tough, versatile, and low-maintenance, Rust Bullet’s Automotive rust inhibitor paint is ideal for undercoating your vehicle and any outdoor metal product that can benefit from its super-strong protection.

Editor’s Rating:

Quick Facts

  • Type: Non-Rubberized Polyurethane
  • Method of Application: Brush, Roll, or Spray
  • Drying Time: 24 hours
  • Shelf Life: 2 years if unopened, 1 month if opened

Rust Bullet’s Automotive rust inhibitor paint not only fights against rust and corrosion but also keeps your undercarriage safe from abrasions and minor damages. You also don’t need to use a primer or topcoat to use this coating. You can apply it directly on rusty or previously painted surfaces, but it’s always best to clean metal surfaces thoroughly first to ensure optimum performance.

It can be applied to a wide variety of areas including undercarriages, floor pans, frames, suspensions, and rocker panels. It can even be applied to areas exposed to the sun, since it’s completely UV-resistant. It’s a little thinner compared to other paints but that only means that it’s much easier to apply and spread. That said, you’ll need a minimum of two coats for it to last a long time.

Do keep in mind that due to its polyurethane formula, this rust inhibitor paint will start hardening almost immediately after you open the product. This means you should only buy the amount that you actually need for one use. It also tends to stick to everything, so be careful when applying it to your car.

It also does not offer any noise deadening benefits. If you’re looking to reduce noise, consider Dupli-Color’s Professional Rubberized Undercoat instead.

Pro-Tip

For best results, apply Rust Bullet Rust Treatment first to rusty areas of your vehicle before using this paint.

Pros

  • Convenient one-step process
  • Completely UV-resistant
  • Protects from physical and chemical damages
  • No heavy metals to damage your vehicle surface

Cons

  • Very short shelf life once opened
  • Sticks to everything and therefore may get messy
  • No noise deadening capabilities

6. Best Undercoating Paint for Aesthetics: Dupli-Color Professional Rubberized Undercoat

Dupli-Color Professional Rubberized Undercoat

Why we like it: Plain, simple, and effective, Dupli-Color’s Professional Rubberized Undercoat is a good choice for anyone looking for an easy-to-use undercoating.

Editor’s Rating:

Quick Facts

  • Type: rubberized
  • Method of Application: spray
  • Drying Time: 2 hours
  • Shelf Life: N/A

Dupli-Color’s Professional Rubberized Undercoat is a quick-dry, paintable-finish formula that aims not only to protect your car’s undercarriage, but also to improve its aesthetics. It dries to a rubberized matte finish that is perfect for top coating and can help the paint retain its color even after a long time.

It provides good protection against rust, corrosion, and minor abrasions from daily use. It also has great noise deadening capabilities because of the rubberized finish. Coverage is good, provided that you prep the surface properly before application.

Although the formula is rather thick, application is quite messy. The nozzle on the spray can is also not very durable and easily breaks. Lastly, it’s not UV-resistant, so you should only use this strictly for your undercarriage or areas that are unexposed to the sun.

Pros

  • Paintable
  • Rubberized, matte, textured finish
  • Noise deadening capabilities
  • Quick-drying
  • Relatively cheap

Cons

  • Not UV-resistant
  • Messy application
  • Flimsy nozzle

7. Best Undercoating Paint for High-Contact Areas: 3M Non-Rubberized Undercoating

3M Non-Rubberized Undercoating

Why we like it: Although it does not perform as great as the brand’s rubberized version, 3M’s multipurpose Non-Rubberized Undercoating is a great, long-lasting, and reliable product in its own right.

Editor’s Rating:

Quick Facts

  • Type: Asphalt-Based
  • Method of Application: Spray
  • Drying Time: 30 minutes
  • Shelf Life: N/A

This version of 3M’s undercoating paint dries solid and very hard. It’s perfect for those areas in your undercarriage that can potentially be exposed to more physical contact with the environment than normal, such as the fenders and wheel wells. Its primary use is to protect the metal from rust, build-up, and abrasions, but it’s also fairly decent at reducing road and vehicle noise.

That said, the substance does take a while to dry. It can take anywhere from 30 minutes to a full 24 hours for it to fully cure. It also requires you to thoroughly prepare your undercarriage before application, or else it could peel off prematurely.

