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What Is the Best Undercoating to Prevent Rust?

If you want to add value, years, and durability to your vehicle, adding an undercoating is the way to go. Rust can wreak havoc, chipping away at the wheel wells, chassis, and underside of your vehicle. Fortunately, you can use an undercoating to prevent rust from ever showing up. There are dozens to choose from, but only a handful are worth buying.

When you’re looking for the best undercoating to prevent rust, you should make sure that it applies easily and lasts for a long time. You can choose from sprays, dips, or paint cans to get the job done. Most undercoatings take between 24 to 48 hours to dry completely before you can drive.

Throughout this article, you’ll also learn the following information about undercoatings:

  • Details about the best undercoatings on the market
  • How you can use undercoating on your vehicle
  • Answers to the most commonly asked questions about undercoating sprays, dips, and paints

Best Undercoatings to Prevent Rust (Reviews)

1. 3M Dynatron Dyna-Pro Paintable Rubberized Undercoating

Rubberized undercoatings offer several years of protection. The 3M Dynatron Dyna-Pro Undercoating is a perfect example of high-quality prevention of corrosion and rust. It comes in a one-gallon can, but you can choose to purchase five gallons to cut back on the price. Either way, you’ll be able to quickly apply each coat in a matter of minutes.

Rubber naturally wicks away moisture, which is one of the primary causes of rust. If you have rust already on the vehicle, scrub it off and apply a layer of this top-notch paintable solution. You’ll notice that the rust stops eating away at the underside of your vehicle, and ceases to come back again.

Pros

  • Enough rubberized liquid per container for a whole vehicle
  • A top-notch formula for several years of protection
  • Perfect for vehicles of all sizes and ages

2. Fluid Film 1-Gallon Can of Rust Inhibitor

The Fluid Film Rust Inhibitor is an eco-friendly solution for people who deal with humidity on a daily basis. Whether your vehicle rusts through harsh winters or high salinity in the air, this liquid film will keep it protected for a long time. It’s much easier to apply than most other solutions because it’s thinner, preventing coagulation and clumps.

Another reason that you might want to consider this undercoating is that it prevents your car from freezing underneath. This corrosion and rust inhibitor won’t allow the metal to freeze, which can ultimately lead to weakened joints and exposed cracks for rust to form.

Pros

  • The easiest solution to paint on your car
  • Prevents rust, corrosion, and frost
  • Perfect for humid, saline environments

3. POR-15 Rust Preventative Coating

Unlike almost every other rust undercoating on the market, the POR-15 Rust Preventative Coating doesn’t require that you remove the rust beforehand. It does the cleanup for you, saving time and money spent on unnecessary materials. Not only that, but it also seals rust permanently, according to the company.

You’ll be able to choose from a variety of colors and sizes if you choose to purchase this undercoating. It comes in clear, silver, gray, gloss black, and semi-gloss black. Matching any and all vehicles, this solution is the best for those who want uniformity. Pick out your color then choose either a pint, quart, or gallon to get the job done.

Pros

  • No need to remove rust prior to applying this product
  • Comes in a wide range of colors and sizes
  • Lasts longer than almost any other rust preventer

4. Rusfre Automotive Spray-On Rubberized Undercoating

The Rusfre Automotive Undercoating is made out of various fibers that prevent rust from building up. It stops chipping and cracking surfaces from inviting moisture and oxygen, which are the two key ingredients of rust and corrosion. Furthermore, it deadens sound to keep those squeaky parts in check.

This product comes in a one-gallon container that’s compatible with the corresponding spray tool. All you have to do is evenly coat the underside of your vehicle with the solid-black liquid. Make sure that you apply the spray when it’s semi-warm outside.

Pros

  • Budget-friendly price for a high-end product
  • Included one gallon of solid-black single-layer liquid
  • Stops corrosion and rust by keeping out moisture

5. Penray Rubberized Undercoat

If you’re looking for a quick solution to your rusty woes, then look no further. The Penray Rubberized Undercoating doesn’t require any preparation at all. You only need to apply a single layer of this top-shelf undercoating spray to prevent rust for many years to come. You’re more than welcome to apply a second coat for additional protection, though.

Aside from preventing rust and corrosion, this undercoat also serves three additional purposes:

  1. It reduces road noise coming in from underneath the vehicle.
  2. You can paint over it with automotive paint without removing the undercoat.
  3. It can be used for gutters, asphalt, and many other applications.

