Underbody Coating

      Underbody rust-preventive coating

The underbody coating that is most commonly used on cars in India and supplied by companies such as 3M is a thick, rubberized paint that forms a 2-3 mm thick coating all along the underside of the car when sprayed on. You also get a thinner clear coat underbody coating which is like a lacquer that coats the entire underside of the car. Some even inject rust-preventive coating material into crevices such as the bottom of doors and door sills, to protect them from rust.

Some car manufacturers already offer some underbody coating straight out of the factory which is usually sprayed inside the wheel arches and under the floor board of the car.

Here are some benefits of underbody coating

Rust Prevention
Ideally any additional underbody coating should be applied when the car is brand new and clean. Car manufacturers use thick paints and sealants for the underbody, but adding an underbody coat especially in coastal cities is useful. Salt water tends to corrode cars really badly.

On bad roads, flying stones and pebbles can chip off the original underbody coating and leave the metal exposed. Using an aftermarket underbody coating offer extra protection.

Sound insulation

The thicker underbody coatings used on cars also act as effective sound dampeners. They can reduce road noise and tyre noise and make the cabin seem quieter – due to the sound absorptive nature of rubberized paints.

Easy maintenance

A uniform black underbody coating gives a car a clean look. It also makes the car easier to maintain by just hosing the underside down. You can be confident that slush build up won’t lead to rusting easily. Most underbody coats these days come with a five-year warranty, which is the lifetime of such a coating.

Here are some of the downsides to underbody coating:

High cost

Cost of underbody coating has come down, but is still expensive. This is because underbody coating offered by a car dealer is one way in which they make money off the customer.

Risk of damage during application

Care must be taken while applying underbody coating. This thick rubberized paint if not applied properly, can get into moving mechanical parts and cause premature failure – such as into the U-joint or CV joints in a cars propeller shaft or drive shafts. They can also hinder smooth movement of suspension components, if applied incorrectly. And there’s also the risk of overspray on to the car’s paint finish on the lower edges of the car.

Teflon coating

Teflon coating is the generic name given for a clear-coat paint sealant that’s applied to the painted surfaces of the car. It is a brand originally owned by Dupont, but now has become generic to the category of PTFE paint sealants. This protects the car’s painted finish and offers a brilliant shine, keeping the vehicle like new for a long time.

Here are the benefits of Teflon coating:

Minor scratch protection

Teflon is a thick clear coat surface that is very slippery. It protects the cars surface from swirl marks and scratches caused by dust and cleaning with a dirty cloth.

Enhances gloss

Putting a clear coat hard wax or Teflon coating on a car evens out the unevenness in the painted surface by filling up minor pits and cracks. This enhances the reflective capability of the paint, giving the car a high-gloss finish that looks like a mirror.

Here are the downsides of Teflon coating:

Not long-lasting

Teflon coating does not last long enough. The effect can wear off in about six month’s time after which it will need to be redone or you have to switch to a hard-wax polish for the car. The benefits of a hard-wax too are not long-lasting, but can be re-done at a much lower cost.

High cost

The high-cost of Teflon-coating application is another down side. Car dealers often charge high amounts in excess of Rs. 3,000 to coat a car, where most of the cost goes towards the dealer’s profit margin. If you have the time and patience, a good hard wax is a better option for your car.

Tell us if you know of any other pros and cons to underbody coatings and Teflon coatings, so that other CarToq community members can make an informed decision of such services dealers and car accessory shops.

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Benefits of Undercoating

• Save money. It’s expensive to have your car undercoated by a professional since it can cost hundreds of dollars for one session. Moreover, you would also have to wait for a couple of days before the job is done. Instead of spending a fortune on an undercoating service, buy a quick-dry undercoat and do the job yourself.
• Reduce road noise. A vehicle’s undercarriage gets noisier as time goes by due to rust and wear. Most undercoats are formulated to seal all the nooks and crannies on the undercarriage that typically lead to road noise. 
• Add an extra layer of protection. An undercoat typically acts as an additional layer of protection from mold, moisture, dust, and rot. It also protects your vehicle from dents, scratches, and paint chips.
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Types of Vehicle Undercoating

Rubberized Undercoating

Rubberized undercoating is easy to apply, and generally offers the best protective coating for your car’s undercarriage. It cushions surfaces against moisture, rust, dings, and dents. Rubberized undercoating is safe to use on quarter panels and wheel wells and dries with a soft rubbery finish.

Asphalt-Based Undercoating

Asphalt-based undercoating offers a higher level of protection suitable for large trucks, recreational vehicles, and heavy machinery. It’s formulated with some bits of rubberized material to aid in noise reduction. It offers extra protection against chips and moisture but is not paintable and, therefore, only suitable for undercarriages.

Polyurethane Undercoating

Polyurethane coating is easy to apply and works by sealing up cracks and seams. The compound displaces salt and moisture and protects the unoxidized metal from rust. It’s often sold in canisters that are ready to preload into an application gun. It, however, requires some surface prep work before application, like degreasing, and applying an etching primer to the bare metal.

Wax or Paraffin-Based Undercoating

Wax or paraffin-based undercoating sprays are the cheapest and quickest options available. However, their results don’t last long, and you may have to apply a fresh coat after only a few months. In addition, the wax isn’t very adhesive on a metal surface. Its main advantage is that it seeps quickly into cracks and seams, and offers moderate protective properties against moisture. 

 Key Features

Volume

Vehicle undercoating products come in volumes from 16 ounces to about 5 gallons. Think of how much undercoat you will use in the current job, the size of your vehicle, and how much you will need to buy in the near future. A 16-ounce bottle is suitable for a small car, but an RV or a truck will need a 1-gallon jug to get the job done.

Shelf Life

Most premium undercoating materials have a shelf life of at least one year after being opened. Others can only last for a few months, then they start to wear off. If you find a fully functional product with a short shelf life, it’s prudent to buy it in small portions. Figuring that you will use the undercoat at least once a year, the shelf life shouldn’t be an issue if you go for the right portions.

Formulation

The formulation you choose depends on your budget and how long you want the coat to last. Rubberized and asphalt-based undercoats are more expensive, but a single coating job can last up to a year or longer depending on the environmental conditions. Cheaper options like paraffin-based formulations last for only a few months, and you may not be able to stand the smell.

Other Considerations

• Functionality: The undercoating spray should be able to at least prevent rust and corrosion on the metal surface. It should also be paintable, have sound deadening properties, have quick drying time, and improve the aesthetics of the sprayed surface.
• Filling Power: The filling power is a measure of the undercoat’s ability to seep through cracks and holes, to smoothen out irregular surfaces. An even surface sets a great base for the topcoat paint and makes the vehicle's body look more appealing.