Pros

  • Dries into a hard, protective coating
  • Comes in either paintable or non-paintable variety
  • Covers marks on metal surface
  • Decent sound deadening properties
  • Easy spray application

Cons

  • Takes a long time to dry
  • Required prior preparation

8. Simplest Undercoating Paint: Rusfre Automotive Rubberized Material

Rusfre Automotive Rubberized Material

Why we like it: Rustfre Automotive Rubberized Material’s beauty lies in its simplicity – it doesn’t offer anything revolutionary, but its protective properties are certainly worth your dime.

Editor’s Rating:

Quick Facts

  • Type: Rubberized
  • Method of Application: Brush or Spray
  • Drying Time: N/A
  • Shelf Life: N/A

Rusfre’s Automotive Rubberized Material is an automotive undercoating, pure and simple. Although it does not offer anything new aside from the standard abrasion protection, rust and corrosion inhibition, peel, crack, and chip resistance, and noise reduction, it does deliver on all its promises.

The formula comes out as a viscous substance that semi-hardens into a protective layer. It can be applied using a roller, a paintbrush, or a spray. Although it sticks very well, application can be a bit messy. Not to mention, due to its thickness, it takes a while to dry.

Also, using this product is not a one-step process. Your undercarriage needs to be fully prepped before using this product, which means thorough cleaning and rust removal are required.

Pro-Tip

If you need to apply it to small nooks and crannies where thick liquid can’t go, you only have to dilute the product with an appropriate solvent like an enamel reducer or even mineral spirits.

Pros

  • Very strong, tough bond
  • Different application methods available
  • Reduces vehicle noise
  • Relatively cheap

Cons

  • Application can be messy
  • Takes some time to fully cure and dry

9. Best Restorative Undercoating Paint: Fluid Film Rust & Corrosion Protection

Fluid Film Rust & Corrosion Protection

Why we like it: Fluid Film Rust & Corrosion Protection is a multipurpose coating that can not only be used for your car’s undercarriage, but also to any metal surface that needs protecting from rust and corrosion.

Editor’s Rating:

Quick Facts

  • Type: Petroleum-Based
  • Method of Application: Brush or Roll
  • Drying Time: N/A
  • Shelf Life: N/A

Fluid Film has made a name for itself in the aircraft and aerospace industry as a maker of top-of-the-line lubricant and rust inhibitor products. Now, the brand’s bringing it over into the automotive market with this Rust & Corrosion Protection.

This product provides great value for money in terms of preventative coating for your vehicle’s undercarriage. It provides trustworthy protection against moisture and chemicals, and its thixotropic fluid formula makes sure it gets into the littlest corners of your undercarriage. Not only does it protect the metal from corrosion, but it can also salvage surface-level damage by digging into the metal itself and lifting out the rust over time.

However, do keep in mind that this undercoating doesn’t harden and will not protect against debris or abrasion. It is very gooey and may make a mess. It also has strong fumes that may take some getting used to. You may notice some white smoke during your first few drives after applying this, but rest assured that it’s not flammable enough to catch fire. The white smoke is merely caused by the fluid evaporating when it gets to the exhaust pipe.

Pros

  • Versatile use
  • Digs into the smallest spaces of the vehicle
  • Reliable rust and corrosion prevention
  • Salvages reasonably rust damaged metal

Cons

  • Doesn’t dry completely
  • Very strong fumes
  • No sound deadening
  • May produce white smoke at first

10. Most Stylish Yet Simple Undercoating Paint: Penray Rubberized Undercoat

Penray Rubberized Undercoat

Why we like it: If you’re looking for something simple and a bit fancy at the same time, Penray’s Rubberized Undercoat is a great choice.

Editor’s Rating:

Quick Facts

  • Type: Rubberized
  • Method of Application: Spray
  • Drying Time: 2 hours
  • Shelf Life: 5 years if unopened

Penray may not be as prominent as the other brands on this list, but that doesn’t mean that it doesn’t deserve a spot.

This rubberized undercoating will keep your undercarriage pristine over long periods, protecting it from rust, corrosion, moisture, dirt, and chemicals. It also has great sound deadening properties.

When it comes to aesthetics, it dries to a matte black finish that looks both buffed and classy. It doesn’t need a primer or a topcoat to do its job, but it’s completely paintable with no bleed through in case you want a splash of color. A spray extender comes with the product so you can easily reach narrow areas.

However, make sure to cover up your nose when using this product as it smells quite bad. You should also clean the undercarriage thoroughly before applying this, because while it’s typically adherent to surface material, it does have a hard time bonding to greasy surfaces. Lastly, although Penray markets it as a quick-drying formula, it still doesn’t dry as quickly as we would like.