Pros

  • Super easy to apply and dry
  • Can be used for a plethora of helpful purposes
  • Lowers road noise from under your car

6. 3M Professional-Grade Rubberized Undercoating

If you liked the 3M rubberized product from the intro, then the spray-on alternative might be worth looking into. The 3M Professional-Grade Rubberized Undercoating costs significantly less, but you can still use it on motorhomes, cars, trucks, and many other vehicles. It uses a unique no-run formula to prevent drips from staining your driveway, too.

This formula by 3M remains the same as far as longevity and prevention compared to the paintable solution. It’s not a lower or lesser product, despite the fact that it’s significantly less money. The only difference (aside from the application method) is that you’re not getting as much of the rubberized undercoating in a single can as you would with a whole gallon.

Pros

  • Well-trusted, high-quality rubberized undercoating
  • Prevents corrosion and rust from all sources
  • It’s easy to apply this no-drip, no-run formula

7. 3M Undercoating (Non-Rubberized)

There’s no doubt that rubberized undercoatings work excellently, but they’re not always the best solution for every vehicle. If you want a thin coat of a traditional rust-inhibiting liquid, try the 3M Undercoating (Non-Rubberized) Can. It works the same as the previous entry, and it’s also non-drip and no-run when you spray it on.

Much like a few of the other rust undercoatings on this list, this one also cuts down on road noise. Whether you’re cruising in an old muscle car from the ‘60s or driving a brand-new truck, deadening the road noise from underneath is undeniably useful. It also hides welding marks from various modifications.

Pros

  • Non-rubberized liquid no-run solution
  • A single coating is more than enough for most vehicles
  • Perfect for reducing road noise from the underside

8. TRANSTAR Quick-Dry Rubberized Undercoating

The TRANSTAR Quick-Dry Rubberized Undercoating combines the simplicity of spray-on cans with the longevity of paintable undercoatings. You have to spray it along the underside of your vehicle wherever you want to protect it from rust, then use a brush to spread out the liquid. Although it requires a little bit of extra work, it’s well worth the wait.

Getting up to a decade out of this undercoating is just one of the many benefits of using it. You’ll also be able to enjoy reduced sound from the underside, protection from corrosion, virtually zero salt degradation or cracks from humidity, and so on.

Pros

  • Prevents rust and corrosion for up to a decade
  • Incredibly quick-drying formula
  • Compliant with laws and regulations from every state in the USA

9. Evercoat Low-VOC Premium Rubberized Undercoating

The Evercoat Low-VOC Premium Rubberized Undercoating is designed to be quite versatile. You can use it on bare or painted surfaces, and feel free to paint over it with automotive paint once it’s completely dried. It can be used to protect virtually any metal surface, as long as it’s receptive to additional coats.

The texture of this undercoating mirrors traditional rubberized solutions. It’s semi-chunky, adding a visual appeal while also preventing rust and corrosion. It deadens road noise from entering your vehicle, stops humidity from entering cracks, and overall elongates the lifespan of cars, trucks, and motorhomes.

Pros

  • Can be used over or under a layer of automotive paint
  • Perfect for all environments and weather patterns
  • A long-lasting, textured appearance

10. Rust-Oleum Professional-Grade Rubberized Undercoating Spray

Rust-Oleum is another well-known brand in the industry. Their Professional-Grade Rubberized Undercoating Spray not only prevents rust, corrosion, and salt decay, but it also keeps your car protected from projectiles on the road. Whether rocks fly up from the roadside or you’re driving off-road, this tough spray is a good choice for everyone.

Each can cover up to 15 square feet and takes about an hour to dry. As always, you should let it sit for up to 24 hours for a complete cure. Nevertheless, this formula is easy to apply thanks to the ultra-wide spraying nozzle. Attach it to the can and spray from the underside of your vehicle or on individual parts from above.

Pros

  • Easy, quick-drying formula
  • Prevents corrosion, rust, and salt damage
  • Protects your vehicle’s underside from unwanted projectiles

What to Find the Best Undercoating

Before you choose one of the undercoatings to prevent rust from above, you figure out which application will truly be the best for your vehicle. Some of them are better for harsh weather, whereas others prevent vehicular damage.