Pros

  • Convenient application
  • Sound deadening properties
  • Dries to a matte finish and can be painted over
  • Doesn’t need much preparation

Cons

  • Requires multiple coatings for proper coverage
  • Hard to apply to greasy surfaces

The Ultimate Guide to Car Undercoating Paints

car on hydraulic lift

Undercoating your car is a complex job to undertake. You have to consider a lot of factors in order to protect your vehicle in the most efficient way possible. This section of our guide will provide an exhaustive source of all the important information you need to use and apply undercoating paints.

What Are Undercoating Paints?

Undercoating paints provide the most vulnerable part of your vehicle an added layer of protection against harmful elements that you may encounter every day, such as rocks, debris, salt, water, and other minerals that could negatively affect your car.

This kind of paint is typically applied to the car’s exterior, especially the undercarriage. It can also be applied to floorboards, suspension parts, frame, gas tank, pans, and wheel wells of your vehicle. If you’re buying a second-hand vehicle, you should always apply undercoating paint to prevent additional damage to its already fragile underbelly.

How Long Do Car Undercoating Paints Last?

How long your undercoating lasts depends on many factors, like what type of undercoating you used, how well you applied it, how you use your car, and even where you live. Generally, though, car undercoating lasts at least a full year.

If you often use your car on rough terrain or if you live near the ocean, where the chance of rust, corrosion, and chemical damage is greater, there’s a good chance you’ll have to apply undercoating at least once every six months.

Different Types of Undercoating Paints

There are several types of undercoating available in the market, such as water, petroleum, rubber, asphalt, and polyurethane-based paints. Each type has its own strengths and weaknesses that you should consider before picking out which paint is best for you.

Here’s an explanation of each one in a nutshell.

Water-Based

Water-based undercoating paints are the most commonly used paints for DIY undercoating projects. Like other water-based products, they have a thin consistency and dry faster than other types of undercoating paint. They’re also generally sold in aerosol cans for easy application.

The biggest disadvantage of water-based paints is that they wear out faster than other types. This means you’ll need to redo the coating more often for maximum protection, which could be a problem for those who don’t like high-maintenance vehicles.

Wax or Paraffin-Based

Wax or paraffin-based undercoating paints are some of the cheapest options around. They never actually harden and instead seep into the nooks and crannies of your vehicle to protect it from most elements. They are also stronger than water-based paints and can withstand more abuse and exposure.

This type of paint can be either painted on or sprayed, making application quick and easy. However, they still wear off pretty fast, which means you still need to redo the coating at least once a year.

Oil or Petroleum-Based​​​​​

Petroleum-based undercoating is a step above both water and paraffin-based options, as it offers much wider and stronger protection. It can repel road salts, oils, and debris much better than most other types of undercoating paints. Also, petroleum-based compounds are known to be effective at preventing corrosion in vehicles.

However, they’re harder to find in the market, and some petroleum-based undercoating like the Fluid Film Rust & Corrosion Protection never really dries fully – something not everyone likes.

Rubberized

Rubberized formulas are the second-strongest undercoats available on the market. This type of substance is designed specifically for rugged terrains and can withstand stronger exposure and abuse than any other formulas mentioned. They also offer additional features like sound deadening and resistance to dents.

These formulas are very easy to apply and can be painted on or applied as an aerosol spray. They can even be painted over in case you make a mistake and can be removed easily with any undercoating paint remover.

Polyurethane

Polyurethane is one of the most expensive undercoating options out there. It is self-sealing, which means it will seep into the smallest corners and cracks, sealing the surface where it’s applied and pushing out all the salt, sand, dirt, and moisture in the process. Due to this, it’s a great option if you want complete protection for not only your car’s underbelly but also its exterior in general.

This type of undercoating can be purchased in pails or canisters for coating guns. Keep in mind that you have to spend extra time prepping your car’s surface before you apply polyurethane. This includes doing tasks such as degreasing, sanding, and applying an etching primer to metal parts.

Asphalt-Based

Asphalt-based undercoating is designed for military all-terrain vehicles that often see rugged use. It contains some rubber material in it that can help in sound deadening as well.

Compared to other types of undercoating, asphalt-based undercoating is the strongest and the most long-lasting. It does have three downsides worth considering, however. First of all, it’s the most expensive undercoating option in the market right now. It’s also not paintable, which means it can only be used for your car’s underbelly. Lastly, asphalt-based undercoating takes the longest time to fully cure.

Benefits of Undercoating

Not everyone takes the time and effort to undercoat their car. Not that it’s a surprise, considering how many people see undercoating as an expensive waste of time. However, the benefits that come with undercoating can’t be denied.

Here are some of the most significant benefits of undercoating your car.

Provides Additional Protection

Daily wear and tear, when left unattended, can eventually result in irreparable damage to your car. Every time you take out your car for a spin, it accumulates dust, grime, and salt. It also gets exposed to moisture, chemicals, and oxidation. This can lead to rust and mold, two of your car’s biggest enemies.

A good undercoating can prevent all that from happening. It can even protect your car from physical damages like chinks, dents, or scratches. And since all the important parts are covered and water-proofed by the coat, undercarriage cleaning becomes much easier and less risky.

Saves You Money in the Long Run

Anyone who has ever owned a car before will know that repairs are expensive – sometimes, unbelievably so. For instance, it’s not unusual to see repairs for structural damage amount to more than the value of your car.

Remember, the undercarriage is the part that is always exposed to rough terrains, harmful chemicals, and other debris present in the road and the environment. By providing a solid layer of protection to a vulnerable part of your vehicle, undercoating can save you money in the long run. You wouldn’t have to spend so much on repairs if there’s nothing to repair in the first place, right?

May Help Offset Insurance Costs

Insurance providers base their quote on how high-risk your car is. For example, second-hand cars cost a lot of money to insure because they’re more likely to need repairs. Reducing your risks by providing your vehicle more protection may qualify as a discount towards your premiums, especially in states that see high cases of corrosion in vehicles.

Makes Your Vehicle Run Quieter

Undercoating typically contains rubber, allowing the formula to seal the entire underbelly of your car completely. The rubber layer not only protects the surface of your undercarriage from damage but absorbs road noise, as well. The added noise suppression in your vehicle’s interior results in a quieter vehicle and a significantly better driving experience.

Undercoating vs. Rust Proofing

Although people often use the two terms interchangeably, rust proofing and undercoating are technically not the same.

Rust proofing usually refers to applying rust inhabitant on specific spots where rust will most likely form on your vehicle’s body. It usually involves using a thin substance to coat your car and prevent it from developing rust over time.

On the other hand, undercoating is applying a thick, durable, and protective layer of material to the underbelly of your vehicle. It’s meant to cover the floorboard, frame, and the wheel wells – places that are very susceptible to physical and chemical damage in the long run.

Pros and Cons of Undercoating

When you apply undercoating, you’re providing protection to your car’s underbelly against all kinds of damages, rather than just rust. In addition to that, undercoating can also reduce the noise that your car generates on the road, something that plain rust proofing can’t do.

However, undercoating is merely a preventative measure, which means it’s more advisable for newer cars. If your undercarriage has already begun to rust, you’ll have to completely remove all the rust first before you can apply undercoating. Depending on the condition of your vehicle, this can be extremely expensive.

Pros and Cons of Rust Proofing

Rust proofing is meant to lengthen your car’s lifespan as well, and for a typically cheaper price than undercoating. Unlike undercoating, you can still apply rust proofing to areas that have already begun to rust. Rusting is a chemical process, and like all chemical processes, it can always be delayed or stopped – if caught early.

However, rust proofing is becoming less and less popular with the arrival of newer, more rust-resistant materials that cars are made of. Galvanized steel, for example, greatly increases the resistance of car surfaces to rust, making rust proofing a costly redundancy. On the contrary, this doesn’t apply to undercoating, as undercoating protects your car from more than just rust.

Rust Proofing or Undercoating?

If you’re on a tight budget and can only choose one of the two, you should look first at the specific problem you want to solve.

For example, if owning a vehicle for you is all about keeping the exterior spotless and looking good, rust proofing is enough. However, if you’re more concerned about how your car will hold up over ten or so years, then undercoating is a better option.

However, if you have the means to avail both for your car, you don’t have to choose at all. Rust proofing and undercoating are not mutually exclusive – in fact, they complement each other pretty well. Getting both can give your beloved ride the best protection it needs and deserves.

Methods for Applying Undercoating Paints

undercoating paint coming out of sprayer

Different types of undercoating may need different methods of application. Here’s a quick explanation about the two main methods used to apply car undercoating paints.