Here’s a list of what you should look for when you’re buying an undercoating for your vehicle:

  • Do you prefer spraying or painting the solution? They both have their benefits, but it’s worth considering each style of applying the formula. Sprays are usually much easier, but they’re not as neat as paint can be. On top of that, paintable undercoats usually last a bit longer than sprays.
  • Will you be removing rust prior to applying the liquid? Some of the solutions offer protection against rust, but you have to scrub any corrosion or rust from the surface before you use them. However, there are a couple of choices above that allow you to skip the scrubbing.
  • Do you want a rubber or non-rubber undercoat? Rubberized liquids offer the texture and durability that many automotive enthusiasts search for, but it’s not always the best choice. If you drive a high-end vehicle, the appearance of rubberized undercoats might be too rugged. In this case, non-rubberized liquids would be better.
  • Does brand matter to you? Whether you prefer to stick with the known companies or you’re used to trying the same brand every time, there are a few that you might consider. Some of them include Rust-Oleum, 3M, and Penray. That being said, all ten of the products in this article are worth using.
  • How much surface area do you need to cover? You might need a single can, or you might even require several gallons. Remember to check each individual product to figure out how far they go. You wouldn’t want to have to stop in the middle of a project to wait for another shipment!

How to Use Undercoating to Prevent Rust

Using an undercoating properly will save you time, money, and stress. Despite the fact that they’re fairly self-explanatory, there are a few unique steps to some of the products listed.

Remember that you should always wear safety goggles, masks, gloves, and protective clothing. Any undercoat on the market can be dangerous to inhale, and they can all cause skin or eye irritation. This job should be done carefully, taking all of the necessary safety precautions as instructed by the company.

Let’s break down every step in a quick guide below.

  1. Start by wiping down the surface that you’ll be applying the solution to. Even if the product says that you don’t need to remove rust beforehand, it’s a good idea to wipe it down to remove dust and debris. It’ll make it much easier for the liquid to grab a hold of the metal surface without dripping.
  2. (Optional) If the product instructs you to remove rust prior to using their undercoat, now is the time to do so. While many of the products above allow you to skip this step, failure to do so could cause rust and corrosion to wreak havoc underneath the coat. You’ll end up having a serious underlying problem without knowing it until it’s too late. So, check this article and find out how to remove surface rust from a car.
  3. If you’re using paint, use a soft-bristle brush to evenly coat on the surface. Make sure you work from one side to the other, ensuring that you don’t accidentally go over the same spot twice. It’s important that you don’t continuously wet the same areas since they’ll start to layer and clump together.
  4. If you’re using a spray-on solution, spray it evenly back and forth. Again, don’t go over the same area twice. Even if the bottle or can says that you can add another layer, you don’t want an unappealing error that’ll stay for several years.

Allow the undercoat to dry before touching, painting, or driving the vehicle. It’s important to allow the full time as listed by the company. Small indents and fingerprints will last as long as the coating does, which can be quite a long time.

For more information about how long an undercoat lasts, along with other common questions and answers, proceed to the next section.

FAQ

If you’re trying to DIY an undercoating job on your own vehicle, you should get to know all of the facts first. Luckily, you’re in the right place to know everything there is about using rubberized and non-rubberized undercoats (including spray-on and painted variants).

Below, you’ll find all of the answers to the most frequently asked questions.

  • How long does an undercoating last? AvalonKing suggests that high-end undercoats can last up to 10 years before they need a touch-up. That’s not too bad considering most DIY projects cost less than $100. Protecting your vehicle’s underside from noise, rust, corrosion, and projectiles for such a low price is practically a steal.
  • Which is better: Paint or spray-on undercoats? Truthfully, neither of them are generally better than the other. However, they both have advantages. If you want a quick solution that lasts about 3 to 10 years (depending on the company and quality), sprays are the way to go. For a seamless, clean appearance, choose painted undercoats.
  • How long does an undercoat take to dry? According to Rust-Oleum, their undercoats typically take about 30 minutes to dry by the touch, and 24 hours to cure completely. Needless to say, always wait for 24 to 48 hours prior to adding another layer or painting with automotive paint.

Conclusion

Getting the best undercoating to prevent rust will add several years to the life of your vehicle. Some of the parts that develop rust are incredibly expensive, causing you to shovel more money than you’d like. For less than the price of a monthly car payment, these one-time applications are more than worth the investment.

Here’s a quick recap of the post:

  • Rubberized undercoats are excellent for preventing rust, damage, and salt corrosion.
  • For a seamless appearance, choose non-rubberized undercoats.
  • Each coat usually lasts between 3 to 10 years.
  • Remember to go back and forth evenly when you’re applying an undercoat.

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