Brush or Roll

One way to apply undercoating paints is by using a paintbrush or a roller brush. Water-based, wax-based, paraffin-based, and rubberized undercoating typically use this method. It’s very straightforward even for beginners because you can easily control the brush, which means you can paint more than just your car’s undercarriage. The only downside is that it can take up a lot of your time.

Spray

This is the most widely practiced method for applying undercoating to vehicles. Spraying makes sure that the material will adhere properly to your vehicle’s underside to protect it from the elements. However, it can be quite difficult to get an even spread. It’s best to use this method on a new car the day you bring it home.

How To Apply Undercoating Paint

Undercoating your vehicle, although simple in theory, can be an arduous task. To help you out, here’s a step-by-step guide to applying undercoating paint to your car.

Materials

  • Scraper
  • Degreaser
  • Disc grinder and grinding pads
  • Sandpaper
  • Dry rag
  • Primer
  • Undercoating
  • Workshop safety goggles
  • Protective gloves

Steps

  1. Thoroughly clean your vehicle’s undercarriage with a good degreaser. Make sure that no part is left uncleaned.
  2. If there’s any rust present, grind it down with a disc grinder.
  3. Sand down any rust that remains. There should be no rust present before you begin undercoating.
  4. Once that’s done, it’s time to prime the clean undercarriage. If you’re using polyurethane undercoating, etching primer is needed for bare metal parts. Allow the primer to dry completely before proceeding.
  5. Liberally apply undercoating to the undercarriage of your vehicle. Cover all of the exposed parts such as the wheel wells, the frame, the floorboards. Let this first coat dry for at least an hour.
  6. Once the first coat has dried, apply your second coating of undercoat.
  7. Let the undercoating dry for 24 hours at a minimum before you use your vehicle.

If you want to remove undercoating from your car, apply the appropriate paint remover product for the type of undercoat you want to remove. This includes solvents, aircraft strippers, or paint strippers. You can also use a heat gun to soften the undercoating first.

Once the undercoating has already softened, use a scraper to scrape off the undercoating paint, taking care not to damage your vehicle.

What’s the Best Method for Cleaning My Undercarriage?

The best method is to get a professional car wash service to clean your vehicle’s undercarriage thoroughly. However, if you prefer–or don’t mind–doing it yourself, power washers are the best way to get all the dirt and grime off your car. If you don’t have a power washer, a regular garden hose is the next best option.

That said, keep in mind that you’ll have to check more thoroughly if you’re using a garden hose since the pressure may not be strong enough to remove dirt that has already hardened over time.

Also, both power washers and garden hoses aren’t the be all and end all of the undercarriage cleaning. You still have to apply a degreaser and then grind down any instances of rust before applying the undercoat.

Should I Remove My Wheels When Applying Undercoating?

Yes, you should. It may seem like a chore, but you should always remove the wheels of your car before you apply undercoating, especially when using spraying methods. Undercoating is a substance that hardens over time, so if you get it on your wheels, it will form a lump that may throw off your vehicle’s balance while driving.

Once again, always remove all removable parts of your car before undercoating to ensure that the whole process goes smoothly. It’s better to be safe than sorry, after all.

Tips For Undercoating Your Car

Here are some additional tips that you should keep in mind before you undercoat your car.

  • Never apply undercoating to a dirty undercarriage. Once your car has been undercoated, you won’t be able to clean the surface underneath it anymore. Any dirt, mildew, or rust trapped there will slowly corrode your car’s undercarriage.
  • It can be a real pain to clean the mud, dirt, and dust from the underside of your car. To easily rid the undercarriage of road gunk, use a pressurized washer. Once it dries, you can proceed to grinding and sanding down rust, if any. You can also use a rust remover to make sure that no rust remains.
  • Most undercoating products will never stick to greased surfaces, no matter how long you dry it out. Always use a degreaser to completely remove grease from your car’s surface.
  • If you’re using an aerosol spray, do a trial spray first to see the can’s fan pattern. Spray up and down if the paint comes out in a narrow stream, but if it comes out tall and fan-like, spray side to side.
  • Always use safety goggles and a sturdy mask when undercoating. During the process, you’re going to be exposed to a lot of harsh chemical fumes, so it’s best to protect yourself.

Final Words

This list showed you the best undercoating paints that you can get on the market right now. All of them are great options–some more suitable for your situation than others.

Regardless of what you pick though, undercoating is a great way to protect your car from daily wear and tear, prevent rust and corrosion, and prolong its lifespan. Not only does it save you money in the long run, but it also saves your car from otherwise preventable damages.